{"paper_id":"555d4cd8-0554-4fd5-b677-c9e52c51d955","body_text":"Review\nAn Obstetrics and Gynecology  \nInternational Journal \n115\nvolume 19, issue 3, JulY - sePTemBeR 2020\nStudy of RsaI polymorphism of the ERβ gene  \nin Greek women with endometriosis\nElli Anagnostou, Agathi Theodoropoulou, Despina Mavrogianni, Athanasios Protopapas,  \nPeter Drakakis, Dimitrios Loutradis\n1st Department of Obstetrics and Gynecology, Division of Human Reproduction, IVF Unit, Alexandra Hospital, \nMedical School of National Kapodistrian University of Athens, Athens, Greece\nCorresponding Author\nElli Anagnostou, Division of Human Reproduction, IVF Unit, 1st Department of Obstetrics and Gynecology, Alexandra Hospital, \nAthens University Medical School, Athens, Greece\nTel.: +30 210 3613241, e-mail: elli.anagnostou@gmail.com\nHJoG 2020, 19 (3), 115-122\nAbstract\nEstrogens and estrogen receptors (ERs) play an important role in the pathogenesis of endometriosis. The \naim of this study was to investigate the presence of gene polymorphism RsaI in the gene of the estrogen \nreceptor ERβ in the Greek female population, and its distribution in women suffering from endometriosis \nand in a control group. We included 67 consecutive infertile women of Caucasian origin who were operated \nlaparoscopically in our Gynecological Endoscopy Unit for endometriosis, and 96 women participated as \ncontrol group. Patients were genotyped for RsaI (G/A, rs1256049) polymorphism in ESR2 exon 5, using \nreal-time PCR. The patients’ genotype distribution did not differ from the control group. There were no \nwomen homozygous for the polymorphic allele in neither group. The different genotypes of ESR2 could \nnot be associated with the stage of endometriosis . The data of this study point that in Greek population \nwho had proven endometriosis the determination of RsaI polymorphism of ESR2 gene doesn’t offer any \ninformation for the progression of endometriosis, regarding the genetic profile of this particular gene.\nKey words: ERβ, SNP , gene polymorphism, endometriosis \nIntroduction\nEndometriosis is an estrogen dependent inflamma-\ntory condition in which the endometrium develops \nin a region outside the uterus, as in the organs of \nthe abdomen and pelvis, such as the ovaries, peri -\ntoneum or vagina, or rarely in distant organs such \nas the lungs\n1.\nEstrogens and estrogen receptors (ERs) play an \nimportant role in the pathogenesis of endometriosis. \nEstradiol is involved in the growth, differentiation \nand function of reproductive tissues, while endo-\nmetriosis is an estrogen-dependent disease. Genetic \nabnormalities and environmental factors including di-\netary, hormonal and non-hormonal conditions could \ncontribute to the development of endometriosis2.\n\n116\nAnagnostou et al\nvolume 19, issue 3, JulY - sePTemBeR 2020\nThe pathogenesis of endometriosis is not known. \nThere are several theories that interpret it partially \nbut not completely. Many studies have shown that in \nsome women there is a predisposing hereditary fac-\ntor, which in combination with other immunological \nand biochemical factors results in the formation of \nendometrial foci outside the uterus3. Environmental \nparameters also seem to enhance the development \nof endometriosis. The most well-known theory of \nendometriosis development is through the migration \nof endometrial cells during menstruation, through \nthe fallopian tubes, into the abdomen.\nThe clinical picture depends on the location and \nextent of the lesions, although the severity of the symp-\ntoms is not necessarily compatible with the spread and \nseverity of the condition. Endometriosis can result to \nthe impairment of the woman’s reproductive function. \nOne in three women with infertility problems has \nendometriosis. It has been observed that women with \nendometriosis have difficulty in conceiving4.\nGenetic polymorphism is defined as the occurrence \nof multiple alleles in a genetic locus, where at least \ntwo alleles occur with a frequency greater than 1% \nof the population. A polymorphic genetic site can \nbe found anywhere in the genome and not neces-\nsarily in a gene. The importance of polymorphisms \nlies in the fact that in many cases these variants \nmodify the structure or function or expression of \na protein, and this can have consequences for the \nfunction of enzymes, carriers, receptors or other \npossible target molecules involved in mediation of \nthe action of drugs. This, in turn, explains in part \nthe observed - among individuals - differences in \nclinical phenotypes and pharmacological responses5.\nEstrogens mediate their actions through two sub-\ntypes of nuclear receptors, ERa and ERb, which are \nencoded by ESR1 and ESR2 genes, present on distinct \nchromosomes (locus 6q25.1 and locus 14q23-24.1, \nrespectively). Both forms of the receptor have been \nidentified in the human ovary6.\nERa and ESR1 gene\nESR1 gene contains some well-studied single nu-\ncleotide polymorphisms (SNPs).  The most widely-\nstudied polymorphisms of restriction fragments length \n(RFLPs) are PvuII (T397C) and Xbal (A351G) in intron \nI, and the (TA) variable number of tandem repeat \n(VNTR) region within the promoter of the genomic \noxide. In various studies, these polymorphisms have \nbeen associated with a number of pathological condi-\ntions: breast cancer and prostate cancer, osteoporosis, \nAlzheimer’s disease, and cardiovascular disease.\nGeorgiou et al in 1999 investigated in the Greek \npopulation the relationship between the PvuII \npolymorphism and the (TA) variable number of \nthe estrogen receptor with endometriosis 7. There \nwas a statistically significant difference between \nthe patients and the controls in the frequency of \nthe two-allele Pvu II polymorphism (0.72 vs. 0.49) \nand in the median repeats of the (TA)n multiallele \npolymorphism (15 vs. 20 repeats). In both groups, \nlinkage was found between the fewer (TA)n repeats \n(range, 12–19) and the positive Pvu II polymorphism. \nThe study concluded that the gene diversity of the \nestrogen receptor (ER) is likely to contribute to the \npathogenesis of endometriosis.\nHsieh et al in 2007 observed that the distributions \nof frequencies of the genotypes Xba I A/G and PvuII \nT/C of ERa was significantly different between in-\ndividuals with and without endometriosis8. Specific \nallele variants for the ERa correlated with more \nsevere endometriosis: XbaI GG genotype is associ -\nated with moderate association with endometriosis.\nThe role of PvuII polymorphism of the ESR1 gene \nreportedly correlates with the severity of endometrio-\nsis7-8 as well as with the ovarian stimulation during \nIVF9 and the outcome of the pregnancy after IVF 10. \nMorever, the repeat polymorphisms dinucleotide \n(TA) of the promoter of the ESR1 gene has been \nproposed to increase the risk of premature ovarian \nfailure\n11 and of endometriosis7.\n\n117\nStudy of RsaI polymorphism of the ERβ gene in Greek women with endometriosis\nvolume 19, issue 3, JulY - sePTemBeR 2020\nA recently conducted study included twenty con-\nsecutive infertile Greek women who were operated \nlaparoscopically in our Gynecological Endoscopy \nUnit for advanced endometriosis and 48 parous \nwomen as controls, with a history of at least one \nsuccessful pregnancy, no history of spontaneous \nabortion, and no known history of endometriosis \n(unpublished data). Real time PCR was applied in \nall samples to detect the distribution of the PvuII \npolymorphism of ERa.  The presence of the PvuII \npolymorphism in both alleles (CC genotype) was \nfound in only 6.7% of patients with endometriosis, \ncompared with 35.4% of controls (p=0.033). In this \nstudy the ESR1 polymorphism was found less com-\nmonly in a homozygous condition in patients with \nendometriosis in comparison with controls, a finding \nwhich is not of accordance with previous studies that \nhave demonstrated a positive correlation between \nendometriosis and ESR1 polymorphisms12-13, whereas \nothers reported no significant association14.\nERb and ESR2 gene\nThe ESR2 gene coding for ERβ has been mapped \nand is located on the long arm of chromosome 14. \nThe first studies that were performed on this gene \nconcerned the highly polymorphic recurrent di-\nnucleotide in exon 5 in a Japanese population 15. \nPolymorphisms involve the simultaneous appearance \nof a population of two or more alternative genotypes, \neach of which has a higher frequency than it could be \njustified by repeated mutations alone. Five different \nsequences of variations, including two mutations and \nthree polymorphisms, were detected. More recently, \nfive new polymorphisms have been identified in the \nAfrican population. Three of them (C143T on exon 1, \nA566T on exon 2 and T1100G on exon 5) are silent \npolymorphisms, while the other two changed the \nsequence of ERβ amino acids.\nHapangama et al support that endometriosis is \nassociated with decreased ERβ endometrial ex -\npression and is associated with cell proliferation \nand ascending telomerase regulation 16. Silva et al \nexplored whether estrogen receptors are associ-\nated with endometriosis and whether they could \noffer a genetic explanation of the disease etiology, \ncontributing to its diagnosis and treatment 17. For \nthis purpose, the frequency of RsaI polymorphism of \nthe ERβ gene in patients with endometriosis and in \nasymptomatic patients was examined. The genotypic \nfrequencies found in patients with endometriosis \n(N = 54) were: 0% with AA gene genotype, 59.3% \nwith AG genotype and 40.7% with GG genotype. \nAmong the control group of patients (N = 46) the \nfrequencies were 0% with AA gene genotype, 6.5 \n% with AG genotype and 93.5% with GG genotype. \nThe frequency of the heterozygous AG genotype of \nRsaI polymorphism in patients with endometriosis \nwas about nine times higher than in patients in the \ncontrol group (P <0.001).\nSundarrajan et al suggested that the RsaI (G/A) \nlocus in the ESR2 gene is associated with ovarian \nfailure of unknown cause18. Others studies did not \nfind any effect of the polymorphism RsaI G/A and \nAluI G/A of the ESR2 gene on the COS outcome\n19-20. \nThe results suggest that these polymorphisms may \nbe associated with ovulatory abnormalities in some \npatients, especially in couples with unknown causes \nof infertility. \nThe aim of this study was to investigate the pres-\nence of gene polymorphism RsaI in the gene of the \nestrogen receptor ERβ in the Greek female popula-\ntion, and its distribution in women suffering from \nendometriosis and in a control group. The presence \nof RsaI gene polymorphism was also evaluated re-\ngarding the stage of endometriosis, the age of the \ndiagnosis, menarche, and the pregnancy outcome \nas well.\nMaterials and Methods\nThis study was conducted in the 1st Department \n\n118\nAnagnostou et al\nvolume 19, issue 3, JulY - sePTemBeR 2020\nof Obstetrics and Gynecology of the National and \nKapodistrian Univesity of Athens, Greece. We in-\ncluded 67 consecutive infertile women of Caucasian \norigin who were operated laparoscopically in our \nGynecological Endoscopy Unit for endometriosis. \nIn all cases disease was confirmed histologically. \nWritten informed consent was read and signed by \nall participants. The study has been approved by the \nReview Board of our Institution. As control group, 96 \nwomen participated: they were all parous women \nwith a history of at least one successful pregnancy, \nno history of spontaneous abortion, and no known \nhistory of endometriosis.\nMolecular analysis \nPeripheral blood was collected from all women, \nin both groups. Genomic DNA was obtained from \nperipheral blood leucocytes with the QIAamp DNA \nBlood Kit (QIAGEN, Hilden, Germany) according to \nthe manufacturer’s instructions. Patients were geno-\ntyped for RsaI (G/A, rs1256049) polymorphism in \nESR2 exon 5, using real-time PCR (Light Cycler 480 \nII, Roche Diagnostics, Germany). The conditions of \nthe real-time PCR for the ESR2 RsaI polymorphism \nare described elsewhere\n21.\nStatistical Analysis\nStatistical analysis was performed with Statis-\ntics Package for Social Sciences (SPSS), version 15, \nMinitab 12, while the Sasieni algorithm (1997) and \nHardy-Weinberg equilibrium were performed with \nthe on line calculator which is available on http://ihg.\ngsf.de. The statistical methods used for the control of \nstatistical hypothesis were: two independent samples \nt-test, 2-proportion test (normal approximation) \nand parametric one way Analysis of Variance. For \nqualitative data used the chisquare test (Fisher exact \ntest and Monte Carlo procedure). The non parametric \ntests Mann-Whitney U and Kruskal-Wallis test were \nused when needed.\nA P-value less than 0.05 were regarded as statisti-\ncally significant. Values are presented as mean±SD, \nunless otherwise stated.\nResults \nThis study included 67 women with endometriosis \nand 96 women as controls. \nIn all cases, ESR2 genotyping was performed and \nthe women in both groups were categorized as ho-\nmozygous for the wild type WT allele (GG genotype), \nheterozygous (GA genotype), and homozygous for \nthe polymorphic allele (AA genotype), according to \nPCR results.\nThe distribution of women according to the geno-\ntype for RsaI gene polymorphism is shown in Table \n1. In the control group, 91/96 (94.8%) women were \nhomozygous for the wild type (GG), 5/96 (5.2%) \nwere heterozygous (GA) and no woman (0%) was \nhomozygous for the polymorphism (AA). In the en-\ndometriosis group, 65/67 (97%) were homozygous \nfor the wild type and 2/67 (3.0%) were heterozy -\ngous, and no woman (0%) was homozygous for the \npolymorphism respectively. The patients’ genotype \ndistribution did not differ from the control group \n(p-value 0.490).\nFurther on, the different genotypes of ESR2 are \nassociated with the stage of endometriosis, which \nreflects the severity of the disease (Table 2). The \npresence of wild type genotype in stages I, II was \n27.1%, in stage III 44.1% and in stage IV 28.8%. \nTable 1. Genotype distribution of RsaI ESR2 \ngene polymorphism in the control group and the \nendometriosis group of women (p-value 0.490).\nGenotypes  \nof RsaI snp\nesR2 Gene\nContR ol  \nGRoup\n(n=96)\nendometIosIs \nGRoup\n(n=67)\nGG 91 (94.8%) 65 (5.2%)\nGA 5 (97%) 2 (3%)\nAA 0 (0%) 0 (0%)\n\n119\nStudy of RsaI polymorphism of the ERβ gene in Greek women with endometriosis\nvolume 19, issue 3, JulY - sePTemBeR 2020\nConcerning the heterozygous for the polymorphism \npatients (n=2), one patient presented stage III en-\ndometriosis and the other stage IV endometriosis \n(p value = 1.0).\nAll parameters regarding the age at the diagnosis \nof endometriosis, menarche, pregnancies and de-\nliveries, were not statistically different, except the \nage of the diagnosis of the endometriosis. Of course, \nthe statistical analysis is weak, because in the study \npopulation the prevalence of the homozygous for the \npolymorphism genotype of ESR2 is 0% and concern-\ning the heterozygous it ranged between 3-5.2%, in \nboth groups. Taking into account that this gene is \nvery rare in Greek population, it is difficult to draw \ndistinct conclusions regarding the significance of \nthis genotype and the relation with endometriosis \nin Greek population.\nDiscussion \nIn this study we examined the association of RsaI \nESR2 polymorphism in endometriosis, and the impact \nof this genotype in the features of endometriosis in \nGreek population. \nIt is already know from several studies in different \nethnicities that the estrogen receptors are associated \nwith endometriosis and there is a genetic etiology, \nwhich may contribute to its diagnosis and treatment \nregarding this disease.\nSilva et al examined the estrogen receptors in as-\nsociation with endometriosis in order to highlight \na genetic connection\n17. The frequency of RsaI poly-\nmorphism of the ERβ in patients with endometriosis \nand in asymptomatic patients was examined. The \ngenotype distribution found in patients with endo-\nmetriosis (N = 54) was 0% for AA gene genotype, \n59.3% for AG genotype and 40.7% for GG genotype. \nAmong the control group patients (N = 46) the dis-\ntribution was 0% for AA gene genotype, 6.5 % for AG \ngenotype and 93.5% for GG genotype. The incidence \nof heterozygous genotypes AG of RsaI polymorphism \nof the ER β gene in patients with endometriosis was \nabout nine times higher than in patients in the con-\ntrol group (P <0.001).  Our data did not reveal any \ndifference in the genotype distribution profile in the \nendometriosis group and the control group in Greek \npopulation. More specifically, the wild type distribu-\ntion was >90% in both endometriosis and control \ngroup. Thus, our results suggest that the RsaI gene \npolymorphism is not associated with endometriosis \nand that there is no over-presentation of a certain \ngenotype in endometriosis in the Greek population. \nThis design of this study did not permit to drawn any \nother conclusion, because 97% of both populations \ncarried the wild type genotype (GG). \nThe positive correlation between endometriosis \nand ESR1 polymorphisms is well known. The study \nof Hsieh et al (2007) observed that the distributions \nof frequencies of the genotypes XbaI A/G and PvuII \nT/C of ERa were significantly different between \nindividuals with and without endometriosis8, while \na recent study in a Greek population (unpublished \ndata) did not associate the presence of the PvuII \npolymorphism of ESR1 gene in patients with endo-\nmetriosis, compared to controls.  \nTo date, the studies in Greek population regard-\ning the ESR1 gene imply that it is related to endo -\nmetriosis, while ESR2 gene polymorphism doesn’t \nseem to be implicated with the presence of endo-\nmetriosis and this polymorphism in particular is \npoorly represented. This result is also confirmed by \nthe study of Georgiou et al, which showed that ERb \nTable 2. Genotype association of RsaI ESR2 gene \npolymorphism with the stage of endometriosis \n(p value = 1.0).\nGenotypes \nof RsaI\nesR2 Gene\nSt age I-II\n(n=16)\nst a Ge III\n(n=27)\nst a Ge IV\n(n=18)\nGG 16 26 17\nGA 0 1 1\n\n120\nAnagnostou et al\nvolume 19, issue 3, JulY - sePTemBeR 2020\npolymorphisms are rare in Greek patients enrolled \nin an IVF attempt9.\nIn this study we also examined the association of \nthe genotypes of ESR2 with the stage of endome-\ntriosis, which reflects the severity of the disease. \nThe presence of wild type genotype in stages I, II \nwas 27.1%, in stage III 44.1% and in stage IV 28.8%. \nConcerning the heterozygous for the polymorphism \npatients (n=2), one patient presented stage III en-\ndometriosis and the other stage IV endometriosis. \nThus, these data do not allow us to draw conclusions \nabout the implication of RsaI SNP in the severity of \nendometriosis.  It would be of interest to see if the \npopulations that express in greater percentage the \npolymorphism, whether it is associated with severe \nendometriosis.\nFurthermore, our data regarding the age at the \ndiagnosis of endometriosis, menarche, pregnancies \nand deliveries, were not statistically different, except \nthe age of the diagnosis of the endometriosis.\nMany epidemiological studies have suggested an \nassociation between estrogen receptor-beta (ER-β) \npolymorphisms with endometriosis risk. However, \nthe results of these studies have been inconsistent. \nThe meta-analysis that conducted Guo in 2014 sug-\ngested that the ER-β rs4986938 and rs1256049 poly-\nmorphisms are not associated with endometriosis \nrisk in overall population, a result which was consis-\ntent with the results of a previous meta-analysis22.\nIf we consider the contemporary meta-analysis in \nthis field, there is insufficient evidence for implication \nof the ER-β polymorphism in the etiology of endome-\ntriosis- associated infertility for population testing. \nThe observed increase in risk of endometriosis-\nassociated infertility may be due to bias because of \nthe inclusion of small-scale studies. It is critical that \nlarger and well-designed multicenter studies should \nbe performed to re-evaluate potential associations.\nFinally, an Italian study conducted by Pagliardini, \nconfirmed that the polymorphisms of the Wnt4, CD-\nKN2BAS and FN1 genes as genetic sites involved in \nendometriosis pathology23. Also, another study con-\nducted in Brazilian population by Barbosa, showed \nthat the combined examination of the genotypes of \nthe FCRL3 and FOXP3 polymorphisms present an  \ninteraction of the FOXP3CT / FCRL3-TT or TC or \nCC genotypes with an accumulated  profile which \ndrive to the evolutionary effect  of endometriosis24.\nConclusion\nIn conclusion, the data of this study point that in \nGreek population who had proven endometriosis the \ndetermination of RsaI polymorphism of ESR2 gene \ndoesn’t offer any information for the progression of \nendometriosis, regarding the genetic profile of this \nparticular gene.\nOverall, the impact of endometriosis and its stag-\ning on assisted reproduction outcome is quite im-\nportant, as recent meta-analysis underlines\n25, thus \nstudies with larger populations would be of greater \nvalue, in order to define the genetic mechanisms  \nbehind the disease and the role of the specific gene \npolymorphisms that are involved in the pathology \nof endometriosis.\nReferences\n1. Burney RO, Giudice LC: Pathogenesis and patho-\nphysiology of endometriosis. Fertil Steril 2012;98: \n511-519,.\n2. Sano M, Morishita T , Nozaki M, Yokoyama M, Wata-\nnabe Y, Nakano H : Elevation of the Phospholipase \nA2 Activity in Peritoneal Fluid Cells From Women \nWith Endometriosis. Fertil Steril 1994;61:657-62.\n3. Stefansson H, Geirsson RT , Steinthorsdottir V, Jons-\nson H, Manolescu A, Kong A, Ingadottir G, Gulcher \nJ, Stefansson K: Genetic factors contribute to the \nrisk of developing endometriosis. Hum Reprod \n2002;17: 555-9.\n4. Somigliana E, Vigano P , Benaglia L, Busnelli A, Ber-\nlanda N, Vercellini P : Management of Endometri-\n\n121\nStudy of RsaI polymorphism of the ERβ gene in Greek women with endometriosis\nvolume 19, issue 3, JulY - sePTemBeR 2020\nosis in the Infertile Patient. Semin Reprod Med \n35(1):31-37, 2017.\n5. Flordellis C, Paris H, Karabinis A, Lymperopoulos \nA :Pharmacogenomics of adrenoceptors. Pharma-\ncogenomics 2004;5:803-17.\n6. Jia M, Dahlman-Wright K, Gustafsson JÅ: Estro-\ngen receptor alpha and beta in health and disease. \nBest Pract Res Clin Endocrinol Metab 29(4):557-\n68, 2015.\n7. Georgiou I, Syrrou M, Bouba I, Dalkalitsis N, Pas-\nchopoulos M, Navrozoglou I, Lolis D: Association \nof estrogen receptor gene polymorphisms with \nendometriosis. Fertil Steril 1999;72:164-6.\n8. Hsieh YY, Wang YK, Chang CC, Lin CS: Estrogen re-\nceptor alpha-351 XbaI*G and -397 PvuII*C-related \ngenotypes and alleles are associated with higher \nsusceptibilities of endometriosis and leiomyoma. \nMol Hum Reprod 2007;13:117-22.\n9. Georgiou I, Konstantelli M, Syrrou M, Messinis IE, \nLolis DE : Oestrogen receptor gene polymorphisms \nand ovarian stimulation for in-vitro fertilization. \nHum Reprod, 1997;12:1430-3.\n10. Sundarrajan C, Liao WX, Roy AC, Ng SC: Associa-\ntion of oestrogen receptor gene polymorphisms \nwith outcome of ovarian stimulation in patients \nundergoing IVF. Mol Hum Reprod 1999;5, 797-802.\n11. Syrrou M, Georgiou I, Patsalis PC, Bouba I, Adona-\nkis G, Pagoulatos GN: Fragile X Premutations and \n(TA)n Estrogen Receptor Polymorphism in Wom-\nen With Ovarian Dysfunction. Am J Med Genet \n1999;84:306-8.\n12. Lamp M, Peters M, Reinmaa E, Haller-Kikkatalo K, \nKaart T , Kadastik U, Karro H, Metspalu A, Salumets \nA: Polymorphisms in ESR1, ESR2 and HSD17B1 \ngenes are associated with fertility status in endo-\nmetriosis. Gynecol Endocrinol 2011;27:425-33.\n13. Wang W, Li Y, Maitituoheti M, Yang R, Wu Z, Wang \nT , Ma D, Wang S : Association of an oestrogen re-\nceptor gene polymorphism in Chinese Han wom-\nen with endometriosis and endometriosis-related \ninfertility. Reprod Biomed Online 2013;26:93-8.\n14. Wang Z, Yoshida S, Negoro K, Kennedy S, Barlow D, \nMaruo T: Polymorphisms in the estrogen receptor \nbeta gene but not estrogen receptor alpha gene af-\nfect the risk of developing endometriosis in a Jap-\nanese population. Fertil Steril 2004;81:1650-6.\n15. Tsukamoto K, Inoue S, Hosoi T , Orimo H, Emi M: \nIsolation and radiation hybrid mapping of dinucle-\notide repeat polymorphism at the human estrogen \nreceptor beta locus. J Hum Genet 1998;43:73-4.\n16. Hapangama DK, Turner MA, Drury JA, Martin-Ruiz \nC, Von Zglinicki T , Farquharson RG, Quenby S: En-\ndometrial telomerase shows specific expression \npatterns in different types of reproductive failure. \nReprod Biomed Online 2008;17:416-24.\n17. Silva RCPC, Costa IR, Bordin BM, Silva CTX, Sou-\nza SR, Júnior CLR, Frare AB,  Moura KKVO: RsaI \nPolymorphism of the ERβ Gene in Women With \nEndometriosis. Genet Mol Res 2011; 10:465-70.\n18. Sundarrajan C, Liao WX, Roy AC, Ng SC: Associa-\ntion between estrogen receptor-beta gene poly -\nmorphisms and ovulatory dysfunctions in patients \nwith menstrual disorders. J Clin Endocrinol Metab \n2001;86:135-9.\n19. Altmäe S, Haller K, Peters M, Hovatta O, Stavreus-\nEvers A, Karro H, Metspalu A, Salumets A: Allel-\nic estrogen receptor 1 (ESR1) gene variants pre-\ndict the outcome of ovarian stimulation in in vitro \nfertilization. Mol Hum Reprod 2007;13, 521-6.\n20. de Castro F, Moron FJ, Montoro L, Galan JJ, Her-\nnandez DP , Padilla ES, Ramirez-Lorca R, Real LM, \nRuiz A: Human controlled ovarian hyperstimula-\ntion outcome is a polygenic trait. Pharmacogenet-\nics 2004;14, 285-93.\n21. Anagnostou E, Mavrogianni D, Theofanakis Ch, \nDrakakis P , Bletsa R,  Demirol A, Gurgan T , Antsak-\nlis A, Loutradis D: ESR1, ESR2 and FSH Receptor \nGene Polymorphisms in Combination: A Useful Ge-\nnetic Tool for the Prediction of Poor Responders. \nCurr Pharm Biotechnol 2012;13:426–34.\n\n122\nAnagnostou et al\nvolume 19, issue 3, JulY - sePTemBeR 2020\n22. Guo R, Zheng N, Ding S, Zheng Y, Feng L: Associa-\ntions between estrogen receptor-beta polymor -\nphisms and endometriosis risk: a meta-analysis. \nDiagn Pathol 2014;26;9:184.\n23. Pagliardini L, Gentilini D, Vigano’ P , Panina-Bordi-\ngnon P , Busacca M, Candiani M, Di Blasio AM: An \nItalian association study and meta-analysis with \nprevious GWAS confirm WNT4, CDKN2BAS and \nFN1 as the first identified susceptibility loci for \nendometriosis. J Med Genet 2013;50:43-6.\n24. Barbosa CP , Teles JS, Lerner TG, Peluso C, Mafra \nFA, Vilarino FL, Christofolini DM, Bianco B: Genet-\nic association study of polymorphisms FOXP3 and \nFCRL3 in women with endometriosis. Fertil Ster-\nil 2012;97:1124-8.\n25. Barbosa MA, Teixeira DM, Navarro PA, Ferriani RA, \nNastri CO, Martins WP: Impact of endometriosis \nand its staging on assisted reproduction outcome: \nsystematic review and meta-analysis. Ultrasound \nObstet Gynecol 2014;44:261-78.\nReceived 30-04-20\nRevised 14-05-20\nAccepted 19-05-20","source_license":"CC0","license_restricted":false}