Application of Chromosome Microarray Analysis and Karyotype Analysis in Diagnostic Assessment of Abnormal Down's Syndrome Screening Results

Abstract

Background: Although screening for fetal aneuploidy with the use of cell-free DNA obtained from maternal plasma is highly effective, biomarkers screening is in extensive use in economically underdeveloped areas and poor population. This study aims to explore the application value of chromosomal microarray analysis (CMA) and karyotype analysis in prenatal diagnosis for pregnant women with abnormal Down’s syndrome (DS) screening results.Methods: The study recruited 813 pregnant women with abnormal DS screening results from Chengdu Women’s and Children’s Central Hospital. They underwent amniocentesis to obtain fetal amniotic fluid for CMA and G-band karyotype analysis. An Affymetrix CytoScan 750 K Array chip was used for CMA analysis according to the manufacturer’s instructions.Results: In total, CMA identified 21/813 abnormal results, which was more efficient than karyotype analysis(10/813, P<0.001.) CMA is equivalent to traditional karyotype analysis for the prenatal diagnosis of aneuploidies. However, CMA identified 1.60% more copy number variants(CNVs) than karyotype analysis. These pathogenic/likely pathogenic(P/LP) CNVs ranged from 159Kb deletion to 3616Kb deletion. 53.8% of them were recurrent pathogenic CNVs associated with risk of neurodevelopmental disorders. CMA identified 7 variants of uncertain significance (VUS) results, including 6 microduplication and 1 microdeletion, with the size ranged from 840kb-1484kb. Karyotype analysis identified 2 mosaic sex chromosome aneuploidy, 2 balanced translocation and 1 mosaic balanced translocation, which could not be identified by CMA. Conclusions: Performing both CMA and karyotype analysis simultaneously is more beneficial to pregnant women with abnormal DS screening results.