Exploring the Influence of DNA Methylation and family factors on OCD and symptoms Severity: Insights into the TPH2 Gene

Exploring the Influence of DNA Methylation and family factors on OCD and symptoms Severity: Insights into the TPH2 Gene | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Exploring the Influence of DNA Methylation and family factors on OCD and symptoms Severity: Insights into the TPH2 Gene Lina Wang, Yu Chen, Shiqi Hu, Tiangui Yu, Zhenhua Liu, Dongdong Qiao This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4247451/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 30 Sep, 2025 Read the published version in BMC Psychiatry → Version 1 posted 10 You are reading this latest preprint version Abstract Objective: The etiology of obsessive-compulsive disorder (OCD) remains incompletely understood. Previous studies have implicated the TPH2 gene and several family factors in OCD. This study aimed to investigate the correlation of TPH2 gene methylation and family factors (parenting styles and family functioning) on OCD and its clinical severity. Method: A total of 88 patients with OCD and 94 healthy controls were enrolled. DNA methylation levels at twelve sites in the promoter region of the TPH2 gene were measured using DNA inflight mass spectrometry system and polymerase chain reaction (PCR). The severity of OCD symptoms was assessed using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). Egna Minnen Barndoms Uppfostran (EMBU) and Family Assessment Device (FAD) scales were used to measure parenting styles and family functioning, respectively. Results: DNA methylation levels of CpG site 5 were negatively correlated, and site 6 was positively associated with the onset of OCD. Further analysis revealed a positive association between DNA methylation level at CpG site 5 and a paternal-favoring parenting style as measured by the EMBU in OCD. Additionally, DNA methylation levels at CpG site 2 were positively correlated with maternal emotional warmth of EMBU but negatively correlated with the general functioning of FAD; they were also negatively correlated with compulsive behavior scores and total scores of Y-BOCS. DNA methylation levels at CpG site 1,3,8 were negatively associated with maternal emotional warmth of EMBU while positively correlated with compulsive behavior scores and total scores of Y-BOCS. Moreover, DNA methylation levels of CpG site 9, 10 and 12 were positively associated with problem-solving, total scores of Y-BOCS, and maternal emotional warmth, respectively. Obsessive thoughts were found to be negatively associated only with paternal emotional warmth of EMBU. Conclusion: DNA methylation at different CpG sites in the promoter region of the TPH2 gene may play critical roles in the onset and progression of OCD. Parenting styles and family functioning could impact the progression of the disease, and the DNA methylation of the TPH2 gene may mediated the effect of family factors on OCD. TPH2 gene DNA methylation Family factors Obsessive-compulsive disorder 1. Introduction Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder characterized by obsessive thoughts and compulsive behavior, which seriously damages patients' quality of life and brings severe financial and emotional stress to families and society (Pampaloni I et al., 2022 ; Hirschtritt ME et al.,2017). The disability-adjusted life years (DALYs) of OCD are more than those of sclerosis and Parkinson's disease combined (Goodman WK et al.,2014). To date, OCD has received increasing attention because of the severe damage it can cause to individuals, but its etiology is not yet fully understood. Genetic and environmental factors may have varying degrees of risk for the onset and development of OCD (Toro J et al., 1992 ; Murphy YE et al., 2015). Parenting styles and family functioning have been studied as one or more dimensions of family factors associated with OCD. Parents of OCD patients showed similar features in parenting styles regarding severity, excessive involvement, and lack of warmth (Mathieu SL et al., 2020 ). Aspects of family functioning such as Affective Responsiveness, Communication, and Problem Solving may be involved in the development of OCD as studies have shown that these factors were related to the severity of symptoms (Alonso P et al., 2004 ; Smári J et al., 2010 ; Lennertz L et al., 2010 ; Haciomeroglu B et al., 2014). The view on gene-environment interactions (G×E) suggests that risk factors, whether genetic or environmental, play a probabilistic rather than a deterministic role in disease (Assary E et al., 2018 ). According to a recent systematic review, G×E is associated with susceptibility, clinical characteristics, and treatment response in OCD (Wang L & Chen Y et al., 2023 ). Epigenetic mechanisms are a vital part of the G×E system, and epigenetic modifications are dynamic and can be changed by environmental factors, such that they constitute a molecular basis underlying GxE interactions (Feinberg ME et al., 2007 ; Jirtle et al. MK, 2007; Bollati V & Baccarelli A et al., 2010 ; Zhang L et al., 2020 ). DNA methylation is an essential epigenetic modification in the human genome, which can dynamically control gene expression (Liu C et al., 2018 ). Neuronal activity could modulate the pattern of DNA methylation in response to physiological and environmental stimuli (Martinowich K et al., 2003 ; Guo ZY et al., 2011 ). DNA methylation in different genomic regions may influence gene activities based on the underlying genetic sequence (Moore LD et al., 2013 ). Tryptophan hydroxylase-2 (TPH2) is predominantly expressed in the brain, which is a second, neuron-specific TPH isoform, the rate-limiting enzyme in 5-Hydroxytryptamine (5-HT) biosynthesis (Chen GL & Miller GM et al., 2012). TPH2 was found mainly in the brain stem and was encoded by the TPH2 gene located on human chromosome 12 and mouse chromosome 10 (Walther DJ et al., 2003). On the one hand, TPH2 gene expression is influenced by genetic factors, and studies have shown that a functional polymorphism of the TPH2 gene could affect the synthesis and transmission of 5-HT in the nervous system (Zhang X et al., 2005 ; Jacobsen JP et al., 2012 ; Gutknecht L et al., 2008 ). On the other hand, researchers have proposed that TPH2 gene expression is tissue-specific and responsive to stressors (Gardner KL et al., 2009 ; Mueller BR & Bale TL, 2008). Previous studies suggested that TPH2 regulation of the midbrain saber synapse played an essential role in the pathogenesis of OCD (Mössner R et al., 2006 ) and that TPH2 gene expression was closely associated with epigenetic mechanisms (Chen GL et al., 2012). Thus, epigenetic alterations in the TPH2 gene may play a role in OCD. This study aimed to investigate the role of TPH2 gene DNA methylation in the onset and development of OCD. Meanwhile, the relationship among DNA methylation of the TPH2 gene, family factors (parenting styles and family functioning), and the clinical characteristics of OCD has been explored. 2. Methods 2.1. Participants This study is a cross-sectional study. The case group was recruited from the inpatient department of Shandong Mental Health Centre between September 2019 and January 2022. Patients were included according to the following criteria: 1) meeting the diagnostic criteria for OCD in the 10th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-10); 2) age 10–65 years, male or female; 3) biological parents of Han Chinese ethnicity. Exclusion criteria included: 1) major physical illness related to the circulatory, urinary, hematological, or motor systems; 2) previous or existing organic brain disease or endocrine system disease; 3) concomitant psychoactive substance abuse; 4) pregnant and lactating women; 5) history of diagnosis for any other mental disorders. An age- and gender-matched control group was recruited from the community. All participants voluntarily declared their consent to participate in this study. The Ethics Committee of Shandong Mental Health Center granted ethical approval. 2.2. Assessments A concise, self-made questionnaire was used to record the sociodemographic data of the age and gender of all the participants. In patients, OCD severity was assessed via the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), with items 1–5 reflecting symptoms related to obsessions and items 6–10 related to compulsions (Goodman WK et al.,1989). Parenting attitudes and behaviors were assessed quantitatively using the Egna Minnen Barndoms Uppfostran (EMBU), and factor analysis of the EMBU identified the following four primary dimensions: rejection, emotional warmth, overprotection, and favoring subject (Richter J et al., 1991 ; Benjaminsen S et al., 1984 ). The Family Assessment Device (FAD) was used to assess the functioning of the family system in which the individual lives which was divided into seven subscales, including problem solving, communication, roles, affective responsiveness, affective involvement, behavior control, and general functioning. FAD is a comprehensive assessment of the state of family relationships and the ability to adapt to changing social circumstances (Peris TS et al., 2019 ). 2.3. DNA extraction DNA extraction was done based on peripheral venous blood samples from patients with OCD and controls. The peripheral blood was collected at 7:00 am after fasting for at least eight hours using EDTA anticoagulation tubes and then centrifuged at 3000 rpm for 10 minutes. Immediately after centrifugation, the middle layer of leukocytes was extracted and stored in EP tubes at -80°C in the refrigerator until use. DNA extraction was performed using a medium-volume whole-blood DNA extraction kit provided by BioTeKe Corporation. Primer synthesis provided by Thermo Fisher detected the DNA methylation, and Zymo and Agena provided the Methylated DNA Nitrite Kit and EpiTYPER™ Reagent Kit, respectively. The DNA methylation levels were quantified through the Agena MassArray DNA flight mass spectrometry system and polymerase chain reaction (PCR) by Beijing Liuhe Huada Gene Technology Co. 2.4. Determination of DNA methylation level In this study, the screening of CpG sites in the promoter region of the TPH2 gene was performed by the online prediction website ( http://www.ebi.ac.uk/Tools/seqstats/emboss_cpgplot ). A total of 13 CpG sites were identified, among which CpG site 1, CpG site 3, and CpG site 8 fragments were found to have the same molecular weight and product peaks after enzymatic digested by MassArray system and Polymerase Chain Reaction (PCR), so they were combined as CpG site 1,3,8 (Ellis JA & Ong B, 2017). CpG site 13 was not provided due to problems with the sequence. 2.5. Statistical analysis The statistical data were analyzed by using SPSS 27.0 software. The Shapiro-Wilk test was used to examine the normality of each variable. The Chi-square test was applied to investigate group differences when the dependent variable was measured at a nominal level. The t-test was carried out to compare means between two independent groups. The binary logistic regression analysis model was used to analyze the risk or protective factors that predicted the occurrence of OCD. Spearman's rank correlation was used to explore the correlation. The significance level was set at P < 0.05. 3. Results 3.1 General information of participants A total of 88 patients (52 males and 36 females, mean age ± SD: 24.64 ± 13.73 years) were enrolled in this study. The control group comprised 94 healthy individuals (50 males and 44 females, mean age ± SD: 26.06 ± 9.85 years). There were no statistical differences in age and gender between the two groups ( Table 1 ) . Table 1 Sample sizes and demographics in case and control groups Patients (n = 88) Controls (n = 94) t /χ² P value Age Gender (Male/Female) 24.64 ± 13.73 52/36 26.06 ± 9.85 50/44 0.810 0.642 0.419 0.423 3.2 Comparison of DNA methylation levels in patients and controls The DNA methylation levels at different CpG sites in the promoter region of the TPH2 gene were compared between patients and controls. The results in Table 2 showed that the DNA methylation levels at CpG site 6 were positively associated with OCD (B = 3.261, P = 0.045), while the levels at CpG site 5 were negatively correlated with OCD (B = -11.856, P = 0.001). However, only the difference of CpG site 5 remained significant after Bonferroni correction ( P < 0.005 correcting for 10 tests). In other words, DNA methylation at this site of the TPH2 gene was a “protective” factor for the onset of OCD (the result remained significant, rectified by age and gender). Table 2 Comparison of DNA methylation levels between groups Patients Controls CpG sites Max Min M SD Max Min M SD B SE z value P OR OR(95%CI) CpG_1,3,8 0.36 0.00 0.20 0.09 0.55 0.00 0.21 0.10 -0.259 2.069 0.016 0.900 0.772 0.013 ~ 44.560 CpG_2 0.63 0.00 0.45 0.10 0.64 0.00 0.47 0.10 -1.480 2.135 0.480 0.488 0.228 0.003 ~ 14.959 CpG_4 1.00 0.05 0.74 0.26 1.00 0.20 0.83 0.20 -1.366 0.865 2.496 0.114 0.255 0.047 ~ 1.389 CpG_5 0.21 0.00 0.08 0.06 0.25 0.00 0.11 0.05 -11.856 3.604 10.822 0.001** 0.000 0.000 ~ 0.008 CpG_6 0.47 0.00 0.20 0.13 0.49 0.00 0.15 0.11 3.261 1.627 4.016 0.045* 26.072 1.074 ~ 632.729 CpG_7 0.31 0.00 0.08 0.06 0.35 0.00 0.08 0.07 -0.992 3.077 0.104 0.747 0.371 0.001 ~ 154.379 CpG_9 0.26 0.00 0.06 0.06 0.18 0.00 0.05 0.04 3.982 4.328 0.847 0.357 53.643 0.011 ~ 259047.654 CpG_10 0.37 0.00 0.08 0.06 0.37 0.00 0.08 0.05 -2.175 4.069 0.286 0.593 0.114 0.000 ~ 330.553 CpG_11 0.33 0.00 0.07 0.07 0.89 0.00 0.07 0.11 0.038 1.909 0.000 0.984 1.038 0.025 ~ 43.767 CpG_12 0.92 0.00 0.11 0.14 0.89 0.00 0.12 0.17 -0.683 1.213 0.317 0.573 0.505 0.047 ~ 5.439 Max, maximum; Min, minimum; M, mean; SD, standard deviation. * P < 0.05, ** P < 0.01 3.3 Relationship between epigenetic and environmental factors in OCD patients A total of 41 OCD patients completed the EMBU and FAD scales and their symptom severity was evaluated by the Y-BOCS. The relationship between family factors (EMBU, FAD) and twelve CpG sites of the TPH2 gene was then analyzed using Spearman's rank correlation. Results showed that the DNA methylation levels at CpG site 2 were negatively associated with general functioning of FAD ( r ρ = -0.345, P = 0.027) and positively correlated with maternal emotional warmth of EMBU ( r ρ = 0.352, P = 0.024) in patients. In contrast, the maternal emotional warmth was negatively associated with the DNA methylation levels of CpG site 1,3,8 ( r ρ = -0.338, P = 0.031). The DNA methylation levels at CpG site 5 and site 12 were positively related to the paternal and maternal favoring subject of EMBU ( r ρ = 0.380, P = 0.014; r ρ = 0.327, P = 0.037), respectively. The results also revealed that Problem Solving of FAD was positively associated with the DNA methylation at CpG site 9 ( r ρ = 0.361, P = 0.021). No other association was found between the investigated environmental factors, and patients’ epigenetic alteration. Detailed results are summarized in Table 3 . Table 3 Relationship between Family factors and DNA methylation levels in patients Paternal favoring subject Maternal emotional warmth Maternal favoring subject Problem solving General Functioning Speraman's ρ P Speraman's ρ P Speraman's ρ P Speraman's ρ P Speraman's ρ P CpG_1,3,8 0.174 0.277 -0.338 0.031* 0.027 0.868 0.097 0.548 0.268 0.090 CpG_2 0.018 0.912 0.352 0.024* 0.158 0.324 0.033 0.839 -0.345 0.027* CpG_5 0.380 0.014* -0.145 0.366 0.255 0.108 -0.086 0.594 -0.168 0.293 CpG_9 0.102 0.526 -0.038 0.815 -0.026 0.872 0.361 0.021* 0.228 0.151 CpG_12 0.215 0.177 0.142 0.376 0.327 0.037* -0.066 0.682 -0.073 0.651 * P < 0.05 3.4 Association of epigenetic and environmental factors with OCD symptoms severity Spearman's rank correlation was also applied to analyze the effect of epigenetic, and environmental factors on the severity of OCD symptoms. As Table 4 showed, obsessive thoughts were negatively associated with paternal emotional warmth of EMBU ( r ρ = -0.327, P = 0.037); and the scores of compulsive behaviors and Y-BOCS total scores were negatively related to the DNA methylation levels at CpG site 2 ( r ρ = -0.436, P = 0.004; r ρ = -0.489, P = 0.001) while positively related to the levels at CpG site 1,3,8, (r ρ = 0.331, P = 0.035; r ρ = 0.311, P = 0.048). Meanwhile, Y-BOCS total scores was positively associated with the methylation levels at CpG site 10 ( r ρ = 0.326, P = 0.037). There was no other significant association between the analyzed Y-BOCS scores and the family (EMBU, FAD) factors and epigenetic alteration. Table 4 Association of Family factors and DNA methylation levels with symptoms severity Paternal emotional warmth CpG_1,3,8 CpG_2 CpG_10 Speraman's ρ P Speraman's ρ P Speraman's ρ P Speraman's ρ P Obsessive thoughts -0.327 0.037* 0.051 0.753 -0.088 0.586 -0.036 0.824 Compulsive behaviors -0.129 0.421 0.331 0.035* -0.436 0.004** 0.306 0.051 Y-BOCS total scores -0.253 0.111 0.311 0.048* -0.489 0.001** 0.326 0.037* * P < 0.05, ** P < 0.01 4. Discussion In this study, the association among DNA methylation of the TPH2 gene, family psychological characteristics (parenting style, family functioning), and OCD was investigated. We found that the DNA methylation levels at CpG site 5 and site 6 of the TPH2 gene promoter region was correlated with OCD susceptibility, while only CpG site 5 remained to have the negative association after multiple corrections. DNA methylation levels at different CpG sites (CpG site 1,3,8, CpG site 2, CpG site 5, CpG site 9, CpG site 12) were associated with various factors of family psychological characteristics in patients. In addition, the DNA methylation levels (CpG site 1,3,8, CpG site 2, CpG site 10) and paternal emotional warmth of EMBU were found to be related to the symptoms severity of OCD. This study suggested that the DNA methylation of CpG site 5 may act as a “protective” factor against the onset of OCD. Although not related to symptom severity, it was found to be positively associated with the paternal favoring parenting style in OCD patients. A similar positive correlation was observed between maternal favoring subjects and DNA methylation of CpG site 12. Previous studies have indicated that the onset and severity of OCD, as well as its co-morbidity, were negatively correlated with positive parenting styles (such as emotional warmth and preference) of fathers (Alonso P et al., 2004 ; Mathieu SL et al., 2020 ), which may be consistent with our findings. Considering previous research showing that TPH2 expression was regulated by DNA methylation of the TPH2 gene promoter region in patients with major depressive disorder (MDD) (Zhang Y et al., 2015 ), and based on the hypothetical assumption of a serotonin imbalance (Hirschtritt ME et al., 2017 ), the results of this study suggest a possible neurogenetic mechanism. Specifically, an upbeat paternal parenting style may reduce the risk of developing OCD by promoting DNA methylation of CpG sites in the TPH2 gene. The promoter region of the TPH2 gene contains several scattered CpG sites rather than CpG islands (Chen GL & Miller GM, 2012). Studies have demonstrated that regulatory polymorphisms of TPH2 may differentially influence the response to environmental factors, presumably due to their differential roles in gene expression regulation (Shen T et al., 2020 ; Tan T et al., 2022 ). Similarly, our findings suggested that the onset and development of OCD may be regulated by DNA methylation at different CpG sites of the TPH2 gene. We observed that the DNA methylation level at CpG site 2 was positively correlated with maternal emotional warmth but negatively correlated with the patients' compulsive behaviors and the Y-BOCS total scores. However, the DNA methylation levels of CpG sites 1, 3, 8 exhibited results that were contrary to those of CpG site 2. In addition, paternal emotional warmth was found to be negatively associated with obsessions. A previous study revealed that patients with OCD reported less parental emotional warmth and more control and rejection than healthy individuals (Lennertz L et al., 2010 ). Parental emotional warmth had a negative association with clinical features of OCD (Mathieu SL et al., 2020 ). Thus, we hypothesize that positive parenting styles, such as parental emotional warmth, may be linked with OCD severity through the epigenetic modification of the TPH2 gene in patients. Regarding the association between family functioning and OCD, patients were found to reported significantly poorer family functioning, excluding the Affective Involvement dimension, as assessed by FAD (Wang J & Zhao X, 2012 ). The general functioning dimension of FAD is utilized to assess individuals' overall level of family functioning, with higher scores indicating lower levels of social support (Cong CW et al., 2022 ). Although general functioning did not exhibit a correlation with OCD severity in this study, it was negatively correlated with the DNA methylation level of CpG site 2, which, in turn, was negatively correlated with compulsive scores and the Y-BOCS total score in this study. Therefore, a hypothesis has been posited that general functioning may impact the progression of OCD through involvement in the epigenetic modulation of the TPH2, which requires validation in a larger sample size. Problem solving dimension refers to the family's capacity to address issues while maintaining an adequate level of family functioning, which is relevant to the risk and maintenance of anorexia nervosa (AN) (Monteleone AM et al., 2024 ). A novel finding from our study was that problem solving of FAD was positively associated with the DNA methylation levels of CpG site 9. Since this site did not exhibit a correlation with OCD, further investigation is warranted to determine whether and how this association with problem solving affects OCD. This study is subject to several limitations. Firstly, the sample size was modest, which may have resulted in a relatively low statistical power. Secondly, the quantification of family factors relied on information obtained from scales, which could introduce bias in the recall and reporting of the individuals tested. Thirdly, the patients with OCD included in this study were all hospitalized, so our findings may not be generalized to outpatients or those who do not seek therapy. OCD is a complex disease with pathogenesis potentially influenced by numerous factors. Therefore, further multi-omics studies based on larger sample sizes and investigations into the role of multifactor gene-environment interactions in OCD are warranted. 5. Conclusion In summary, the present study was the first to investigate the relationship between DNA methylation in the TPH2 gene, family factors, and the onset and progression of OCD. It is suggested that DNA methylation at distinct CpG sites could have varying impacts on the occurrence and course of OCD. Family factors may influence OCD through their impact on DNA methylation of the TPH2 gene. Declarations Ethics approval and consent to participate This study was conducted in accordance with the Declaration of Helsinki. And the study was approved by the Ethics Committee of Shandong Mental Health Center (No. 2020R38). An informed consent was signed by each participant before participating in this study. We confirmed that all methods were performed in accordance with the relevant guidelines and regulations. Consent for publications Not applicable. Competing interests The authors have no actual or potential conflicts of interest to declare. Funding This study was funded by Shandong Province Key R&D Program Project (2016GSF201200) and Shandong Province Key R&D Program (Science and Technology Demonstration Project) Project (2021SFGC0504). The funding bodies played no role in the design of the study and collection, analysis, and interpretation of data or in writing the manuscript. Author Contribution Dongdong Qiao and Lina Wang designed the study; Lina Wang and Zhenhua Liu were responsible for the clinical diagnosis; Yu Chen and Shiqi Hu conducted sample collection, performed the experiments and analyzed the data; Lina Wang, Yu Chen and Zhenhua Liu were responsible for manuscript writing; Tiangui Yu and Dongdong Qiao supervised the study. All authors have read and approved the final manuscript. Acknowledgements We thank all the participants for their support in this study. Data Availability Researchers interested in this study may contact corresponding author to obtain relevant data via email: [email protected] . References Alonso P, Menchón JM, Mataix-Cols D, Pifarré J, Urretavizcaya M, Crespo JM, Jiménez S, Vallejo G, Vallejo J. Perceived parental rearing style in obsessive-compulsive disorder: relation to symptom dimensions. Psychiatry Res. 2004;127(3):267–78. Assary E, Vincent JP, Keers R, Pluess M. Gene-environment interaction and psychiatric disorders: Review and future directions. Semin Cell Dev Biol. 2018;77:133–43. Bollati V, Baccarelli A, Sartori S, Tarantini L, Motta V, Rota F, Costa G. Epigenetic effects of shiftwork on blood DNA methylation. Chronobiol Int. 2010;27(5):1093–104. Benjaminsen S, Jørgensen J, Kragh-Hansen L, Pedersen LL. Memories of parental rearing practices and personality features. Acta Psychiatr Scand. 1984;69(5):426–34. Chen GL, Miller GM. Advances in tryptophan hydroxylase-2 gene expression regulation: new insights into serotonin-stress interaction and clinical implications. Am J Med Genet B Neuropsychiatr Genet. 2012;159B(2):152–71. Cong CW, Tan SA, Nainee S, Tan CS. Psychometric Qualities of the McMaster Family Assessment Device-General Functioning Subscale for Malaysian Samples. Int J Environ Res Public Health. 2022;19(4):2440. Ellis JA, Ong B. The MassARRAY® System for Targeted SNP Genotyping. Methods Mol Biol. 2017;1492:77–94. Feinberg ME, Button TM, Neiderhiser JM, Reiss D, Hetherington EM. Parenting and adolescent antisocial behavior and depression: evidence of genotype x parenting environment interaction. Arch Gen Psychiatry. 2007;64(4):457–65. Gardner KL, Hale MW, Oldfield S, Lightman SL, Plotsky PM, Lowry CA. Adverse experience during early life and adulthood interact to elevate tph2 mRNA expression in serotonergic neurons within the dorsal raphe nucleus. Neuroscience. 2009;163(4):991–1001. Goodman WK, Price LH, Rasmussen SA, Mazure C, Fleischmann RL, Hill CL, Heninger GR, Charney DS. The Yale-Brown Obsessive Compulsive Scale. I. Development, use, and reliability. Arch Gen Psychiatry. 1989;46(11):1006–11. Goodman WK, Grice DE, Lapidus KA, Coffey BJ. Obsessive-compulsive disorder. Psychiatr Clin North Am. 2014;37(3):257–67. Guo ZY, Hao XH, Tan FF, Pei X, Shang LM, Jiang XL, Yang F. The elements of human cyclin D1 promoter and regulation involved. Clin Epigenetics. 2011;2(2):63–76. Gutknecht L, Waider J, Kraft S, Kriegebaum C, Holtmann B, Reif A, Schmitt A, Lesch KP. Deficiency of brain 5-HT synthesis but serotonergic neuron formation in Tph2 knockout mice. J Neural Transm (Vienna). 2008;115(8):1127–32. Haciomeroglu B, Karanci AN. Perceived parental rearing behaviours, responsibility attitudes and life events as predictors of obsessive compulsive symptomatology: test of a cognitive model. Behav Cogn Psychother. 2014;42(6):641–52. Hirschtritt ME, Bloch MH, Mathews CA. Obsessive-Compulsive Disorder: Advances in Diagnosis and Treatment. JAMA. 2017;317(13):1358–67. Jacobsen JP, Siesser WB, Sachs BD, Peterson S, Cools MJ, Setola V, Folgering JH, Flik G, Caron MG. Deficient serotonin neurotransmission and depression-like serotonin biomarker alterations in tryptophan hydroxylase 2 (Tph2) loss-of-function mice. Mol Psychiatry. 2012;17(7):694–704. Jirtle RL, Skinner MK. Environmental epigenomics and disease susceptibility. Nat Rev Genet. 2007;8(4):253–62. Lennertz L, Grabe HJ, Ruhrmann S, Rampacher F, Vogeley A, Schulze-Rauschenbach S, Ettelt S, Meyer K, Kraft S, Reck C, Pukrop R, John U, Freyberger HJ, Klosterkötter J, Maier W, Falkai P, Wagner M. Perceived parental rearing in subjects with obsessive-compulsive disorder and their siblings. Acta Psychiatr Scand. 2010;121(4):280–8. Liu C, Jiao C, Wang K, Yuan N. DNA Methylation and Psychiatric Disorders. Prog Mol Biol Transl Sci. 2018;157:175–232. Martinowich K, Hattori D, Wu H, Fouse S, He F, Hu Y, Fan G, Sun YE. DNA methylation-related chromatin remodeling in activity-dependent BDNF gene regulation. Science. 2003;302(5646):890–3. Mathieu SL, Conlon EG, Waters AM, Farrell LJ. Perceived Parental Rearing in Paediatric Obsessive-Compulsive Disorder: Examining the Factor Structure of the EMBU Child and Parent Versions and Associations with OCD Symptoms. Child Psychiatry Hum Dev. 2020;51(6):956–68. Monteleone AM, Marchetto C, Cascino G, Criscuolo M, Carfagno M, Castiglioni MC, Caramadre A, Barone E, Zanna V. The bidirectional connection between family functioning and psychopathology: A network analysis in a large sample of adolescents with anorexia nervosa and their parents. Fam Process. 2024 Mar 13. Mössner R, Walitza S, Geller F, Scherag A, Gutknecht L, Jacob C, Bogusch L, Remschmidt H, Simons M, Herpertz-Dahlmann B, Fleischhaker C, Schulz E, Warnke A, Hinney A, Wewetzer C, Lesch KP. Transmission disequilibrium of polymorphic variants in the tryptophan hydroxylase-2 gene in children and adolescents with obsessive-compulsive disorder. Int J Neuropsychopharmacol. 2006;9(4):437–42. Moore LD, Le T, Fan G. DNA methylation and its basic function. Neuropsychopharmacology. 2013;38(1):23–38. Mueller BR, Bale TL. Sex-specific programming of offspring emotionality after stress early in pregnancy. J Neurosci. 2008;28(36):9055–65. Murphy YE, Flessner CA. Family functioning in paediatric obsessive compulsive and related disorders. Br J Clin Psychol. 2015;54(4):414–34. Pampaloni I, Marriott S, Pessina E, Fisher C, Govender A, Mohamed H, Chandler A, Tyagi H, Morris L, Pallanti S. The global assessment of OCD. Compr Psychiatry. 2022;118:152342. Peris TS, Rozenman M, Gonzalez A, Vreeland A, Piacentini J, Tan PZ, Ricketts EJ. Family functioning in pediatric trichotillomania, obsessive compulsive disorder, and healthy comparison youth. Psychiatry Res. 2019;281:112578. Richter J, Eisemann M, Richter G. Perceived parental rearing and state versus trait aspects of adult depression. Psychopathology. 1991;24(1):25–30. Stein DJ, Kogan CS, Atmaca M, Fineberg NA, Fontenelle LF, Grant JE, Matsunaga H, Reddy YCJ, Simpson HB, Thomsen PH, van den Heuvel OA, Veale D, Woods DW, Reed GM. The classification of Obsessive-Compulsive and Related Disorders in the ICD-11. J Affect Disord. 2016;190:663–74. Shabanpour R, Zahiroddin AR, Janbozorgi M, Ghaeli P. Assessment of Defense Styles and Mechanisms in Iranian Patients Suffering from Obsessive Compulsive or Panic Disorders versus Normal Controls using Persian Version of Defense Style Questionnaire-40. Iran J Psychiatry. 2012 Winter;7(1):31–5. Shen T, Li X, Chen L, Chen Z, Tan T, Hua T, Chen B, Yuan Y, Zhang Z, Kuney L, Xu Z. The relationship of tryptophan hydroxylase-2 methylation to early-life stress and its impact on short-term antidepressant treatment response. J Affect Disord. 2020;276:850–8. Smári J, Martinsson DR, Einarsson H. Rearing practices and impulsivity/hyperactivity symptoms in relation to inflated responsibility and obsessive-compulsive symptoms. Scand J Psychol. 2010;51(5):392–7. Tan T, Xu Z, Gao C, Shen T, Li L, Chen Z, Chen L, Xu M, Chen B, Liu J, Zhang Z, Yuan Y. Influence and interaction of resting state functional magnetic resonance and tryptophan hydroxylase-2 methylation on short-term antidepressant drug response. BMC Psychiatry. 2022;22(1):218. Thienemann M, Shaw RJ, Steiner H. Defense style and family environment. Child Psychiatry Hum Dev. 1998 Spring;28(3):189–98. Toro J, Cervera M, Osejo E, Salamero M. Obsessive-compulsive disorder in childhood and adolescence: a clinical study. J Child Psychol Psychiatry. 1992;33(6):1025–37. Walther DJ, Bader M. A unique central tryptophan hydroxylase isoform. Biochem Pharmacol. 2003;66(9):1673–80. Wang J, Zhao X. Comparison of family functioning and social support between families with a member who has obsessive-compulsive disorder and control families in Shanghai. Shanghai Arch Psychiatry. 2012;24(1):20–9. Wang L, Chen Y, Wang M, Zhao C, Qiao D. Relationship between gene-environment interaction and obsessive-compulsive disorder: A systematic review. J Psychiatr Res. 2023;164:281–90. Zhang L, Wang H, Abel GM, Storm DR, Xia Z. The Effects of Gene-Environment Interactions Between Cadmium Exposure and Apolipoprotein E4 on Memory in a Mouse Model of Alzheimer's Disease. Toxicol Sci. 2020;173(1):189–201. Zhang X, Gainetdinov RR, Beaulieu JM, Sotnikova TD, Burch LH, Williams RB, Schwartz DA, Krishnan KR, Caron MG. Loss-of-function mutation in tryptophan hydroxylase-2 identified in unipolar major depression. Neuron. 2005;45(1):11–6. Zhang Y, Chang Z, Chen J, Ling Y, Liu X, Feng Z, Chen C, Xia M, Zhao X, Ying W, Qing X, Li G, Zhang C. Methylation of the tryptophan hydroxylase–2 gene is associated with mRNA expression in patients with major depression with suicide attempts. Mol Med Rep. 2015;12(2):3184–90. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 30 Sep, 2025 Read the published version in BMC Psychiatry → Version 1 posted Editorial decision: Revision requested 28 Jan, 2025 Reviews received at journal 16 Jan, 2025 Reviewers agreed at journal 10 Jan, 2025 Reviews received at journal 11 Oct, 2024 Reviewers agreed at journal 18 Sep, 2024 Reviewers invited by journal 04 Sep, 2024 Editor assigned by journal 04 Jul, 2024 Editor invited by journal 11 Apr, 2024 Submission checks completed at journal 11 Apr, 2024 First submitted to journal 10 Apr, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4247451","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":291057354,"identity":"e62fbeb0-25c1-411b-a347-7aeaa7dd4b87","order_by":0,"name":"Lina Wang","email":"","orcid":"","institution":"Shandong Normal University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Lina","middleName":"","lastName":"Wang","suffix":""},{"id":291057355,"identity":"72ad3d3e-f49a-4977-894e-e0ae406a8b65","order_by":1,"name":"Yu Chen","email":"","orcid":"","institution":"National Clinical Research Center for Mental Disorders \u0026 National Center for Mental Disorders, Capital Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Yu","middleName":"","lastName":"Chen","suffix":""},{"id":291057356,"identity":"5456ea5a-33cd-496d-bef2-04652ce91f63","order_by":2,"name":"Shiqi Hu","email":"","orcid":"","institution":"Shandong Mental Health Center","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Shiqi","middleName":"","lastName":"Hu","suffix":""},{"id":291057357,"identity":"8ff48c43-92f8-4f8d-ba0c-3c4dd2427d51","order_by":3,"name":"Tiangui Yu","email":"","orcid":"","institution":"Shandong Mental Health Center","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Tiangui","middleName":"","lastName":"Yu","suffix":""},{"id":291057358,"identity":"d3ec52b0-c65d-4a34-8b79-acc759594b0c","order_by":4,"name":"Zhenhua Liu","email":"","orcid":"","institution":"Shandong Mental Health Center","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Zhenhua","middleName":"","lastName":"Liu","suffix":""},{"id":291057359,"identity":"4b30f012-1e9d-4bae-8934-cbb9057b6137","order_by":5,"name":"Dongdong Qiao","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0ElEQVRIiWNgGAWjYDACZhBhAGYyPkioqCFJCzOzwYMzx0izj03yYQszYXV8x5kfPuYpuCPPL91/rCKxgY2Bv707Aa8WycNsxsY8Bs8MZ845zHYjcYcMg8SZsxvwajE4zGAmOcPgcILBjWSgljNsDAYSuYS0sH8Da7EHailIbGMmRguPmcQHkC0SyWwMRGmRPMxTbADUYjjjRrKxRMKZYzwE/cJ3/vjGBwl/Dsvzz0h8+PFHRY0cf3svfi0MB9D4PPiVY9MyCkbBKBgFowADAADGEkbq+rhmOwAAAABJRU5ErkJggg==","orcid":"","institution":"Shandong Mental Health Center","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Dongdong","middleName":"","lastName":"Qiao","suffix":""}],"badges":[],"createdAt":"2024-04-10 12:43:01","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4247451/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4247451/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12888-025-07217-0","type":"published","date":"2025-09-30T15:58:12+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":92884482,"identity":"be3d17ec-0b4c-43ab-9d9d-afc2f80f3d9a","added_by":"auto","created_at":"2025-10-06 16:13:18","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":854390,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4247451/v1/40658952-12c4-4636-9b56-ae281a210854.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Exploring the Influence of DNA Methylation and family factors on OCD and symptoms Severity: Insights into the TPH2 Gene","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eObsessive-compulsive disorder (OCD) is a neuropsychiatric disorder characterized by obsessive thoughts and compulsive behavior, which seriously damages patients' quality of life and brings severe financial and emotional stress to families and society (Pampaloni I et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Hirschtritt ME et al.,2017). The disability-adjusted life years (DALYs) of OCD are more than those of sclerosis and Parkinson's disease combined (Goodman WK et al.,2014). To date, OCD has received increasing attention because of the severe damage it can cause to individuals, but its etiology is not yet fully understood. Genetic and environmental factors may have varying degrees of risk for the onset and development of OCD (Toro J et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e1992\u003c/span\u003e; Murphy YE et al., 2015). Parenting styles and family functioning have been studied as one or more dimensions of family factors associated with OCD. Parents of OCD patients showed similar features in parenting styles regarding severity, excessive involvement, and lack of warmth (Mathieu SL et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Aspects of family functioning such as Affective Responsiveness, Communication, and Problem Solving may be involved in the development of OCD as studies have shown that these factors were related to the severity of symptoms (Alonso P et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Sm\u0026aacute;ri J et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Lennertz L et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Haciomeroglu B et al., 2014).\u003c/p\u003e \u003cp\u003eThe view on gene-environment interactions (G\u0026times;E) suggests that risk factors, whether genetic or environmental, play a probabilistic rather than a deterministic role in disease (Assary E et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). According to a recent systematic review, G\u0026times;E is associated with susceptibility, clinical characteristics, and treatment response in OCD (Wang L \u0026amp; Chen Y et al., \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Epigenetic mechanisms are a vital part of the G\u0026times;E system, and epigenetic modifications are dynamic and can be changed by environmental factors, such that they constitute a molecular basis underlying GxE interactions (Feinberg ME et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Jirtle et al. MK, 2007; Bollati V \u0026amp; Baccarelli A et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Zhang L et al., \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). DNA methylation is an essential epigenetic modification in the human genome, which can dynamically control gene expression (Liu C et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Neuronal activity could modulate the pattern of DNA methylation in response to physiological and environmental stimuli (Martinowich K et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2003\u003c/span\u003e; Guo ZY et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). DNA methylation in different genomic regions may influence gene activities based on the underlying genetic sequence (Moore LD et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2013\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eTryptophan hydroxylase-2 (TPH2) is predominantly expressed in the brain, which is a second, neuron-specific TPH isoform, the rate-limiting enzyme in 5-Hydroxytryptamine (5-HT) biosynthesis (Chen GL \u0026amp; Miller GM et al., 2012). TPH2 was found mainly in the brain stem and was encoded by the TPH2 gene located on human chromosome 12 and mouse chromosome 10 (Walther DJ et al., 2003). On the one hand, TPH2 gene expression is influenced by genetic factors, and studies have shown that a functional polymorphism of the TPH2 gene could affect the synthesis and transmission of 5-HT in the nervous system (Zhang X et al., \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Jacobsen JP et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Gutknecht L et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). On the other hand, researchers have proposed that TPH2 gene expression is tissue-specific and responsive to stressors (Gardner KL et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Mueller BR \u0026amp; Bale TL, 2008). Previous studies suggested that TPH2 regulation of the midbrain saber synapse played an essential role in the pathogenesis of OCD (M\u0026ouml;ssner R et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2006\u003c/span\u003e) and that TPH2 gene expression was closely associated with epigenetic mechanisms (Chen GL et al., 2012). Thus, epigenetic alterations in the TPH2 gene may play a role in OCD.\u003c/p\u003e \u003cp\u003eThis study aimed to investigate the role of TPH2 gene DNA methylation in the onset and development of OCD. Meanwhile, the relationship among DNA methylation of the TPH2 gene, family factors (parenting styles and family functioning), and the clinical characteristics of OCD has been explored.\u003c/p\u003e"},{"header":"2. Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Participants\u003c/h2\u003e \u003cp\u003eThis study is a cross-sectional study. The case group was recruited from the inpatient department of Shandong Mental Health Centre between September 2019 and January 2022. Patients were included according to the following criteria: 1) meeting the diagnostic criteria for OCD in the 10th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-10); 2) age 10\u0026ndash;65 years, male or female; 3) biological parents of Han Chinese ethnicity. Exclusion criteria included: 1) major physical illness related to the circulatory, urinary, hematological, or motor systems; 2) previous or existing organic brain disease or endocrine system disease; 3) concomitant psychoactive substance abuse; 4) pregnant and lactating women; 5) history of diagnosis for any other mental disorders. An age- and gender-matched control group was recruited from the community. All participants voluntarily declared their consent to participate in this study. The Ethics Committee of Shandong Mental Health Center granted ethical approval.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Assessments\u003c/h2\u003e \u003cp\u003eA concise, self-made questionnaire was used to record the sociodemographic data of the age and gender of all the participants. In patients, OCD severity was assessed via the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), with items 1\u0026ndash;5 reflecting symptoms related to obsessions and items 6\u0026ndash;10 related to compulsions (Goodman WK et al.,1989). Parenting attitudes and behaviors were assessed quantitatively using the Egna Minnen Barndoms Uppfostran (EMBU), and factor analysis of the EMBU identified the following four primary dimensions: rejection, emotional warmth, overprotection, and favoring subject (Richter J et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e1991\u003c/span\u003e; Benjaminsen S et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e1984\u003c/span\u003e). The Family Assessment Device (FAD) was used to assess the functioning of the family system in which the individual lives which was divided into seven subscales, including problem solving, communication, roles, affective responsiveness, affective involvement, behavior control, and general functioning. FAD is a comprehensive assessment of the state of family relationships and the ability to adapt to changing social circumstances (Peris TS et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3. DNA extraction\u003c/h2\u003e \u003cp\u003eDNA extraction was done based on peripheral venous blood samples from patients with OCD and controls. The peripheral blood was collected at 7:00 am after fasting for at least eight hours using EDTA anticoagulation tubes and then centrifuged at 3000 rpm for 10 minutes. Immediately after centrifugation, the middle layer of leukocytes was extracted and stored in EP tubes at -80\u0026deg;C in the refrigerator until use. DNA extraction was performed using a medium-volume whole-blood DNA extraction kit provided by BioTeKe Corporation. Primer synthesis provided by Thermo Fisher detected the DNA methylation, and Zymo and Agena provided the Methylated DNA Nitrite Kit and EpiTYPER\u0026trade; Reagent Kit, respectively. The DNA methylation levels were quantified through the Agena MassArray DNA flight mass spectrometry system and polymerase chain reaction (PCR) by Beijing Liuhe Huada Gene Technology Co.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4. Determination of DNA methylation level\u003c/h2\u003e \u003cp\u003eIn this study, the screening of CpG sites in the promoter region of the TPH2 gene was performed by the online prediction website (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://www.ebi.ac.uk/Tools/seqstats/emboss_cpgplot\u003c/span\u003e\u003cspan address=\"http://www.ebi.ac.uk/Tools/seqstats/emboss_cpgplot\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e). A total of 13 CpG sites were identified, among which CpG site 1, CpG site 3, and CpG site 8 fragments were found to have the same molecular weight and product peaks after enzymatic digested by MassArray system and Polymerase Chain Reaction (PCR), so they were combined as CpG site 1,3,8 (Ellis JA \u0026amp; Ong B, 2017). CpG site 13 was not provided due to problems with the sequence.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5. Statistical analysis\u003c/h2\u003e \u003cp\u003eThe statistical data were analyzed by using SPSS 27.0 software. The Shapiro-Wilk test was used to examine the normality of each variable. The Chi-square test was applied to investigate group differences when the dependent variable was measured at a nominal level. The t-test was carried out to compare means between two independent groups. The binary logistic regression analysis model was used to analyze the risk or protective factors that predicted the occurrence of OCD. Spearman's rank correlation was used to explore the correlation. The significance level was set at \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e3.1 General information of participants\u003c/h2\u003e \u003cp\u003eA total of 88 patients (52 males and 36 females, mean age\u0026thinsp;\u0026plusmn;\u0026thinsp;SD: 24.64\u0026thinsp;\u0026plusmn;\u0026thinsp;13.73 years) were enrolled in this study. The control group comprised 94 healthy individuals (50 males and 44 females, mean age\u0026thinsp;\u0026plusmn;\u0026thinsp;SD: 26.06\u0026thinsp;\u0026plusmn;\u0026thinsp;9.85 years). There were no statistical differences in age and gender between the two groups \u003cb\u003e(\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSample sizes and demographics in case and control groups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePatients (n\u0026thinsp;=\u0026thinsp;88)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eControls (n\u0026thinsp;=\u0026thinsp;94)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003et /χ\u0026sup2;\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003cp\u003eGender (Male/Female)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e24.64\u0026thinsp;\u0026plusmn;\u0026thinsp;13.73\u003c/p\u003e \u003cp\u003e52/36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e26.06\u0026thinsp;\u0026plusmn;\u0026thinsp;9.85\u003c/p\u003e \u003cp\u003e50/44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.810\u003c/p\u003e \u003cp\u003e0.642\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.419\u003c/p\u003e \u003cp\u003e0.423\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Comparison of DNA methylation levels in patients and controls\u003c/h2\u003e \u003cp\u003eThe DNA methylation levels at different CpG sites in the promoter region of the TPH2 gene were compared between patients and controls. The results in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e showed that the DNA methylation levels at CpG site 6 were positively associated with OCD (B\u0026thinsp;=\u0026thinsp;3.261, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.045), while the levels at CpG site 5 were negatively correlated with OCD (B = -11.856, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001). However, only the difference of CpG site 5 remained significant after Bonferroni correction (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.005 correcting for 10 tests). In other words, DNA methylation at this site of the TPH2 gene was a \u0026ldquo;protective\u0026rdquo; factor for the onset of OCD (the result remained significant, rectified by age and gender).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of DNA methylation levels between groups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"15\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c15\" colnum=\"15\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c5\" namest=\"c2\"\u003e \u003cp\u003ePatients\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e \u003cp\u003eControls\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c14\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c15\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCpG sites\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMax\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eMax\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eMin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eSD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003eSE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003ez value\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e \u003cp\u003eOR\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003eOR(95%CI)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCpG_1,3,8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-0.259\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e2.069\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e0.016\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e0.900\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e \u003cp\u003e0.772\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e0.013\u0026thinsp;~\u0026thinsp;44.560\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCpG_2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-1.480\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e2.135\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e0.480\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e0.488\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e \u003cp\u003e0.228\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e0.003\u0026thinsp;~\u0026thinsp;14.959\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCpG_4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-1.366\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0.865\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e2.496\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e0.114\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e \u003cp\u003e0.255\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e0.047\u0026thinsp;~\u0026thinsp;1.389\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCpG_5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-11.856\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e3.604\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e10.822\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e0.001**\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e \u003cp\u003e0.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e0.000\u0026thinsp;~\u0026thinsp;0.008\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCpG_6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e3.261\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e1.627\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e4.016\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e0.045*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e \u003cp\u003e26.072\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e1.074\u0026thinsp;~\u0026thinsp;632.729\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCpG_7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-0.992\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e3.077\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e0.104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e0.747\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e \u003cp\u003e0.371\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e0.001\u0026thinsp;~\u0026thinsp;154.379\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCpG_9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e3.982\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e4.328\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e0.847\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e0.357\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e \u003cp\u003e53.643\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e0.011\u0026thinsp;~\u0026thinsp;259047.654\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCpG_10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-2.175\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e4.069\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e0.286\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e0.593\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e \u003cp\u003e0.114\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e0.000\u0026thinsp;~\u0026thinsp;330.553\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCpG_11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.038\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e1.909\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e0.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e0.984\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e \u003cp\u003e1.038\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e0.025\u0026thinsp;~\u0026thinsp;43.767\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCpG_12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-0.683\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e1.213\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e0.317\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e0.573\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c14\"\u003e \u003cp\u003e0.505\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e0.047\u0026thinsp;~\u0026thinsp;5.439\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eMax, maximum; Min, minimum; M, mean; SD, standard deviation. *\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05, **\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Relationship between epigenetic and environmental factors in OCD patients\u003c/h2\u003e \u003cp\u003eA total of 41 OCD patients completed the EMBU and FAD scales and their symptom severity was evaluated by the Y-BOCS. The relationship between family factors (EMBU, FAD) and twelve CpG sites of the TPH2 gene was then analyzed using Spearman's rank correlation. Results showed that the DNA methylation levels at CpG site 2 were negatively associated with general functioning of FAD (\u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003eρ\u003c/em\u003e\u003c/sub\u003e = -0.345, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.027) and positively correlated with maternal emotional warmth of EMBU (\u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003eρ\u003c/em\u003e\u003c/sub\u003e = 0.352, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.024) in patients. In contrast, the maternal emotional warmth was negatively associated with the DNA methylation levels of CpG site 1,3,8 (\u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003eρ\u003c/em\u003e\u003c/sub\u003e = -0.338, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.031). The DNA methylation levels at CpG site 5 and site 12 were positively related to the paternal and maternal favoring subject of EMBU (\u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003eρ\u003c/em\u003e\u003c/sub\u003e = 0.380, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.014; \u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003eρ\u003c/em\u003e\u003c/sub\u003e = 0.327, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.037), respectively. The results also revealed that Problem Solving of FAD was positively associated with the DNA methylation at CpG site 9 (\u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003eρ\u003c/em\u003e\u003c/sub\u003e = 0.361, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.021). No other association was found between the investigated environmental factors, and patients\u0026rsquo; epigenetic alteration. Detailed results are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eRelationship between Family factors and DNA methylation levels in patients\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"11\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003ePaternal\u003c/p\u003e \u003cp\u003efavoring subject\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eMaternal\u003c/p\u003e \u003cp\u003eemotional warmth\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003eMaternal\u003c/p\u003e \u003cp\u003efavoring subject\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003eProblem solving\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e \u003cp\u003eGeneral Functioning\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eSperaman's ρ\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eSperaman's ρ\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003eSperaman's ρ\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cem\u003eSperaman's ρ\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e\u003cem\u003eSperaman's ρ\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCpG_1,3,8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.174\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.277\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.338\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.031*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.027\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.868\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.097\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.548\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.268\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0.090\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCpG_2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.018\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.912\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.352\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.024*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.158\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.324\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.033\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.839\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-0.345\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0.027*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCpG_5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.380\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.014*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.145\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.366\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.255\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.108\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-0.086\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.594\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-0.168\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0.293\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCpG_9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.102\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.526\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.038\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.815\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-0.026\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.872\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.361\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.021*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.228\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0.151\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCpG_12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.215\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.177\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.142\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.376\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.327\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.037*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-0.066\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.682\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-0.073\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0.651\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"11\"\u003e*\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Association of epigenetic and environmental factors with OCD symptoms severity\u003c/h2\u003e \u003cp\u003eSpearman's rank correlation was also applied to analyze the effect of epigenetic, and environmental factors on the severity of OCD symptoms. As Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e showed, obsessive thoughts were negatively associated with paternal emotional warmth of EMBU (\u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003eρ\u003c/em\u003e\u003c/sub\u003e = -0.327, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.037); and the scores of compulsive behaviors and Y-BOCS total scores were negatively related to the DNA methylation levels at CpG site 2 (\u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003eρ\u003c/em\u003e\u003c/sub\u003e = -0.436, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.004; \u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003eρ\u003c/em\u003e\u003c/sub\u003e = -0.489, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001) while positively related to the levels at CpG site 1,3,8, (r\u003csub\u003eρ\u003c/sub\u003e= 0.331, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.035; \u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003eρ\u003c/em\u003e\u003c/sub\u003e = 0.311, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.048). Meanwhile, Y-BOCS total scores was positively associated with the methylation levels at CpG site 10 (\u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003eρ\u003c/em\u003e\u003c/sub\u003e = 0.326, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.037). There was no other significant association between the analyzed Y-BOCS scores and the family (EMBU, FAD) factors and epigenetic alteration.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAssociation of Family factors and DNA methylation levels with symptoms severity\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003ePaternal emotional warmth\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eCpG_1,3,8\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003eCpG_2\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003eCpG_10\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eSperaman's ρ\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eSperaman's ρ\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003eSperaman's ρ\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cem\u003eSperaman's ρ\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eObsessive thoughts\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.327\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.037*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.051\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.753\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-0.088\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.586\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-0.036\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.824\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCompulsive behaviors\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.129\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.421\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.331\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.035*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-0.436\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.004**\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.306\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.051\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eY-BOCS total scores\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.253\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.111\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.311\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.048*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-0.489\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.001**\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.326\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.037*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"9\"\u003e*\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05, **\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.01\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eIn this study, the association among DNA methylation of the TPH2 gene, family psychological characteristics (parenting style, family functioning), and OCD was investigated. We found that the DNA methylation levels at CpG site 5 and site 6 of the TPH2 gene promoter region was correlated with OCD susceptibility, while only CpG site 5 remained to have the negative association after multiple corrections. DNA methylation levels at different CpG sites (CpG site 1,3,8, CpG site 2, CpG site 5, CpG site 9, CpG site 12) were associated with various factors of family psychological characteristics in patients. In addition, the DNA methylation levels (CpG site 1,3,8, CpG site 2, CpG site 10) and paternal emotional warmth of EMBU were found to be related to the symptoms severity of OCD.\u003c/p\u003e \u003cp\u003eThis study suggested that the DNA methylation of CpG site 5 may act as a \u0026ldquo;protective\u0026rdquo; factor against the onset of OCD. Although not related to symptom severity, it was found to be positively associated with the paternal favoring parenting style in OCD patients. A similar positive correlation was observed between maternal favoring subjects and DNA methylation of CpG site 12. Previous studies have indicated that the onset and severity of OCD, as well as its co-morbidity, were negatively correlated with positive parenting styles (such as emotional warmth and preference) of fathers (Alonso P et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Mathieu SL et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), which may be consistent with our findings. Considering previous research showing that TPH2 expression was regulated by DNA methylation of the TPH2 gene promoter region in patients with major depressive disorder (MDD) (Zhang Y et al., \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), and based on the hypothetical assumption of a serotonin imbalance (Hirschtritt ME et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), the results of this study suggest a possible neurogenetic mechanism. Specifically, an upbeat paternal parenting style may reduce the risk of developing OCD by promoting DNA methylation of CpG sites in the TPH2 gene.\u003c/p\u003e \u003cp\u003eThe promoter region of the TPH2 gene contains several scattered CpG sites rather than CpG islands (Chen GL \u0026amp; Miller GM, 2012). Studies have demonstrated that regulatory polymorphisms of TPH2 may differentially influence the response to environmental factors, presumably due to their differential roles in gene expression regulation (Shen T et al., \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Tan T et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Similarly, our findings suggested that the onset and development of OCD may be regulated by DNA methylation at different CpG sites of the TPH2 gene. We observed that the DNA methylation level at CpG site 2 was positively correlated with maternal emotional warmth but negatively correlated with the patients' compulsive behaviors and the Y-BOCS total scores. However, the DNA methylation levels of CpG sites 1, 3, 8 exhibited results that were contrary to those of CpG site 2. In addition, paternal emotional warmth was found to be negatively associated with obsessions. A previous study revealed that patients with OCD reported less parental emotional warmth and more control and rejection than healthy individuals (Lennertz L et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). Parental emotional warmth had a negative association with clinical features of OCD (Mathieu SL et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Thus, we hypothesize that positive parenting styles, such as parental emotional warmth, may be linked with OCD severity through the epigenetic modification of the TPH2 gene in patients.\u003c/p\u003e \u003cp\u003eRegarding the association between family functioning and OCD, patients were found to reported significantly poorer family functioning, excluding the Affective Involvement dimension, as assessed by FAD (Wang J \u0026amp; Zhao X, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). The general functioning dimension of FAD is utilized to assess individuals' overall level of family functioning, with higher scores indicating lower levels of social support (Cong CW et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Although general functioning did not exhibit a correlation with OCD severity in this study, it was negatively correlated with the DNA methylation level of CpG site 2, which, in turn, was negatively correlated with compulsive scores and the Y-BOCS total score in this study. Therefore, a hypothesis has been posited that general functioning may impact the progression of OCD through involvement in the epigenetic modulation of the TPH2, which requires validation in a larger sample size. Problem solving dimension refers to the family's capacity to address issues while maintaining an adequate level of family functioning, which is relevant to the risk and maintenance of anorexia nervosa (AN) (Monteleone AM et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). A novel finding from our study was that problem solving of FAD was positively associated with the DNA methylation levels of CpG site 9. Since this site did not exhibit a correlation with OCD, further investigation is warranted to determine whether and how this association with problem solving affects OCD.\u003c/p\u003e \u003cp\u003eThis study is subject to several limitations. Firstly, the sample size was modest, which may have resulted in a relatively low statistical power. Secondly, the quantification of family factors relied on information obtained from scales, which could introduce bias in the recall and reporting of the individuals tested. Thirdly, the patients with OCD included in this study were all hospitalized, so our findings may not be generalized to outpatients or those who do not seek therapy. OCD is a complex disease with pathogenesis potentially influenced by numerous factors. Therefore, further multi-omics studies based on larger sample sizes and investigations into the role of multifactor gene-environment interactions in OCD are warranted.\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eIn summary, the present study was the first to investigate the relationship between DNA methylation in the TPH2 gene, family factors, and the onset and progression of OCD. It is suggested that DNA methylation at distinct CpG sites could have varying impacts on the occurrence and course of OCD. Family factors may influence OCD through their impact on DNA methylation of the TPH2 gene.\u003c/p\u003e"},{"header":"Declarations","content":" \u003cp\u003e \u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e \u003cp\u003e This study was conducted in accordance with the Declaration of Helsinki. And the study was approved by the Ethics Committee of Shandong Mental Health Center (No. 2020R38). An informed consent was signed by each participant before participating in this study. We confirmed that all methods were performed in accordance with the relevant guidelines and regulations.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent for publications\u003c/strong\u003e \u003cp\u003eNot applicable.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eCompeting interests\u003c/h2\u003e \u003cp\u003eThe authors have no actual or potential conflicts of interest to declare.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis study was funded by Shandong Province Key R\u0026amp;D Program Project (2016GSF201200) and Shandong Province Key R\u0026amp;D Program (Science and Technology Demonstration Project) Project (2021SFGC0504). The funding bodies played no role in the design of the study and collection, analysis, and interpretation of data or in writing the manuscript.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eDongdong Qiao and Lina Wang designed the study; Lina Wang and Zhenhua Liu were responsible for the clinical diagnosis; Yu Chen and Shiqi Hu conducted sample collection, performed the experiments and analyzed the data; Lina Wang, Yu Chen and Zhenhua Liu were responsible for manuscript writing; Tiangui Yu and Dongdong Qiao supervised the study. All authors have read and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eWe thank all the participants for their support in this study.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eResearchers interested in this study may contact corresponding author to obtain relevant data via email: [email protected].\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAlonso P, Mench\u0026oacute;n JM, Mataix-Cols D, Pifarr\u0026eacute; J, Urretavizcaya M, Crespo JM, Jim\u0026eacute;nez S, Vallejo G, Vallejo J. Perceived parental rearing style in obsessive-compulsive disorder: relation to symptom dimensions. Psychiatry Res. 2004;127(3):267\u0026ndash;78.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAssary E, Vincent JP, Keers R, Pluess M. Gene-environment interaction and psychiatric disorders: Review and future directions. Semin Cell Dev Biol. 2018;77:133\u0026ndash;43.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBollati V, Baccarelli A, Sartori S, Tarantini L, Motta V, Rota F, Costa G. Epigenetic effects of shiftwork on blood DNA methylation. Chronobiol Int. 2010;27(5):1093\u0026ndash;104.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBenjaminsen S, J\u0026oslash;rgensen J, Kragh-Hansen L, Pedersen LL. Memories of parental rearing practices and personality features. Acta Psychiatr Scand. 1984;69(5):426\u0026ndash;34.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen GL, Miller GM. Advances in tryptophan hydroxylase-2 gene expression regulation: new insights into serotonin-stress interaction and clinical implications. Am J Med Genet B Neuropsychiatr Genet. 2012;159B(2):152\u0026ndash;71.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCong CW, Tan SA, Nainee S, Tan CS. Psychometric Qualities of the McMaster Family Assessment Device-General Functioning Subscale for Malaysian Samples. Int J Environ Res Public Health. 2022;19(4):2440.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEllis JA, Ong B. The MassARRAY\u0026reg; System for Targeted SNP Genotyping. Methods Mol Biol. 2017;1492:77\u0026ndash;94.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFeinberg ME, Button TM, Neiderhiser JM, Reiss D, Hetherington EM. Parenting and adolescent antisocial behavior and depression: evidence of genotype x parenting environment interaction. Arch Gen Psychiatry. 2007;64(4):457\u0026ndash;65.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGardner KL, Hale MW, Oldfield S, Lightman SL, Plotsky PM, Lowry CA. Adverse experience during early life and adulthood interact to elevate tph2 mRNA expression in serotonergic neurons within the dorsal raphe nucleus. Neuroscience. 2009;163(4):991\u0026ndash;1001.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGoodman WK, Price LH, Rasmussen SA, Mazure C, Fleischmann RL, Hill CL, Heninger GR, Charney DS. The Yale-Brown Obsessive Compulsive Scale. I. Development, use, and reliability. Arch Gen Psychiatry. 1989;46(11):1006\u0026ndash;11.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGoodman WK, Grice DE, Lapidus KA, Coffey BJ. Obsessive-compulsive disorder. Psychiatr Clin North Am. 2014;37(3):257\u0026ndash;67.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGuo ZY, Hao XH, Tan FF, Pei X, Shang LM, Jiang XL, Yang F. The elements of human cyclin D1 promoter and regulation involved. Clin Epigenetics. 2011;2(2):63\u0026ndash;76.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGutknecht L, Waider J, Kraft S, Kriegebaum C, Holtmann B, Reif A, Schmitt A, Lesch KP. Deficiency of brain 5-HT synthesis but serotonergic neuron formation in Tph2 knockout mice. J Neural Transm (Vienna). 2008;115(8):1127\u0026ndash;32.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHaciomeroglu B, Karanci AN. Perceived parental rearing behaviours, responsibility attitudes and life events as predictors of obsessive compulsive symptomatology: test of a cognitive model. Behav Cogn Psychother. 2014;42(6):641\u0026ndash;52.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHirschtritt ME, Bloch MH, Mathews CA. Obsessive-Compulsive Disorder: Advances in Diagnosis and Treatment. JAMA. 2017;317(13):1358\u0026ndash;67.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJacobsen JP, Siesser WB, Sachs BD, Peterson S, Cools MJ, Setola V, Folgering JH, Flik G, Caron MG. Deficient serotonin neurotransmission and depression-like serotonin biomarker alterations in tryptophan hydroxylase 2 (Tph2) loss-of-function mice. Mol Psychiatry. 2012;17(7):694\u0026ndash;704.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJirtle RL, Skinner MK. Environmental epigenomics and disease susceptibility. Nat Rev Genet. 2007;8(4):253\u0026ndash;62.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLennertz L, Grabe HJ, Ruhrmann S, Rampacher F, Vogeley A, Schulze-Rauschenbach S, Ettelt S, Meyer K, Kraft S, Reck C, Pukrop R, John U, Freyberger HJ, Klosterk\u0026ouml;tter J, Maier W, Falkai P, Wagner M. Perceived parental rearing in subjects with obsessive-compulsive disorder and their siblings. Acta Psychiatr Scand. 2010;121(4):280\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu C, Jiao C, Wang K, Yuan N. DNA Methylation and Psychiatric Disorders. Prog Mol Biol Transl Sci. 2018;157:175\u0026ndash;232.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMartinowich K, Hattori D, Wu H, Fouse S, He F, Hu Y, Fan G, Sun YE. DNA methylation-related chromatin remodeling in activity-dependent BDNF gene regulation. Science. 2003;302(5646):890\u0026ndash;3.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMathieu SL, Conlon EG, Waters AM, Farrell LJ. Perceived Parental Rearing in Paediatric Obsessive-Compulsive Disorder: Examining the Factor Structure of the EMBU Child and Parent Versions and Associations with OCD Symptoms. Child Psychiatry Hum Dev. 2020;51(6):956\u0026ndash;68.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMonteleone AM, Marchetto C, Cascino G, Criscuolo M, Carfagno M, Castiglioni MC, Caramadre A, Barone E, Zanna V. The bidirectional connection between family functioning and psychopathology: A network analysis in a large sample of adolescents with anorexia nervosa and their parents. Fam Process. 2024 Mar 13.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eM\u0026ouml;ssner R, Walitza S, Geller F, Scherag A, Gutknecht L, Jacob C, Bogusch L, Remschmidt H, Simons M, Herpertz-Dahlmann B, Fleischhaker C, Schulz E, Warnke A, Hinney A, Wewetzer C, Lesch KP. Transmission disequilibrium of polymorphic variants in the tryptophan hydroxylase-2 gene in children and adolescents with obsessive-compulsive disorder. Int J Neuropsychopharmacol. 2006;9(4):437\u0026ndash;42.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMoore LD, Le T, Fan G. DNA methylation and its basic function. Neuropsychopharmacology. 2013;38(1):23\u0026ndash;38.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMueller BR, Bale TL. Sex-specific programming of offspring emotionality after stress early in pregnancy. J Neurosci. 2008;28(36):9055\u0026ndash;65.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMurphy YE, Flessner CA. Family functioning in paediatric obsessive compulsive and related disorders. Br J Clin Psychol. 2015;54(4):414\u0026ndash;34.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePampaloni I, Marriott S, Pessina E, Fisher C, Govender A, Mohamed H, Chandler A, Tyagi H, Morris L, Pallanti S. The global assessment of OCD. Compr Psychiatry. 2022;118:152342.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePeris TS, Rozenman M, Gonzalez A, Vreeland A, Piacentini J, Tan PZ, Ricketts EJ. Family functioning in pediatric trichotillomania, obsessive compulsive disorder, and healthy comparison youth. Psychiatry Res. 2019;281:112578.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRichter J, Eisemann M, Richter G. Perceived parental rearing and state versus trait aspects of adult depression. Psychopathology. 1991;24(1):25\u0026ndash;30.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStein DJ, Kogan CS, Atmaca M, Fineberg NA, Fontenelle LF, Grant JE, Matsunaga H, Reddy YCJ, Simpson HB, Thomsen PH, van den Heuvel OA, Veale D, Woods DW, Reed GM. The classification of Obsessive-Compulsive and Related Disorders in the ICD-11. J Affect Disord. 2016;190:663\u0026ndash;74.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShabanpour R, Zahiroddin AR, Janbozorgi M, Ghaeli P. Assessment of Defense Styles and Mechanisms in Iranian Patients Suffering from Obsessive Compulsive or Panic Disorders versus Normal Controls using Persian Version of Defense Style Questionnaire-40. Iran J Psychiatry. 2012 Winter;7(1):31\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShen T, Li X, Chen L, Chen Z, Tan T, Hua T, Chen B, Yuan Y, Zhang Z, Kuney L, Xu Z. The relationship of tryptophan hydroxylase-2 methylation to early-life stress and its impact on short-term antidepressant treatment response. J Affect Disord. 2020;276:850\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSm\u0026aacute;ri J, Martinsson DR, Einarsson H. Rearing practices and impulsivity/hyperactivity symptoms in relation to inflated responsibility and obsessive-compulsive symptoms. Scand J Psychol. 2010;51(5):392\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTan T, Xu Z, Gao C, Shen T, Li L, Chen Z, Chen L, Xu M, Chen B, Liu J, Zhang Z, Yuan Y. Influence and interaction of resting state functional magnetic resonance and tryptophan hydroxylase-2 methylation on short-term antidepressant drug response. BMC Psychiatry. 2022;22(1):218.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eThienemann M, Shaw RJ, Steiner H. Defense style and family environment. Child Psychiatry Hum Dev. 1998 Spring;28(3):189\u0026ndash;98.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eToro J, Cervera M, Osejo E, Salamero M. Obsessive-compulsive disorder in childhood and adolescence: a clinical study. J Child Psychol Psychiatry. 1992;33(6):1025\u0026ndash;37.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWalther DJ, Bader M. A unique central tryptophan hydroxylase isoform. Biochem Pharmacol. 2003;66(9):1673\u0026ndash;80.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang J, Zhao X. Comparison of family functioning and social support between families with a member who has obsessive-compulsive disorder and control families in Shanghai. Shanghai Arch Psychiatry. 2012;24(1):20\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang L, Chen Y, Wang M, Zhao C, Qiao D. Relationship between gene-environment interaction and obsessive-compulsive disorder: A systematic review. J Psychiatr Res. 2023;164:281\u0026ndash;90.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang L, Wang H, Abel GM, Storm DR, Xia Z. The Effects of Gene-Environment Interactions Between Cadmium Exposure and Apolipoprotein E4 on Memory in a Mouse Model of Alzheimer's Disease. Toxicol Sci. 2020;173(1):189\u0026ndash;201.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang X, Gainetdinov RR, Beaulieu JM, Sotnikova TD, Burch LH, Williams RB, Schwartz DA, Krishnan KR, Caron MG. Loss-of-function mutation in tryptophan hydroxylase-2 identified in unipolar major depression. Neuron. 2005;45(1):11\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang Y, Chang Z, Chen J, Ling Y, Liu X, Feng Z, Chen C, Xia M, Zhao X, Ying W, Qing X, Li G, Zhang C. Methylation of the tryptophan hydroxylase\u0026ndash;2 gene is associated with mRNA expression in patients with major depression with suicide attempts. Mol Med Rep. 2015;12(2):3184\u0026ndash;90.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-psychiatry","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bpsy","sideBox":"Learn more about [BMC Psychiatry](http://bmcpsychiatry.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bpsy/default.aspx","title":"BMC Psychiatry","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"TPH2 gene, DNA methylation, Family factors, Obsessive-compulsive disorder","lastPublishedDoi":"10.21203/rs.3.rs-4247451/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4247451/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eObjective:\u003c/strong\u003e The etiology of obsessive-compulsive disorder (OCD) remains incompletely understood. Previous studies have implicated the TPH2 gene and several family factors in OCD. This study aimed to investigate the correlation of TPH2 gene methylation and family factors (parenting styles and family functioning) on OCD and its clinical severity.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethod:\u003c/strong\u003e A total of 88 patients with OCD and 94 healthy controls were enrolled. DNA methylation levels at twelve sites in the promoter region of the TPH2 gene were measured using DNA inflight mass spectrometry system and polymerase chain reaction (PCR). The severity of OCD symptoms was assessed using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). Egna Minnen Barndoms Uppfostran (EMBU) and Family Assessment Device (FAD) scales were used to measure parenting styles and family functioning, respectively.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eDNA methylation levels of CpG site 5 were negatively correlated, and site 6 was positively associated with the onset of OCD. Further analysis revealed a positive association between DNA methylation level at CpG site 5 and a paternal-favoring parenting style as measured by the EMBU in OCD. Additionally, DNA methylation levels at CpG site 2 were positively correlated with maternal emotional warmth of EMBU but negatively correlated with the general functioning of FAD; they were also negatively correlated with compulsive behavior scores and total scores of Y-BOCS. DNA methylation levels at CpG site 1,3,8 were negatively associated with maternal emotional warmth of EMBU while positively correlated with compulsive behavior scores and total scores of Y-BOCS. Moreover, DNA methylation levels of CpG site 9, 10 and 12 were positively associated with problem-solving, total scores of Y-BOCS, and maternal emotional warmth, respectively. Obsessive thoughts were found to be negatively associated only with paternal emotional warmth of EMBU.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion: \u003c/strong\u003eDNA methylation at different CpG sites in the promoter region of the TPH2 gene may play critical roles in the onset and progression of OCD. Parenting styles and family functioning could impact the progression of the disease, and the DNA methylation of the TPH2 gene may mediated the effect of family factors on OCD.\u003c/p\u003e","manuscriptTitle":"Exploring the Influence of DNA Methylation and family factors on OCD and symptoms Severity: Insights into the TPH2 Gene","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-16 09:00:58","doi":"10.21203/rs.3.rs-4247451/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-01-28T14:59:14+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-01-16T17:45:22+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"180587170332839588641944006782516036976","date":"2025-01-10T05:08:27+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-10-11T12:08:13+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"52053604378181167085257273287075575133","date":"2024-09-18T13:06:33+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-09-04T08:36:49+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-07-04T15:37:10+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2024-04-11T18:29:51+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-04-11T18:28:02+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Psychiatry","date":"2024-04-10T12:41:53+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-psychiatry","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bpsy","sideBox":"Learn more about [BMC Psychiatry](http://bmcpsychiatry.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bpsy/default.aspx","title":"BMC Psychiatry","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"3010e523-335d-46c0-9e16-409d956e8816","owner":[],"postedDate":"April 16th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-10-06T16:10:20+00:00","versionOfRecord":{"articleIdentity":"rs-4247451","link":"https://doi.org/10.1186/s12888-025-07217-0","journal":{"identity":"bmc-psychiatry","isVorOnly":false,"title":"BMC Psychiatry"},"publishedOn":"2025-09-30 15:58:12","publishedOnDateReadable":"September 30th, 2025"},"versionCreatedAt":"2024-04-16 09:00:58","video":"","vorDoi":"10.1186/s12888-025-07217-0","vorDoiUrl":"https://doi.org/10.1186/s12888-025-07217-0","workflowStages":[]},"version":"v1","identity":"rs-4247451","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4247451","identity":"rs-4247451","version":["v1"]},"buildId":"zQwnuV7TCBrMSSSToR1PI","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}