Prenatal diagnosis of mosaic trisomy 2 and literature review
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RESEARCH
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Prenatal diagnosis of mosaic trisomy 2 and literature review Ting Wang, Jufei Lian, Congmian Ren, Huamei Huang, Yanlin Huang, Ling Xu, Laiping Zheng, Chanhui Cai and Li Guo*
Abstract Background: We presented two cases of mosaic trisomy 2 with high risk of maternal serum screening and noninvasive 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. Results: 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. Conclusions: 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. Keywords: Non-invasive prenatal testing, Trisomy 2, Mosaicism, Single nucleotide polymorphism array, Fluorescence in situ hybridization, Chromosomal abnormality, Prenatal diagnosis
Background Complete trisomy 2 is a lethal chromosomal abnormality, accounting for 1% to 5–6% in early pregnancy and 1.1% in all spontaneous abortions [1]. It is estimated that the prevalence of trisomy 2 mosaicism in chorionic villi sampling (CVS) is about 1/2000 ([2–4] (Sifakis)), compared with about 1/58000 in amniocentesis during the second trimester ([5] (Sago)). In addition, the frequency of pseudomosaicism in * Correspondence: [email protected] Medical Genetic Center, Guangdong Women and Children Hospital, Guangzhou,Chi531 Xinnan Road, Panyu District, Guangzhou, China
trisomy 2 was the highest among all chromosomes in the karyotype analysis of amniotic fluid cell culture ([6, 7] (Hsu)). However, case reports of true fetal mosaicism of trisomy 2 are extremely rare. Up to present, only 21 cases of mosaic trisomy 2 have been reported in the prenatal diagnosis via amniocentesis or CVS. The prenatal manifestations of fetus with true mosaic trisomy 2 are quite variable, mainly including intrauterine growth restriction (IUGR),cerebral ventriculomegaly, oligohydramn
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