Prenatal diagnosis of a fetus with trisomy 9 mosaicism

Prenatal diagnosis of a fetus with trisomy 9 mosaicism | 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 Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Case Report Prenatal diagnosis of a fetus with trisomy 9 mosaicism Xiao-Min Zhang, Yi-Qiong Yang, Yu-Ling Wang, Chen Ling, Li Liang, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6100761/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Trisomy 9 is a rare chromosomal disorder[1, 2]. Complete trisomy 9 is often fatal, and chromosome 9 mosaicism is commonly observed in clinical practice. Patients with this mosaicism mainly present with "ball nose", microphthalmia, limb dislocation, and other skeletal, cardiac, urogenital and central nervous system malformations.[3]. Case presentation Chromosomal karyotype analysis, chromosomal microarray analysis and fluorescence in situ hybridization analysis were used for the diagnosis of a case of trisomy 9 mosaicism, and a variety of genetic testing techniques were further used for detailed analysis. Conclusion We report a rare case of trisomy 9 mosaicism; fewer than five comparable cases have been reported in the literature. This case highlights the importance of genetic counseling and appropriate genetic testing for prenatal diagnosis. Trisomy 9 Mosaicism Prenatal diagnosis Figures Figure 1 Figure 2 Background Trisomy 9 is a rare chromosomal disorder with high neonatal mortality[ 4 – 6 ]. It is generally observed in the mosaic state. The proportion of cells with trisomy 9 in different tissues is closely related to the incidence and severity of malformations and the degree of intellectual disability. In genetic counseling for mosaicism, a variety of influencing factors should be comprehensively considered, including the chromosome position, mosaicism proportion, distribution of fetal abnormal cell lines, detection method and culture method[ 7 – 9 ]. The manifestations of trisomy 9 mosaicism are diverse, the phenotype can range from no obvious abnormality to a typical phenotype, and the clinical phenotype and severity may vary with the proportion of abnormal cells. The degree of clinical variation caused by mosaicism is related to the location of the tissues with mosaicism [ 10 – 12 ]. Therefore, in the prenatal diagnosis of trisomy 9 mosaicism, genetic counseling for three-body chimeras is difficult; in this study, a variety of genetic methods were used to analyze cases of trisomy 9 mosaicism in fetuses[ 13 – 15 ]. Case presentation We report the case of a 32-year-old, 20-week pregnant woman with no family history of genetic disorders or consanguineous marriage. Because Down syndrome screening indicated a high risk of Edward syndrome (trisomy 18) (ED 1/5), noninvasive prenatal testing (NIPT) was conducted at 17 gestational weeks and suggested a high risk of trisomy 9. Ultrasound suggested that the femur and humerus were less than 2 SDs for the gestational age standard. After genetic counseling was provided and informed consent was obtained, amniocentesis was recommended for prenatal diagnosis. The results of the G-banding karyotype analysis revealed 47,XX, + 9 [ 19 ]/46, XX[56], which indicated trisomy 9 with a mosaicism rate of 25.3% (Fig. 1). The results of the G-banding karyotype analysis of the peripheral blood of the woman and her husband revealed no obvious abnormalities. Subsequent single nucleotide polymorphism (SNP) array analysis (HumanCytoSNP-12v2.1, Illumina) revealed arr [hg19] 9p24.3q34.3 (208455-141018648) X 2–3 (Fig. 2), which indicated trisomy 9, with a mosaicism ratio of 28%. Single nucleotide polymorphism (SNP) array analysis (HumanCytoSNP-12v2.1, Illumina) revealed arr [hg19] 9p24.3q34.3 (208455-141018648) X 2–3 (Fig. 2) and a trisomy 9 mosaicism rate of 28%. To further verify the SNP array results, fluorescence in situ hybridization (FISH) analysis was performed with a CEP9 probe and revealed nuc ish(D9Z1)×3[ 9 ]/(D9Z1)×2[91], and approximately 9% of the cells showed trisomy 9. According to the test results, the pregnant woman was informed of the potential risks after receiving detailed genetic counseling. The pregnant woman and her family members were willing to terminate the pregnancy, and there was no obvious abnormality in the appearance of the fetus after induced labor. Discussion and conclusion NIPT-cell-free fetal DNA from maternal serum samples, mainly from placental trophoblasts, is not obtained directly from fetuses[ 3 ]; therefore, for NIPT-detected chromosomal aneuploidy, prenatal diagnosis is strongly recommended for pregnant women[ 16 , 17 ]. The mechanism of chromosomal mosaicism is complex. During meiosis of germ cells, the chromosomes of the primary oocyte do not disassociate and develop monosomy or three cells. Abnormal mitosis in early embryos can also lead to chromosomal mosaicism, but the specific molecular mechanism of mosaicism is poorly understood [ 18 , 19 ]. Trisomy 9 is a common autosomal trisomy leading to miscarriage in early pregnancy [ 16 ] and usually leads to spontaneous embryo abortion, intrauterine growth restriction, and multiple congenital abnormalities [ 20 ]. Most fetuses with developmental disorders associated with complete trisomy 9 are lost in the early stage, and most survivors are chimeras. The clinical manifestations of trisomy 9 mosaicism are diverse and involve multiple organ system abnormalities, including craniofacial abnormalities (micropalpebral cleft, large nasal bridge, dental abnormalities, low-set ears and micrognathia, etc.), skeletal abnormalities (joint contractures, dislocations, and acrogenetic abnormalities), and cardiac abnormalities (atrioventricular septal defects are common). "Developmental abnormalities of the urogenital system (cryptorchidism) and the central nervous system (epilepsy) [ 21 ]. In the prenatal diagnosis of this fetus, NIPT, amniotic fluid cell karyotype analysis, CMA, and FISH all detected trisomy 9 mosaicism, but the proportions of mosaicism were inconsistent. In prenatal diagnosis, it is regularly recommended that at least two detection techniques to detect chimerism be used to establish a diagnosis of plastic chimerism [ 22 , 23 ]. Therefore, in clinical practice, when mosaicism is suggested in karyotype analysis, SNP array should be used as a first-line diagnostic technique for prenatal diagnosis, or FISH should be combined with cytogenetic technology to analyze uncultured cells to further confirm the diagnosis and determine the proportion of cells with mosaicism[ 24 ]. Karyotype analysis of amniotic fluid cells and CMA tests of uncultured amniotic fluid cells both suggested the presence of trisomy 9 mosaicism, and the mosaicism rates were 25.3% and 28%, respectively. In the fetal ultrasound examination, the lengths of the femur and humerus of the fetus were − 2 SDs below the corresponding gestational age standard, which did not exclude the possibility of growth restriction and skeletal dysplasia, and no other abnormal phenotypes were found[ 25 , 26 ]. Many researchers have revealed that the correlation analysis between the chimerism ratio and prenatal ultrasound results revealed that there was no clear correlation between the chimerism ratio and fetal ultrasound examination results, and it was not possible to predict the severity of the fetal phenotype and prognosis on the basis of the chimerism ratio. Therefore, it is very difficult to evaluate the possible phenotype of trisomy 9 mosaicism in prenatal diagnosis, which also means that genetic counseling is also challenging. In the process of counseling, it is necessary to comprehensively consider many factors, including the chromosome involved, the proportion of cells with mosaicism, and whether there is a relevant phenotype shown on ultrasound examination[ 27 , 28 ]. In conclusion, the diagnosis of chimerism requires the combination of multiple detection techniques. Trisomy 9 mosaicism has limited intrauterine manifestations and significant individual differences and causes multiple system abnormalities, which present great challenges for clinical prenatal diagnosis and genetic counseling for fetuses with trisomy 9 mosaicism. Therefore, combining multiple effective detection methods, case collection, and long-term prenatal and postnatal monitoring are beneficial for the future prenatal diagnosis and genetic counseling for trisomy 9 mosaicism. Declarations Ethics approval and consent to participate This study involves human participants but the Ethics Committee of the Women and Children Healthcare Hospital of Zhuzhou exempted this study. Participants gave informed consent to participate in the study before taking part. Patient consent for publication Consent obtained directly from patient(s). Competing interests The authors declare that they have no competing interests. Author details Women and Children Healthcare Hospital of Zhuzhou, No. 128 Che Zhan Road, Zhuzhou 412000, Hunan Province, China. Received: 18 November 2022 Funding Program : Natural Science Foundation of Hunan Province ( 2024JJ7648); Zhuzhou Entrepreneurship and Innovation Elite Talent Project (2023)29 Author Contribution Xiao-Min Zhang, and Yi-Qiong Yang carried out the clinical evaluation and collected the clinical data from the family. Liu Ni and Hongping Huang conducted the genetic counseling. Yu-Ling Wang, Chen Ling, Li Liang, Wenying Li, Sainan Tan performed the genetic testing and interpretation of the results, Hunjin Luo drafted the manuscript. All authors read and revised the manuscript. Acknowledgments We thank the family for their participation in this study. Data availability The raw data supporting the conclusions of this article will be made available by the authors on request. References E.S. Cantu, D.J. Eicher, G.S. Pai, C.J. Donahue, R.A. Harley, Mosaic vs. nonmosaic trisomy 9: report of a liveborn infant evaluated by fluorescence in situ hybridization and review of the literature, Am J Med Genet 62(4) (1996) 330-5. G. Anneren, G. Sedin, Case report. Trisomy 9 syndrome, Acta Paediatr Scand 70(1) (1981) 125-8. F. Stipoljev, M. Kos, M. Kos, B. Miskovi, R. Matijevic, T. Hafner, A. Kurjak, Antenatal detection of mosaic trisomy 9 by ultrasound: a case report and literature review, J Matern Fetal Neonatal Med 14(1) (2003) 65-9. J.C. Ferreres, S. Planas, E.A. Martinez-Saez, T. Vendrell, V. Peg, M.T. Salcedo, Y.C.S. Ramon, N. Toran, Pathological findings in the complete trisomy 9 syndrome: three case reports and review of the literature, Pediatr Dev Pathol 11(1) (2008) 23-9. B.R. Benacerraf, S. Pauker, B.J. Quade, F.R. Bieber, Prenatal sonography in trisomy 9, Prenat Diagn 12(3) (1992) 175-81. B.F. Carpenter, D.J. Tomkins, The trisomy 9-syndrome, Perspect Pediatr Pathol 7 (1982) 109-20. O. Kor-Anantakul, C. Suwanrath, S. Kanngurn, S. Rujirabanjerd, T. Suntharasaj, S. Pinjaroen, Prenatal diagnosis of complete trisomy 9: a case report and review of the literature, Am J Perinatol 23(2) (2006) 131-5. M. Li, J. Glass, X. Du, H. Dubbs, M.H. Harr, M. Falk, T. Smolarek, R.J. Hopkin, E. Zackai, S.E. Sheppard, Trisomy 9 mosaic syndrome: Sixteen additional patients with new and/or less commonly reported features, literature review, and suggested clinical guidelines, Am J Med Genet A 185(8) (2021) 2374-2383. C.P. Chen, S.R. Chern, S.J. Cheng, T.Y. Chang, L.F. Yeh, C.C. Lee, C.W. Pan, W. Wang, C.Y. Tzen, Second-trimester diagnosis of complete trisomy 9 associated with abnormal maternal serum screen results, open sacral spina bifida and congenital diaphragmatic hernia, and review of the literature, Prenat Diagn 24(6) (2004) 455-62. X. Liu, S. Liu, H. Wang, T. Hu, Potentials and challenges of chromosomal microarray analysis in prenatal diagnosis, Front Genet 13 (2022) 938183. J. Ma, D.S. Cram, J. Zhang, L. Shang, H. Yang, H. Pan, Birth of a child with trisomy 9 mosaicism syndrome associated with paternal isodisomy 9: case of a positive noninvasive prenatal test result unconfirmed by invasive prenatal diagnosis, Mol Cytogenet 8 (2015) 44. C.P. Chen, T.M. Ko, S.W. Chen, S.R. Chern, F.T. Wu, Y.T. Pan, C.W. Pan, Y.Y. Chen, W. Wang, Low-level mosaic trisomy 9 at amniocentesis associated with a positive non-invasive prenatal testing for trisomy 9, maternal uniparental disomy 9, intrauterine growth restriction and a favorable fetal outcome in a pregnancy, Taiwan J Obstet Gynecol 62(3) (2023) 457-460. N. Ma, Z. Zhu, J. Hu, J. Pang, S. Yang, J. Liu, J. Chen, W. Tang, H. Kuang, R. Hu, Z. Li, H. Wang, Y. Peng, H. Xi, Case report: Detection of fetal trisomy 9 mosaicism by multiple genetic testing methods: Report of two cases, Front Genet 14 (2023) 1121121. A. Okumura, F. Hayakawa, T. Kato, K. Kuno, K. Watanabe, Two patients with trisomy 9 mosaicism, Pediatr Int 42(1) (2000) 89-91. C.P. Chen, T.H. Lai, S.W. Chen, S.R. Chern, F.T. Wu, P.S. Wu, Y.T. Pan, W.L. Chen, C.W. Pan, W. Wang, Low-level mosaic trisomy 9 at amniocentesis in a pregnancy associated with a favorable fetal outcome, intrauterine growth restriction, cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes and perinatal progressive decrease of the aneuploid cell line, Taiwan J Obstet Gynecol 62(3) (2023) 461-465. C. Xu, M. Li, J. Peng, Y. Zhang, H. Li, G. Zheng, D. Wang, Case report: A case report and literature review of complete trisomy 9, Front Genet 14 (2023) 1241245. D. Chitayat, K. Hodgkinson, A. Luke, E. Winsor, T. Rose, D. Kalousek, Prenatal diagnosis and fetopathological findings in five fetuses with trisomy 9, Am J Med Genet 56(3) (1995) 247-51. M.J. Seller, A. Bergbaum, M.G. Daker, Trisomy 9 in an embryo with spina bifida, Clin Dysmorphol 7(3) (1998) 217-9. W. Sepulveda, R.C. Wimalasundera, M.J. Taylor, S. Blunt, C. Be, S. De La Fuente, Prenatal ultrasound findings in complete trisomy 9, Ultrasound Obstet Gynecol 22(5) (2003) 479-83. P.R. Zen, R.F. Rosa, R.C. Rosa, C. Graziadio, G.A. Paskulin, New report of two patients with mosaic trisomy 9 presenting unusual features and longer survival, Sao Paulo Med J 129(6) (2011) 428-32. T. Hassold, Mosaic trisomies in human spontaneous abortions, Hum Genet 61(1) (1982) 31-5. D.A. Stevenson, J. Low, J. King, J.M. Opitz, M.E. Miller, Pseudoaminopterin syndrome and trisomy 9, Am J Med Genet A 128A(2) (2004) 217-8. G.R. Sutherland, R.F. Carter, L.L. Morris, Partial and complete trisomy 9: delineation of a trisomy 9 syndrome, Hum Genet 32(2) (1976) 133-40. N. Suzumori, T. Sato, J. Okada, T. Nakanishi, K. Shirai, M. Tanemura, Y. Suzuki, K. Suzumori, Prenatal findings for complete trisomy 9, Prenat Diagn 23(10) (2003) 866-8. H.S. Tang, D.G. Wang, L.Y. Huang, D.Z. Li, Chromosomal microarray analysis detects trisomy 9 mosaicism in a prenatal case not revealed by conventional cytogenetic analysis of cord blood, J Obstet Gynaecol 39(1) (2019) 123-125. G. Tonni, G. Grisolia, Ultrasound diagnosis of central nervous system anomalies (bifid choroid plexus, ventriculomegaly, Dandy-Walker malformation) associated with multicystic dysplastic kidney disease in a trisomy 9 fetus: case report with literature review, J Clin Ultrasound 41(7) (2013) 441-7. G. Tonni, M. Lituania, D. Chitayat, M.P. Bonasoni, S. Keating, M. Thompson, P. Shannon, Complete trisomy 9 with unusual phenotypic associations: Dandy-Walker malformation, cleft lip and cleft palate, cardiovascular abnormalities, Taiwan J Obstet Gynecol 53(4) (2014) 592-7. T. Williams, I. Zardawi, R. Quaife, I.D. Young, Complex cardiac malformation in a case of trisomy 9, J Med Genet 22(3) (1985) 230-3. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted 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 Advisory Board 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-6100761","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":445734081,"identity":"e16632fb-2968-4b43-bd89-1507409e883b","order_by":0,"name":"Xiao-Min Zhang","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Xiao-Min","middleName":"","lastName":"Zhang","suffix":""},{"id":445734082,"identity":"fe25a68b-0dff-44d1-afc5-bd8f1c699324","order_by":1,"name":"Yi-Qiong Yang","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Yi-Qiong","middleName":"","lastName":"Yang","suffix":""},{"id":445734083,"identity":"c2d31b09-37b1-4e18-9574-f59c197d787e","order_by":2,"name":"Yu-Ling Wang","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Yu-Ling","middleName":"","lastName":"Wang","suffix":""},{"id":445734084,"identity":"e76f8036-711b-4481-9fc2-aa1b34b12c75","order_by":3,"name":"Chen Ling","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Chen","middleName":"","lastName":"Ling","suffix":""},{"id":445734085,"identity":"c7506200-7c0e-4169-9243-aea2dc46e309","order_by":4,"name":"Li Liang","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Li","middleName":"","lastName":"Liang","suffix":""},{"id":445734086,"identity":"4ea6c3c6-62f3-4c7b-b7bd-f900ea98474f","order_by":5,"name":"Liu Ni","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Liu","middleName":"","lastName":"Ni","suffix":""},{"id":445734087,"identity":"148f456c-52ad-43be-93d6-55f10674d926","order_by":6,"name":"Hongping Huang","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Hongping","middleName":"","lastName":"Huang","suffix":""},{"id":445734088,"identity":"62605270-8223-4918-aca6-61bf8e9f28eb","order_by":7,"name":"Wenying Li","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Wenying","middleName":"","lastName":"Li","suffix":""},{"id":445734089,"identity":"51274fdb-6edf-45a6-8c29-939bced1e5ff","order_by":8,"name":"Sainan Tan","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Sainan","middleName":"","lastName":"Tan","suffix":""},{"id":445734090,"identity":"fdcff9c9-a909-437f-bf46-c816456c8110","order_by":9,"name":"Hunjin Luo","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAxklEQVRIiWNgGAWjYBACxvbGxgcfeGx47NsbiNTC3HP4sOEMmTQ5A54DRGphn5GWJs1jc9jYQCKBSC28M3KMDXhy0hK3Sz7eeIOhxiaaoBbJnjeGDyTO2CTunJ1WbMFwLC23gZAWw3agLYY9aYkNt3PMJBgbDhPWYn8AqDLx3+HEhptniNTC2JGWJnGAB+j9GzzEagEFcgNPmpxkD9AvCcT4BRSVj/8Ao5Kf/fDGGx9qbAhrQQbERw2SFlJ1jIJRMApGwcgAAL9jRJgbWdl1AAAAAElFTkSuQmCC","orcid":"","institution":"","correspondingAuthor":true,"prefix":"","firstName":"Hunjin","middleName":"","lastName":"Luo","suffix":""}],"badges":[],"createdAt":"2025-02-25 02:38:27","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6100761/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6100761/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":81694138,"identity":"ca82f081-4caa-4568-90f1-85d1e9cf4e6e","added_by":"auto","created_at":"2025-04-30 11:52:02","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":227226,"visible":true,"origin":"","legend":"\u003cp\u003eLegend not included with this version\u003c/p\u003e","description":"","filename":"figure1.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6100761/v1/d9cd6eb7d869abc33dde2e37.jpg"},{"id":81694139,"identity":"5f8b7baa-27e2-46a6-aafd-8860984068dd","added_by":"auto","created_at":"2025-04-30 11:52:02","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1413521,"visible":true,"origin":"","legend":"\u003cp\u003eLegend not included with this version\u003c/p\u003e","description":"","filename":"Figure21.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6100761/v1/0a66f5af0baabfbb93c6b923.jpg"},{"id":83934900,"identity":"37ca8fb6-c177-4601-9154-ec8a132b085e","added_by":"auto","created_at":"2025-06-04 16:08:43","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2005146,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6100761/v1/564b2841-d37c-45b1-90c3-61ffdc9a0e90.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Prenatal diagnosis of a fetus with trisomy 9 mosaicism","fulltext":[{"header":"Background","content":"\u003cp\u003eTrisomy 9 is a rare chromosomal disorder with high neonatal mortality[\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. It is generally observed in the mosaic state. The proportion of cells with trisomy 9 in different tissues is closely related to the incidence and severity of malformations and the degree of intellectual disability. In genetic counseling for mosaicism, a variety of influencing factors should be comprehensively considered, including the chromosome position, mosaicism proportion, distribution of fetal abnormal cell lines, detection method and culture method[\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. The manifestations of trisomy 9 mosaicism are diverse, the phenotype can range from no obvious abnormality to a typical phenotype, and the clinical phenotype and severity may vary with the proportion of abnormal cells. The degree of clinical variation caused by mosaicism is related to the location of the tissues with mosaicism [\u003cspan additionalcitationids=\"CR11\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Therefore, in the prenatal diagnosis of trisomy 9 mosaicism, genetic counseling for three-body chimeras is difficult; in this study, a variety of genetic methods were used to analyze cases of trisomy 9 mosaicism in fetuses[\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e"},{"header":"Case presentation","content":"\u003cp\u003eWe report the case of a 32-year-old, 20-week pregnant woman with no family history of genetic disorders or consanguineous marriage. Because Down syndrome screening indicated a high risk of Edward syndrome (trisomy 18) (ED 1/5), noninvasive prenatal testing (NIPT) was conducted at 17 gestational weeks and suggested a high risk of trisomy 9. Ultrasound suggested that the femur and humerus were less than 2 SDs for the gestational age standard. After genetic counseling was provided and informed consent was obtained, amniocentesis was recommended for prenatal diagnosis.\u003c/p\u003e \u003cp\u003eThe results of the G-banding karyotype analysis revealed 47,XX, + 9 [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]/46, XX[56], which indicated trisomy 9 with a mosaicism rate of 25.3% (Fig.\u0026nbsp;1). The results of the G-banding karyotype analysis of the peripheral blood of the woman and her husband revealed no obvious abnormalities.\u003c/p\u003e \u003cp\u003eSubsequent single nucleotide polymorphism (SNP) array analysis (HumanCytoSNP-12v2.1, Illumina) revealed arr [hg19] 9p24.3q34.3 (208455-141018648) X 2–3 (Fig.\u0026nbsp;2), which indicated trisomy 9, with a mosaicism ratio of 28%.\u003c/p\u003e \u003cp\u003eSingle nucleotide polymorphism (SNP) array analysis (HumanCytoSNP-12v2.1, Illumina) revealed arr [hg19] 9p24.3q34.3 (208455-141018648) X 2–3 (Fig.\u0026nbsp;2) and a trisomy 9 mosaicism rate of 28%.\u003c/p\u003e \u003cp\u003eTo further verify the SNP array results, fluorescence in situ hybridization (FISH) analysis was performed with a CEP9 probe and revealed nuc ish(D9Z1)×3[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]/(D9Z1)×2[91], and approximately 9% of the cells showed trisomy 9.\u003c/p\u003e \u003cp\u003eAccording to the test results, the pregnant woman was informed of the potential risks after receiving detailed genetic counseling. The pregnant woman and her family members were willing to terminate the pregnancy, and there was no obvious abnormality in the appearance of the fetus after induced labor.\u003c/p\u003e "},{"header":"Discussion and conclusion","content":"\u003cp\u003eNIPT-cell-free fetal DNA from maternal serum samples, mainly from placental trophoblasts, is not obtained directly from fetuses[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]; therefore, for NIPT-detected chromosomal aneuploidy, prenatal diagnosis is strongly recommended for pregnant women[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The mechanism of chromosomal mosaicism is complex. During meiosis of germ cells, the chromosomes of the primary oocyte do not disassociate and develop monosomy or three cells. Abnormal mitosis in early embryos can also lead to chromosomal mosaicism, but the specific molecular mechanism of mosaicism is poorly understood [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eTrisomy 9 is a common autosomal trisomy leading to miscarriage in early pregnancy [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] and usually leads to spontaneous embryo abortion, intrauterine growth restriction, and multiple congenital abnormalities [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Most fetuses with developmental disorders associated with complete trisomy 9 are lost in the early stage, and most survivors are chimeras. The clinical manifestations of trisomy 9 mosaicism are diverse and involve multiple organ system abnormalities, including craniofacial abnormalities (micropalpebral cleft, large nasal bridge, dental abnormalities, low-set ears and micrognathia, etc.), skeletal abnormalities (joint contractures, dislocations, and acrogenetic abnormalities), and cardiac abnormalities (atrioventricular septal defects are common). \"Developmental abnormalities of the urogenital system (cryptorchidism) and the central nervous system (epilepsy) [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn the prenatal diagnosis of this fetus, NIPT, amniotic fluid cell karyotype analysis, CMA, and FISH all detected trisomy 9 mosaicism, but the proportions of mosaicism were inconsistent. In prenatal diagnosis, it is regularly recommended that at least two detection techniques to detect chimerism be used to establish a diagnosis of plastic chimerism [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Therefore, in clinical practice, when mosaicism is suggested in karyotype analysis, SNP array should be used as a first-line diagnostic technique for prenatal diagnosis, or FISH should be combined with cytogenetic technology to analyze uncultured cells to further confirm the diagnosis and determine the proportion of cells with mosaicism[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eKaryotype analysis of amniotic fluid cells and CMA tests of uncultured amniotic fluid cells both suggested the presence of trisomy 9 mosaicism, and the mosaicism rates were 25.3% and 28%, respectively. In the fetal ultrasound examination, the lengths of the femur and humerus of the fetus were − 2 SDs below the corresponding gestational age standard, which did not exclude the possibility of growth restriction and skeletal dysplasia, and no other abnormal phenotypes were found[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Many researchers have revealed that the correlation analysis between the chimerism ratio and prenatal ultrasound results revealed that there was no clear correlation between the chimerism ratio and fetal ultrasound examination results, and it was not possible to predict the severity of the fetal phenotype and prognosis on the basis of the chimerism ratio. Therefore, it is very difficult to evaluate the possible phenotype of trisomy 9 mosaicism in prenatal diagnosis, which also means that genetic counseling is also challenging. In the process of counseling, it is necessary to comprehensively consider many factors, including the chromosome involved, the proportion of cells with mosaicism, and whether there is a relevant phenotype shown on ultrasound examination[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn conclusion, the diagnosis of chimerism requires the combination of multiple detection techniques. Trisomy 9 mosaicism has limited intrauterine manifestations and significant individual differences and causes multiple system abnormalities, which present great challenges for clinical prenatal diagnosis and genetic counseling for fetuses with trisomy 9 mosaicism. Therefore, combining multiple effective detection methods, case collection, and long-term prenatal and postnatal monitoring are beneficial for the future prenatal diagnosis and genetic counseling for trisomy 9 mosaicism.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e \u003cp\u003eThis study involves human participants but the Ethics Committee of the Women and Children Healthcare Hospital of Zhuzhou exempted this study. Participants gave informed consent to participate in the study before taking part.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003ePatient consent for publication\u003c/h2\u003e \u003cp\u003eConsent obtained directly from patient(s).\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eCompeting interests\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eAuthor details\u003c/h2\u003e \u003cp\u003eWomen and Children Healthcare Hospital of Zhuzhou, No. 128 Che Zhan Road, Zhuzhou 412000, Hunan Province, China. Received: 18 November 2022\u003c/p\u003e \u003c/p\u003e\u003cp\u003e\u003cb\u003eFunding Program\u003c/b\u003e: Natural Science Foundation of Hunan Province \u003cb\u003e(\u003c/b\u003e2024JJ7648); Zhuzhou Entrepreneurship and Innovation Elite Talent Project (2023)29\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eXiao-Min Zhang, and Yi-Qiong Yang carried out the clinical evaluation and collected the clinical data from the family. Liu Ni and Hongping Huang conducted the genetic counseling. Yu-Ling Wang, Chen Ling, Li Liang, Wenying Li, Sainan Tan performed the genetic testing and interpretation of the results, Hunjin Luo drafted the manuscript. All authors read and revised the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgments\u003c/h2\u003e \u003cp\u003eWe thank the family for their participation in this study.\u003c/p\u003e\u003ch2\u003eData availability\u003c/h2\u003e \u003cp\u003eThe raw data supporting the conclusions of this article will be made available by the authors on request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eE.S. Cantu, D.J. Eicher, G.S. Pai, C.J. Donahue, R.A. Harley, Mosaic vs. nonmosaic trisomy 9: report of a liveborn infant evaluated by fluorescence in situ hybridization and review of the literature, Am J Med Genet 62(4) (1996) 330-5.\u003c/li\u003e\n\u003cli\u003eG. Anneren, G. Sedin, Case report. Trisomy 9 syndrome, Acta Paediatr Scand 70(1) (1981) 125-8.\u003c/li\u003e\n\u003cli\u003eF. Stipoljev, M. Kos, M. Kos, B. Miskovi, R. Matijevic, T. Hafner, A. Kurjak, Antenatal detection of mosaic trisomy 9 by ultrasound: a case report and literature review, J Matern Fetal Neonatal Med 14(1) (2003) 65-9.\u003c/li\u003e\n\u003cli\u003eJ.C. Ferreres, S. Planas, E.A. Martinez-Saez, T. Vendrell, V. Peg, M.T. Salcedo, Y.C.S. Ramon, N. Toran, Pathological findings in the complete trisomy 9 syndrome: three case reports and review of the literature, Pediatr Dev Pathol 11(1) (2008) 23-9.\u003c/li\u003e\n\u003cli\u003eB.R. Benacerraf, S. Pauker, B.J. Quade, F.R. Bieber, Prenatal sonography in trisomy 9, Prenat Diagn 12(3) (1992) 175-81.\u003c/li\u003e\n\u003cli\u003eB.F. Carpenter, D.J. Tomkins, The trisomy 9-syndrome, Perspect Pediatr Pathol 7 (1982) 109-20.\u003c/li\u003e\n\u003cli\u003eO. Kor-Anantakul, C. Suwanrath, S. Kanngurn, S. Rujirabanjerd, T. Suntharasaj, S. Pinjaroen, Prenatal diagnosis of complete trisomy 9: a case report and review of the literature, Am J Perinatol 23(2) (2006) 131-5.\u003c/li\u003e\n\u003cli\u003eM. Li, J. Glass, X. Du, H. Dubbs, M.H. Harr, M. Falk, T. Smolarek, R.J. Hopkin, E. Zackai, S.E. Sheppard, Trisomy 9 mosaic syndrome: Sixteen additional patients with new and/or less commonly reported features, literature review, and suggested clinical guidelines, Am J Med Genet A 185(8) (2021) 2374-2383.\u003c/li\u003e\n\u003cli\u003eC.P. Chen, S.R. Chern, S.J. Cheng, T.Y. Chang, L.F. Yeh, C.C. Lee, C.W. Pan, W. Wang, C.Y. Tzen, Second-trimester diagnosis of complete trisomy 9 associated with abnormal maternal serum screen results, open sacral spina bifida and congenital diaphragmatic hernia, and review of the literature, Prenat Diagn 24(6) (2004) 455-62.\u003c/li\u003e\n\u003cli\u003eX. Liu, S. Liu, H. Wang, T. Hu, Potentials and challenges of chromosomal microarray analysis in prenatal diagnosis, Front Genet 13 (2022) 938183.\u003c/li\u003e\n\u003cli\u003eJ. Ma, D.S. Cram, J. Zhang, L. Shang, H. Yang, H. Pan, Birth of a child with trisomy 9 mosaicism syndrome associated with paternal isodisomy 9: case of a positive noninvasive prenatal test result unconfirmed by invasive prenatal diagnosis, Mol Cytogenet 8 (2015) 44.\u003c/li\u003e\n\u003cli\u003eC.P. Chen, T.M. Ko, S.W. Chen, S.R. Chern, F.T. Wu, Y.T. Pan, C.W. Pan, Y.Y. Chen, W. Wang, Low-level mosaic trisomy 9 at amniocentesis associated with a positive non-invasive prenatal testing for trisomy 9, maternal uniparental disomy 9, intrauterine growth restriction and a favorable fetal outcome in a pregnancy, Taiwan J Obstet Gynecol 62(3) (2023) 457-460.\u003c/li\u003e\n\u003cli\u003eN. Ma, Z. Zhu, J. Hu, J. Pang, S. Yang, J. Liu, J. Chen, W. Tang, H. Kuang, R. Hu, Z. Li, H. Wang, Y. Peng, H. Xi, Case report: Detection of fetal trisomy 9 mosaicism by multiple genetic testing methods: Report of two cases, Front Genet 14 (2023) 1121121.\u003c/li\u003e\n\u003cli\u003eA. Okumura, F. Hayakawa, T. Kato, K. Kuno, K. Watanabe, Two patients with trisomy 9 mosaicism, Pediatr Int 42(1) (2000) 89-91.\u003c/li\u003e\n\u003cli\u003eC.P. Chen, T.H. Lai, S.W. Chen, S.R. Chern, F.T. Wu, P.S. Wu, Y.T. Pan, W.L. Chen, C.W. Pan, W. Wang, Low-level mosaic trisomy 9 at amniocentesis in a pregnancy associated with a favorable fetal outcome, intrauterine growth restriction, cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes and perinatal progressive decrease of the aneuploid cell line, Taiwan J Obstet Gynecol 62(3) (2023) 461-465.\u003c/li\u003e\n\u003cli\u003eC. Xu, M. Li, J. Peng, Y. Zhang, H. Li, G. Zheng, D. Wang, Case report: A case report and literature review of complete trisomy 9, Front Genet 14 (2023) 1241245.\u003c/li\u003e\n\u003cli\u003eD. Chitayat, K. Hodgkinson, A. Luke, E. Winsor, T. Rose, D. Kalousek, Prenatal diagnosis and fetopathological findings in five fetuses with trisomy 9, Am J Med Genet 56(3) (1995) 247-51.\u003c/li\u003e\n\u003cli\u003eM.J. Seller, A. Bergbaum, M.G. Daker, Trisomy 9 in an embryo with spina bifida, Clin Dysmorphol 7(3) (1998) 217-9.\u003c/li\u003e\n\u003cli\u003eW. Sepulveda, R.C. Wimalasundera, M.J. Taylor, S. Blunt, C. Be, S. De La Fuente, Prenatal ultrasound findings in complete trisomy 9, Ultrasound Obstet Gynecol 22(5) (2003) 479-83.\u003c/li\u003e\n\u003cli\u003eP.R. Zen, R.F. Rosa, R.C. Rosa, C. Graziadio, G.A. Paskulin, New report of two patients with mosaic trisomy 9 presenting unusual features and longer survival, Sao Paulo Med J 129(6) (2011) 428-32.\u003c/li\u003e\n\u003cli\u003eT. Hassold, Mosaic trisomies in human spontaneous abortions, Hum Genet 61(1) (1982) 31-5.\u003c/li\u003e\n\u003cli\u003eD.A. Stevenson, J. Low, J. King, J.M. Opitz, M.E. Miller, Pseudoaminopterin syndrome and trisomy 9, Am J Med Genet A 128A(2) (2004) 217-8.\u003c/li\u003e\n\u003cli\u003eG.R. Sutherland, R.F. Carter, L.L. Morris, Partial and complete trisomy 9: delineation of a trisomy 9 syndrome, Hum Genet 32(2) (1976) 133-40.\u003c/li\u003e\n\u003cli\u003eN. Suzumori, T. Sato, J. Okada, T. Nakanishi, K. Shirai, M. Tanemura, Y. Suzuki, K. Suzumori, Prenatal findings for complete trisomy 9, Prenat Diagn 23(10) (2003) 866-8.\u003c/li\u003e\n\u003cli\u003eH.S. Tang, D.G. Wang, L.Y. Huang, D.Z. Li, Chromosomal microarray analysis detects trisomy 9 mosaicism in a prenatal case not revealed by conventional cytogenetic analysis of cord blood, J Obstet Gynaecol 39(1) (2019) 123-125.\u003c/li\u003e\n\u003cli\u003eG. Tonni, G. Grisolia, Ultrasound diagnosis of central nervous system anomalies (bifid choroid plexus, ventriculomegaly, Dandy-Walker malformation) associated with multicystic dysplastic kidney disease in a trisomy 9 fetus: case report with literature review, J Clin Ultrasound 41(7) (2013) 441-7.\u003c/li\u003e\n\u003cli\u003eG. Tonni, M. Lituania, D. Chitayat, M.P. Bonasoni, S. Keating, M. Thompson, P. Shannon, Complete trisomy 9 with unusual phenotypic associations: Dandy-Walker malformation, cleft lip and cleft palate, cardiovascular abnormalities, Taiwan J Obstet Gynecol 53(4) (2014) 592-7.\u003c/li\u003e\n\u003cli\u003eT. Williams, I. Zardawi, R. Quaife, I.D. Young, Complex cardiac malformation in a case of trisomy 9, J Med Genet 22(3) (1985) 230-3.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Trisomy 9, Mosaicism, Prenatal diagnosis","lastPublishedDoi":"10.21203/rs.3.rs-6100761/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6100761/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTrisomy 9 is a rare chromosomal disorder[1, 2]. Complete trisomy 9 is often fatal, and chromosome 9 mosaicism is commonly observed in clinical practice. Patients with this mosaicism mainly present with \"ball nose\", microphthalmia, limb dislocation, and other skeletal, cardiac, urogenital and central nervous system malformations.[3].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCase presentation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eChromosomal karyotype analysis, chromosomal microarray analysis and fluorescence in situ hybridization analysis were used for the diagnosis of a case of trisomy 9 mosaicism, and a variety of genetic testing techniques were further used for detailed analysis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe report a rare case of trisomy 9 mosaicism; fewer than five comparable cases have been reported in the literature. This case highlights the importance of genetic counseling and appropriate genetic testing for prenatal diagnosis.\u003c/p\u003e","manuscriptTitle":"Prenatal diagnosis of a fetus with trisomy 9 mosaicism","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-04-30 11:43:58","doi":"10.21203/rs.3.rs-6100761/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"25334b94-2b19-4e09-848b-649b080e6597","owner":[],"postedDate":"April 30th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-06-04T16:08:18+00:00","versionOfRecord":[],"versionCreatedAt":"2025-04-30 11:43:58","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6100761","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6100761","identity":"rs-6100761","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}