Accuracy of expanded noninvasive prenatal testing for maternal copy number variations: A comparative study with CNV-seq of maternal lymphocyte DNA

To evaluate the accuracy of expanded noninvasive prenatal testing (NIPT) for maternal copy number variations. Expanded NIPT was used to detect CNVs ≥2 Mb at a whole-genome scale. The threshold of maternal deletion was copy numbers (CN) ≤ 1.6, and the threshold of maternal duplication was CN ≥ 2.4. Of the 5440 pregnant women with successful expanded NIPT results, 28 maternal CNVs ≥2 Mb were detected in 27 pregnant women. Except for five cases reported as test failure, 23 CNVs ≥2 Mb were confirmed among the remaining 22 pregnant women by CNV-seq of maternal lymphocyte DNA. The genomic location, copy numbers and fragment size of maternal CNVs reported by expanded NIPT were consistent with the results of CNV-seq of maternal lymphocyte DNA. Maternal CNVs ≥2 Mb can be accurately evaluated according to the CN indicated by expanded NIPT results.