Analysis of the clinical screening value of extended noninvasive prenatal genetic testing

Objective To research the clinical screening value of extended noninvasive prenatal genetic testing(NIPT-plus).

Methods A total of 7 331 pregnant women who received NIPT-plus and 48 829 pregnant women who received conventional non-invasive prenatal genetic testing(NIPT) during the same period were selected.For pregnant women with high-risk screening results, the karyotype analysis and chromosomal microarray detection technology(CMA) were used to further confirm the diagnosis.The detection rate, combined positive predictive value(PPV) and single PPV bewteen two screening methods were compared.

Results A total of 690 pregnant women received follow-up diagnosis and obtained diagnosis results, 128 cases of which were high-risk reports of NIPT-plus, and 65 cases were consistent with diagnosis results.Five hundred and sixty-two cases were reported as high-risk through conventional NIPT, and 285 cases were confirmed to be consistent with the diagnostic results.The total PPVs were 50.78% and 50.71%, respectively, and the difference of which was no statistical significance(P>0.05).Further subdividing, the PPVs of NIPT-plus for T13, T18, T21, sex chromosome abnormalities (SCAs), rare chromosome abnormalities (RCAs), and copy number variations (CNVs) were 33.33%, 61.54%, 91.31%, 40.00%, 16.67% and 51.43%, respectively.The PPVs of NIPT were 36.99%, 59.09%, 89.94%, 35.19%, 20.00% and 42.20%, respectively, and the differences of which was no statistical significance(P>0.05).There was no statistical significance in the detection rates of T13, T21, SCAs and RCAs between two methods(P>0.05), but there were a statistically significant in the total detection rate of T18 and CNVs(P < 0.01).

Conclusions Conventional NIPT and NIPT-plus have similar screening values for T13, T21, SCAs, and RCAs, while conventional NIPT has a higher cost-effectiveness.The detection rate of T18 and CNVs by NIPT-plus is higher than that of conventional NIPT, and NIPT-plus has better screening value for chromosomal microdeletions and microduplications.