Contribution of chromosomal microarray analysis and next‐generation sequencing to genetic diagnosis in fetuses with normal karyotype

Aim The aim of this study was to investigate the contribution of chromosomal microarray analysis (CMA) and next‐generation sequencing (NGS) to genetic diagnosis in fetuses with normal karyotype who underwent invasive testing for different indications. Methods The results of invasive genetic testing performed at a tertiary center between September 2020 and March 2022 were retrospectively analyzed. Indications for invasive tests were classified as fetal structural malformation, presence of soft markers, and high risk in screening tests. CMA results were classified as pathogenic or likely pathogenic (pCNVs), benign (bCNVs), and variants of unknown clinical significance (VOUS). Results A total of 830 invasive tests were performed and aneuploidy was detected in 11.2% of the fetuses. CMA was performed in 465 fetuses with normal karyotype, and pCNVs were detected in 6.9%. pCNVs were detected in 8.2% of fetuses with structural malformations, 6.5% in soft markers, and 4.7% in high risk in screening tests. Pathogenic variants were detected by NGS in 33.8% of fetuses with bCNVs. Conclusions pCNVs can be significantly detected not only in fetuses with structural malformations, but also in invasive testing with other indications. NGS significantly contributes to genetic diagnosis in fetuses with structural malformations.