Prenatal diagnosis and genetic counseling of fetuses with sex chromosome mosaicism / 中华检验医学杂志

ABSTRACT

Objective:To explore the clinical significance of the combined application of prenatal cellular and molecular genetics in the diagnosis of fetal sex chromosome mosaicism.Methods:A retrospective analysis was conducted on 14 034 pregnant women aged 20-46 years (mean age 27±3 years) who came to the Genetic Counseling Clinic of the First Affiliated Hospital of Zhengzhou University from May 1st 2017 to January 31th 2020 for G-banding karyotype analysis of fetal amniotic fluid chromosomes. They were 17-32 weeks pregnant and had no consanguineous marriage. The patients diagnosed as sex chromosome mosaicism were screened out and their prenatal diagnostic indications were analyzed. The results of whole-genome copy number variation sequencing (CNV-seq)/single nucleotide polymorphism-array(SNP-array)/fluorescence in situ hybridization(FISH) were comopared, combined with ultrasound findings, and the pregnancy outcomes of all pregnant women were followed up by access to our hospital′s electronic medical record system or telephone.Results:A total of 46 cases of sex chromosome mosaicism were found. There were 43 cases with two types of karyotype mosaicism, accounting for 93.48%, and 3 cases with three types of karyotype mosaicism, accounting for 6.52%. Comparison of karyotype and CNV-seq/SNP-array/FISH results showed that 4 cases had consistent results, 9 cases had consistent results but different proportion, and 10 cases had inconsistent results. Combined with the results of the cytogenetic/molecular genetic analysis and/or ultrasound findings, pregnant women will decide to continue or terminate the pregnancy.Conclusion:The combination of prenatal cytogenetic and molecular genetic methods is helpful for rapid diagnosis of fetal sex chromosome mosaicism, providing scientific basis for pregnant women′s pregnancy selection.