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

Abstract

Objective

To evaluate the accuracy of expanded noninvasive prenatal testing (NIPT) for maternal copy number variations.

Materials and methods

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.

Results

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.

Conclusions

Maternal CNVs ≥2 Mb can be accurately evaluated according to the CN indicated by expanded NIPT results.