The Necessity of Prenatal Diagnosis by CMA for the Women with NIPS-Positive Results

OBJECTIVE: To retrospectively analyze the results of prenatal diagnoses of noninvasive prenatal screening- (NIPS) positive pregnant women and discuss whether there is a need for chromosomal microarray analysis (CMA). METHODS: The study recruited 1,019 NIPS-positive women from two prenatal diagnostic centers. Based on clinical advice, they opted for traditional karyotype analysis or CMA. Single nucleotide polymorphism array testing was performed on a commercial 750K microarray chip (Affymetrix CytoScan 750K Array). RESULTS: Of the NIPS-positive women, 761 (74.7%) accepted the prenatal diagnosis. There were 418 (54.9%) abnormal results, and most (99.5%) were chromosome aneuploidy or structural abnormalities. Only three cases were confirmed as pathogenic copy number variation (CNVs), which were found only with CMA and not by karyotype analysis. Fifteen women were variants of uncertain significance (VUS) CNV. In addition, 300 women selected opted for both karyotype analysis and CMA for prenatal diagnosis: in 275 (91.7%) cases, the results of the two modalities were consistent, while in the remaining 25, they were not. In three cases, the additional positive results obtained with CMA were potentially clinically significant. CONCLUSIONS: CMA may not be useful for many women positive for trisomy 21/18/13 based on NIPS results, because traditional karyotype analysis can identify most problems. However, it can yield important additional findings in women positive for fetal sex chromosome aneuploidy (SCA). Further clinical studies are needed to confirm these findings.