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 Chiao Tung University, Taipei, Taiwan; Department of Obstetrics and Gynecology, School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan; Department of Medical Laboratory Science and Biotechnology, College of Medical and Health Science, Asia University, Taichung, Taiwan.
Department of Obstetrics and Gynecology, MacKay Memorial Hospital, Taipei, Taiwan.
Taiwan J Obstet Gynecol. 2023 Nov;62(6):891-895. doi: 10.1016/j.tjog.2023.09.002.
We present low-level mosaic trisomy 21 at amniocentesis in a pregnancy associated with cytogenetic discrepancy in various tissues, perinatal progressive decrease of the trisomy 21 cell line and a favorable fetal outcome.
A 36-year-old, gravida 2, para 1, woman underwent amniocentesis at 18 weeks of gestation because of advanced maternal age, and the result was 47,XY,+21 [8]/46,XY [26]. Prenatal ultrasound findings were unremarkable. She was referred for genetic counseling, and repeat amniocentesis performed at 23 weeks of gestation revealed the result of 47,XY,+21 [3]/46,XY [21]. The parental karyotypes were normal. At repeat amniocentesis, quantitative fluorescent polymerase chain reaction (QF-PCR) analysis using the DNA extracted from uncultured amniocytes and parental bloods excluded uniparental disomy (UPD) 21, array comparative genomic hybridization (aCGH) analysis on uncultured amniocytes revealed the result of arr 21q11.2q22.3 × 2.4, consistent with 40% mosaicism for trisomy 21, and fluorescence in situ hybridization (FISH) analysis on uncultured amniocytes revealed 67% (67/100 cells) mosaicism for trisomy 21. The woman was advised to continue the pregnancy, and a 1370-g male baby was delivered prematurely at 29 weeks of gestation without phenotypic abnormalities. The karyotypes of umbilical cord and placenta were 47,XY,+21 [13]/46,XY [27] and 47,XY,+21 [40], respectively. QF-PCR determined maternal origin of the extra chromosome 21 of trisomy 21 in the placenta. When follow-up at age 8½ months, the neonate was normal in appearance and development. The peripheral blood had a karyotype of 47,XY,+21 [1]/46,XY [39], and FISH analysis on buccal mucosal cells showed 9.7% (11/113 cells) mosaicism for trisomy 21, compared with 2% (2/100 cells) in the normal control.
Low-level mosaic trisomy 21 at amniocentesis can be associated with cytogenetic discrepancy in various tissues, perinatal progressive decrease of the trisomy 21 cell line and a favorable fetal outcome.
我们呈现了一例在羊水穿刺中发现的低水平嵌合三体 21 病例，该病例与不同组织中的细胞遗传学差异、围产期三体 21 细胞系逐渐减少以及良好的胎儿结局有关。
一位 36 岁、孕 2 产 1 的女性因高龄接受了 18 周的羊水穿刺检查，结果显示 47,XY,+21[8]/46,XY[26]。产前超声检查未见异常。她被转介进行遗传咨询，并在 23 周时再次进行羊水穿刺检查，结果显示 47,XY,+21[3]/46,XY[21]。父母的核型正常。在再次进行羊水穿刺时，使用未培养的羊水细胞和父母血液提取的 DNA 进行定量荧光聚合酶链反应（QF-PCR）分析排除了 21 号染色体单亲二体（UPD），对未培养的羊水细胞进行 array 比较基因组杂交（aCGH）分析显示结果为 arr 21q11.2q22.3×2.4，符合三体 21 的 40%嵌合体，未培养的羊水细胞荧光原位杂交（FISH）分析显示三体 21 的嵌合体率为 67%（67/100 个细胞）。建议该女性继续妊娠，一名 1370 克的男性婴儿于 29 周早产，无表型异常。脐带和胎盘的核型分别为 47,XY,+21[13]/46,XY[27]和 47,XY,+21[40]。QF-PCR 确定了胎盘三体 21 额外染色体 21 的母源来源。随访至 8 个半月时，新生儿外观和发育正常。外周血核型为 47,XY,+21[1]/46,XY[39]，颊黏膜细胞 FISH 分析显示三体 21 的嵌合体率为 9.7%（11/113 个细胞），而正常对照组为 2%（2/100 个细胞）。
羊水穿刺中低水平嵌合三体 21 可与不同组织中的细胞遗传学差异、围产期三体 21 细胞系逐渐减少以及良好的胎儿结局有关。
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