Department of Obstetrics and Gynecology, MacKay Memorial Hospital, Taipei, Taiwan; Department of Medical Research, MacKay Memorial Hospital, Taipei, Taiwan; School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan; Institute of Clinical and Community Health Nursing, National Yang-Ming University, Taipei, Taiwan; Department of Obstetrics and Gynecology, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Medical Laboratory Science and Biotechnology, Asia University, Taichung, Taiwan.
Department of Obstetrics and Gynecology, Hsinchu MacKay Memorial Hospital, Hsinchu, Taiwan.
Taiwan J Obstet Gynecol. 2021 Jan;60(1):152-156. doi: 10.1016/j.tjog.2020.11.023.
We 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.
A 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.
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.
我们介绍了一例来自 15 号染色体的小额外标记染色体（sSMC）的产前诊断和分子细胞遗传学特征，该病例与复发性唐氏综合征相关。
一位 33 岁，孕 4 产 2 的女性，因前一个孩子患有唐氏综合征且核型为 46,XY,der(14;21)(q10; q10),+21，故在妊娠 16 周时接受了羊膜穿刺术。在此妊娠中，羊膜穿刺术显示核型为 47,XX,+21[12]/48,XX,+21,+mar[3]。父母的核型正常。妊娠终止，分娩出一个具有唐氏综合征特征性颅面外观和第五指中节指骨发育不良的畸形胎儿。胎盘核型为 47,XX,+21[37]/48,XX,+21,+mar[3]。脐带核型为 47,XX,+21[38]/48,XX,+21,+mar[2]。除了 21 三体之外，从脐带提取的 DNA 进行的 array 比较基因组杂交（aCGH）显示 15q25.2-q25.3 区域存在 40∼50%嵌合体性 2.604-Mb 重复，或染色体 15q25.2q25.3（83,229,665-85,834,131）×2.4 [GRCh37（hg19）]，包含 19 个在线孟德尔遗传数据库（OMIM）基因。使用从培养的羊水细胞和父母血液中提取的 DNA 进行定量荧光聚合酶链反应（QF-PCR）显示 sSMC（15）和额外的 21 号染色体来自母亲。
aCGH 有助于识别 sSMC 的性质，QF-PCR 有助于确定异常染色体的亲本来源。
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