目的:我们介绍了在羊膜穿刺术和宫腔穿刺术中低水平镶嵌21三体与良好的胎儿结局相关的妊娠。
方法:26岁,初产妇在妊娠17周时接受了羊膜穿刺术,因为在妊娠16周时21三体的非侵入性产前检测(NIPT)阳性。羊膜穿刺术显示核型为47,XX,+21[3]/46,XX[17],未培养羊膜细胞上的多重连接依赖性探针扩增(MLPA)显示rsaX(P095)×2,(13,18,21)×2。她在妊娠21周时接受了脐带穿刺术(脐带血采样),结果显示核型为47,XX,+21[2]/46,XX[48]。妊娠27周时,她被转诊到我们医院接受遗传咨询,重复羊膜穿刺术显示20/20个菌落的核型为46,XX。对从未培养的羊膜细胞和亲本血液中提取的DNA进行定量荧光聚合酶链反应(QF-PCR)分析,排除了单亲二体(UPD)21。对从未培养的羊膜细胞提取的DNA进行的阵列比较基因组杂交(aCGH)分析显示arr(1-22,X)×2,Y×0,没有基因组失衡。对104个未培养的羊膜细胞进行间期荧光原位杂交(FISH)分析,检测到一个细胞(1/104=0.9%)具有三体性21,而其余细胞为二体性21,而正常对照组为0%(0/100)。该妇女被鼓励继续怀孕。妊娠持续到妊娠38周,一名2771g女婴分娩时无表型异常。脐带血的CGH分析显示ARR(1-22,X)×2,Y×0没有基因组失衡。脐带的核型为47,XX,+21[3]/46,XX[37]。胎盘的核型为46,XX。在3½个月的年龄进行随访时,新生儿表型正常,发育正常。外周血中40/40细胞的核型为46,XX。口腔粘膜细胞的间期FISH分析检测到100/100细胞中的正常二体21细胞。
结论:孕中期羊膜穿刺术和宫腔穿刺术中低水平镶嵌21三体与围产期21三体细胞系逐渐减少和良好的胎儿结局有关。
OBJECTIVE: We present low-level mosaic trisomy 21 at amniocentesis and cordocentesis in a pregnancy associated with a favorable fetal outcome.
METHODS: A 26-year-old, primigravid woman underwent amniocentesis at 17 weeks of gestation because of positive non-invasive prenatal testing (NIPT) for trisomy 21 at 16 weeks of gestation. Amniocentesis revealed a karyotype of 47,XX,+21[3]/46,XX[17], and multiplex ligation-dependent probe amplification (MLPA) on uncultured amniocytes revealed rsa X(P095) × 2, (13, 18, 21) × 2. She underwent cordocentesis (cord blood sampling) at 21 weeks of gestation which revealed a karyotype of 47,XX,+21[2]/46,XX[48]. At 27 weeks of gestation, she was referred to our hospital for genetic counseling, and repeat amniocentesis revealed a karyotype of 46,XX in 20/20 colonies. Quantitative fluorescent polymerase chain reaction (QF-PCR) analysis on the DNA extracted from uncultured amniocytes and parental bloods excluded uniparental disomy (UPD) 21. Array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed arr (1-22,X) × 2, Y × 0 with no genomic imbalance. Interphase fluorescence in situ hybridization (FISH) analysis on 104 uncultured amniocytes detected one cell (1/104 = 0.9%) with trisomy 21, while the rest cells were disomy 21, compared with 0% (0/100) in the normal control. The woman was encouraged to continue the pregnancy. The pregnancy was carried to 38 weeks of gestation, and a 2771-g female baby was delivered no phenotypic abnormality. aCGH analysis on the cord blood showed arr (1-22,X) × 2, Y × 0 with no genomic imbalance. The umbilical cord had a karyotype of 47,XX,+21[3]/46,XX[37]. The placenta had a karyotype of 46,XX. When follow-up at age 3½ months, the neonate was phenotypically normal and had normal development. The peripheral blood had a karyotype of 46,XX in 40/40 cells. Interphase FISH analysis on buccal mucosal cells detected normal disomy 21 cells in 100/100 cells.
CONCLUSIONS: Low-level mosaic trisomy 21 at amniocentesis and cordocentesis in the second trimester can be associated with perinatal progressive decrease of the trisomy 21 cell line and a favorable fetal outcome.