Non-invasive prenatal testing in detecting sex chromosome aneuploidy: A large-scale study in Xuzhou area of China.

BACKGROUND

Cell-free fetal DNA are widely used in the prenatal genetic testing during recent years. In the present study, we tried to investigate the clinical practical feasibility of non-invasive prenatal testing (NIPT) for prenatal sex chromosome aneuploidy (SCA) analysis among pregnancies in Xuzhou area of China.

METHODS

Among a cohort of 8384 pregnancies, maternal plasma samples from our prenatal diagnosis center was subject to the analysis for SCA using NIPT detection. The cases with positive screening results by NIPT detection were validated on karyotyping analysis.

RESULTS

From 8384 clinical pregnancies, 64 cases exhibited abnormal results detected by NIPT, in which 34 cases were false positive verified by amniotic fluid puncture and chromosome karyotyping analysis. Twelve positive Turner syndrome (monosomy X) cases in NIPT was confirmed to be sex chromosome abnormal by karyotyping analysis, in which included 9 cases of monosomy X, 1 case of mosaic (45X/47XXX), and 2 cases of mosaic with 45X/45XY karyotype. Of those 9 cases with 47XXX, 5 cases were found to be true positive. Among the ten cases of Klinefelter's syndrome (47XXY) indicated by NIPT, 6 cases (60%) were true positive. Lastly, NIPT indicated 47XYY in 9 cases. Karyotyping analysis found six cases were 47XYY, and one case was mosaic (46XY/47XYY).

CONCLUSION

Our findings showed that the true positive rate for monosomy X was lower by NIPT detection, while prediction of other SCA was relatively accurate. Therefore, NIPT could be a potential method for SCA screening, while this technique needed to be further investigated.