Prenatal diagnosis of mosaic trisomy 2 and literature review

Ting Wang,Jufei Lian,Laiping Zheng,Chanhui Cai,Huamei Huang,Ling Xu,Congmian Ren,Li Guo,Yanlin Huang

doi:10.1186/s13039-020-00504-3

Ting Wang, Jufei Lian + Show 7 more

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https://doi.org/10.1186/s13039-020-00504-3

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Abstract

BackgroundWe 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.ResultsCytogentic 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.ConclusionsWe 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.

Highlights

We presented two cases of mosaic trisomy 2 with high risk of maternal serum screening and noninvasive prenatal testing (NIPT)
Of 27 colonies cultured from amniotic fluid cells,8 colonies had the karyotype of 47,XY,+2 and the other 19 colonies had the karyotype of 46,XY.The abnormal cell line were obtained from two independent in situ vessels and 3 metaphases from culture A,5 metaphases from culture B
SNP-array using DNA extracted from uncultured amniotic fluid cells revealed a result of arr[GRCh38](2)×2~3 as shown in Fig. 2 which indicated that chromosome 2 may be trisomy of mosaicism in both two cases

Summary

Introduction

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. Non-invasive prenatal testing (NIPT) has developed rapidly and been widely used in the prenatal screening initially of the main autosomal non mosaic trisomies and sex chromosogwme aneuploidies. Rare autosomal trisomy (RAT) can have sometimes adverse effects on pregnancy outcomes [10, 11]. Cases indicated high risk by NIPT for trisomy 2 are rare, and cases that have been confirmed to be true fetal mosaicism with chromosome 2 have not been reported

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