Prenatal genetic analysis and differential pregnancy outcomes of two de novo cases showing mosaic isodicentric Y chromosome

Si He,Hui Xi,Dan Wang,Jiancheng Hu,Qin Liu,Jing Chen,Jialun Pang,Zhengjun Jia,Hua Wang

doi:10.1186/s13039-020-0472-y

Abstract

BackgroundFetal cells collected from the amniotic fluid of two pregnant women indicated sex chromosome abnormalities. Therefore, we performed G-banded chromosome karyotype analysis, single nucleotide polymorphism array (SNP array), fluorescence in situ hybridization (FISH), and sequence-tagged sites (STS) analysis of the Y chromosome to determine the rare molecular genetics of the two fetuses.Case presentationThe karyotypes of the fetuses from patients 1 and 2 were mos 45,X[92]/46,X,+idic(Y)(q11.21)[8] and mos 45,X[20]/46,X,+idic(Y)(q11.223)[80], respectively. Fetus 1 had a 7.76 Mb deletion in Yq11.222q11.23 and a 15.68 Mb duplication in Yp11.2q11.21. Fetus 2 had 21 Mb of repetitive segments in Yp11.3q11.223. Azoospermia factor (AZF) detection by STS analysis revealed a missing AZFb+c region in fetus 1 and three functional AZF regions in fetus 2. The isodicentric Y chromosome (idic (Y)) in both fetuses arose de novo. The pregnancy of patient 1 was terminated, whereas the fetus of patient 2 was delivered and is now 10 months old with normal appearance and growth.ConclusionA combination of technologies such as chromosome karyotyping, FISH, SNP arrays, and STS analysis of the Y chromosome is important in prenatal diagnosis to reduce birth defect rates and improve the health of the Chinese population.

Highlights

Sex chromosome abnormalities account for ~ 0.71% [1] of all prenatal diagnoses and can cause fetal gonadal dysgenesis, structural and functional abnormalities of other organs, and mental retardation or disorders [2]
A combination of technologies such as chromosome karyotyping, fluorescence in situ hybridization (FISH), Single nucleotide polymorphism (SNP) arrays, and STS analysis of the Y chromosome is important in prenatal diagnosis to reduce birth defect rates and improve the health of the Chinese population
The two fetuses in this study were both prenatally diagnosed as having sex chromosome abnormalities; both had only one X chromosome, and one additional small supernumerary marker chromosome with an unknown structure was found in some karyotypes

Summary

Introduction

Sex chromosome abnormalities account for ~ 0.71% [1] of all prenatal diagnoses and can cause fetal gonadal dysgenesis, structural and functional abnormalities of other organs, and mental retardation or disorders [2]. We confirmed a diagnosis using G-banded chromosome karyotyping, SNP arrays, FISH, and STS analysis of the Y chromosomes. We performed G-banded chromosome karyotype analysis, single nucleotide polymorphism array (SNP array), fluorescence in situ hybridization (FISH), and sequence-tagged sites (STS) analysis of the Y chromosome to determine the rare molecular genetics of the two fetuses. The pregnancy of patient 1 was terminated, whereas the fetus of patient 2 was delivered and is 10 months old with normal appearance and growth

Methods

Results

Conclusion