Prenatal diagnosis and molecular cytogenetic characterization of a small supernumerary marker chromosome derived from chromosome 15 in a pregnancy associated with recurrent Down syndrome |
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Authors: | Chih-Ping Chen Chia-Hao Chan Schu-Rern Chern Peih-Shan Wu Shin-Wen Chen Fang-Tzu Wu Dai-Dyi Town Meng-Shan Lee Wayseen Wang |
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Affiliation: | 1. Department of Obstetrics and Gynecology, MacKay Memorial Hospital, Taipei, Taiwan;2. Department of Medical Research, MacKay Memorial Hospital, Taipei, Taiwan;3. School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan;4. Institute of Clinical and Community Health Nursing, National Yang-Ming University, Taipei, Taiwan;5. Department of Obstetrics and Gynecology, School of Medicine, National Yang-Ming University, Taipei, Taiwan;6. Department of Medical Laboratory Science and Biotechnology, Asia University, Taichung, Taiwan;7. Department of Obstetrics and Gynecology, Hsinchu MacKay Memorial Hospital, Hsinchu, Taiwan;8. Gene Biodesign Co. Ltd, Taipei, Taiwan |
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Abstract: | ObjectiveWe present prenatal diagnosis and molecular cytogenetic characterization of a small supernumerary marker chromosome (sSMC) derived from chromosome 15 in a pregnancy associated with recurrent Down syndrome.Case reportA 33-year-old, gravida 4, para 2, woman underwent amniocentesis at 16 weeks of gestation because of a previous child with Down syndrome and a karyotype of 46,XY,der(14;21)(q10; q10),+21. In this pregnancy, amniocentesis revealed a karyotype of 47,XX,+21[12]/48,XX,+21,+mar[3]. The parental karyotypes were normal. The pregnancy was terminated, and a malformed fetus was delivered with characteristic craniofacial appearance of Down syndrome and hypoplastic middle phalanx of the fifth fingers. The placenta had a karyotype of 47,XX,+21[37]/48,XX,+21,+mar[3]. The umbilical cord had a karyotype of 47,XX,+21[38]/48,XX,+21,+mar[2]. In addition to trisomy 21, array comparative genomic hybridization (aCGH) on the DNA extracted from umbilical cord revealed 40~50% mosaicism for a 2.604-Mb duplication of 15q25.2–q25.3, or arr 15q25.2q25.3 (83,229,665–85,834,131) × 2.4 [GRCh37 (hg19)] encompassing 19 Online Mendelian Inheritance in Man (OMIM) genes. Quantitative fluorescent polymerase chain reaction (QF-PCR) using the DNAs extracted from cultured amniocytes and parental bloods revealed maternal origin of the sSMC(15) and the extra chromosome 21.Conclusion: aCGH is useful for identification of the nature of sSMC, and QF-PCR is useful for determination of the parental origin of the aberrant chromosomes. |
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Keywords: | Chromosome 15 Recurrent down syndrome Small supernumerary marker chromosome |
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