We presented two cases of mosaic trisomy 2 with high risk of maternal serum screening and non-invasive prenatal testing (NIPT). The invasive amniocentesis was performed and genetic tests including karyotype, single nucleotide polymorphism array(SNP-array), interphase fluorescence in situ hybridization (FISH) were employed to detect the chromosomal abnormality. Cytogentic analysis of the case 1 and 2 showed a mosaic karyotype consisting of two cell lines (mos 47,XY,+2[8]/46,XY[19] and mos 47,XX,+2[7]/46,XX[28], respectively). SNP-array using DNA extracted from uncultured amniotic fluid cells revealed a result of arr[GRCh38](2)x2~3, which indicated that chromosome 2 may be trisomy of mosaicism in both two cases. The results of interphases FISH confirmation test showed that three red signals of the CEP 2 specific probe in 14%(14/100) and 12%(12/100) of the two cases’ cells, respectively, which indicated a mosaicism for trisomy 2 in the uncultured amniocytes. Fetal ultrasound of case 1 suggested that the long bone is smaller than the gestational age, while the case 2 showed that the biparietal diameter (BPD), head circumference (HC) and femur length (FL) were smaller than gestational age along with abnormal cardiac structure. We presented two cases with mosaic trisomy 2 and performed confirmatory genetic testing using cultured and uncultured amniocytes. When maternal serum screening and NIPT suggesting high risk, genetic counselor should be alert for increasing possibility of chromosomal anomalies if combined with abnormal ultrasound findings.

中文翻译：

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马赛克二三体的产前诊断及文献复习。

我们介绍了两例马赛克 2 三体性高危母体血清筛查和无创产前检测 (NIPT) 的病例。进行侵入性羊膜穿刺术，并采用核型、单核苷酸多态性阵列（SNP-array）、间期荧光原位杂交（FISH）等基因检测方法检测染色体异常。病例 1 和 2 的细胞遗传学分析显示由两个细胞系组成的镶嵌核型（mos 47,XY,+2[8]/46,XY[19] 和 mos 47,XX,+2[7]/46,XX [28]，分别）。使用从未培养的羊水细胞中提取的DNA进行的SNP-array显示arr[GRCh38](2)x2~3的结果，这表明在这两种情况下2号染色体都可能是嵌合三体。间期FISH确认试验结果显示，CEP 2特异性探针的三个红色信号分别在14%（14/100）和12%（12/100）的两例细胞中出现，提示存在2三体嵌合体。在未培养的羊水细胞中。病例1胎儿B超提示长骨小于胎龄，病例2显示双顶径（BPD）、头围（HC）和股骨长度（FL）小于胎龄，心脏异常结构体。我们介绍了两例马赛克三体 2 病例，并使用培养和未培养的羊水细胞进行了确认性基因检测。当母体血清筛查和 NIPT 提示高风险时，遗传咨询师应警惕如果与异常超声发现相结合，染色体异常的可能性会增加。