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 Obstetrics and Gynecology, MacKay Memorial Hospital, Taipei, Taiwan.
Taiwan J Obstet Gynecol. 2022 Jul;61(4):675-676. doi: 10.1016/j.tjog.2022.05.003.
We present prenatal diagnosis of pseudomosaicism for trisomy 20 at amniocentesis with a negative non-invasive prenatal testing (NIPT) result in a pregnancy with a favorable outcome.
A 33-year-old, primigravid woman underwent amniocentesis at 17 weeks of gestation, which revealed a karyotype of 47,XX,+20[8]/46,XX[31]. Simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed the result of arr (1-22,X) × 2, consistent with no genomic imbalance. She was referred to the hospital for repeat amniocentesis at 23 weeks of gestation. At repeat amniocentesis, cultured amniocytes had a karyotype of 47,XX,+20[2]/46,XX[33]. The parental karyotypes were normal. Simultaneous aCGH analysis on the DNA extracted from uncultured amniocytes using SurePrint G3 Unrestricted CGH ISCA v2, 8 × 60 K (Agilent Technologies, Santa Clara, CA, USA) revealed no genomic imbalance, or arr (1-22,X) × 2, Y × 0. Interphase fluorescence in situ hybridization (FISH) analysis using the bacterial artificial chromosome (BAC) probes of RP11-266K16 [20q13.33; fluorescein isothiocyanate (FITC), spectrum green] and RP11-348I14 (20q11.1-q11.21; Texas Red, spectrum red) detected trisomy 20 signals in 4/104 uncultured amniocytes (3.8%), compared with 0/100 in the normal control. Polymorphic DNA marker analysis using the DNA extracted from uncultured amniocytes and parental bloods excluded uniparental disomy 20. NIPT analysis on maternal blood revealed a negative result without gene dosage increase in chromosome 20. The pregnancy was carried to term, and a healthy 2830-g female baby was delivered with no phenotypic abnormality. Both cord blood and placenta had a karyotype of 46,XX.
NIPT is useful for rapid differential diagnosis of pseudomosaicism from true mosaicism in case of mosaic trisomy 20 at amniocentesis.
我们报告了一例在羊膜穿刺术时发现三体 20 嵌合体，而无创产前检测（NIPT）结果为阴性，最终妊娠结局良好。
一位 33 岁初产妇，于妊娠 17 周行羊膜穿刺术，核型为 47,XX,+20[8]/46,XX[31]。同时对未培养的羊水细胞提取的 DNA 进行 array 比较基因组杂交（aCGH）分析，结果显示 arr（1-22,X）×2，提示无基因组不平衡。她因妊娠 23 周时需要重复羊膜穿刺术而被转诊至医院。在重复羊膜穿刺术中，培养的羊水细胞核型为 47,XX,+20[2]/46,XX[33]。父母的核型正常。同时对未培养的羊水细胞提取的 DNA 进行 aCGH 分析，使用 SurePrint G3 Unrestricted CGH ISCA v2, 8×60K（Agilent Technologies，Santa Clara，CA，USA），未发现基因组不平衡或 arr（1-22,X）×2，Y×0。应用细菌人工染色体（BAC）探针 RP11-266K16[20q13.33；异硫氰酸荧光素（FITC），绿谱]和 RP11-348I14（20q11.1-q11.21；Texas Red，红谱）的间期荧光原位杂交（FISH）分析，在 4/104 个未培养的羊水细胞（3.8%）中检测到三体 20 信号，而在正常对照中为 0/100。应用未培养的羊水细胞和父母血液提取的 DNA 进行多态性 DNA 标记分析，排除了 20 号染色体单亲二体性。对母亲血液进行的 NIPT 分析显示，20 号染色体的基因剂量无增加，结果为阴性。妊娠足月，分娩出一名无表型异常的 2830g 女性婴儿。脐带血和胎盘的核型均为 46,XX。
在羊膜穿刺术时发现三体 20 嵌合体的情况下，NIPT 可用于快速鉴别假性嵌合体与真性嵌合体。
