Abstract
BackgroundOur aim was to evaluate the clinical utility of non-invasive prenatal testing for pregnant women with different diagnostic indications.MethodsIn eight counties and districts of Yancheng, we studied 13,149 pregnant women with different indications who were offered NIPT for fetal screening, including for sex chromosomal aneuploidies (SCAs), rare autosomal trisomies (RATs), and subchromosomal copy number variations (CNVs). The purpose was to compare the detection of positive predictive values (PPVs) of different indications with the use of NIPT. The results were validated by karyotyping, chromosomal microarray analysis (CMA), or follow-up of pregnancy outcomes.Results13,149 maternal plasma samples were sequenced, among which 28 samples (0.2%) failed the sequencing quality control. The remaining 13,121 samples were analyzed, and birth follow-up missed 2,192 samples (16.7%). The PPVs of NIPT results for trisomy 21 (T21) and trisomy 18 (T18) and SCAs were 96.67, 63.64, and 31.34%, respectively. Among the advanced maternal age (AMA), serum screening high risk (SSHR), serum screening intermediate risk (SSIR), and voluntary screening (VS) groups, the PPVs for the common trisomies were 81.25, 85.71, 100, and 70%, respectively; the PPVs for total chromosomal abnormalities were 55.82, 65.22, 23.08, and 36.59%, respectively.ConclusionNIPT for T21 and T18 and SCAs screening were ideal, and the PPVs for trisomy 13 (T13), RATs, and CNVs were low. For the AMA and VS groups, NIPT could be used as a first-line screening program; for SSHR and SSIR groups, NIPT could be used as a second-line supplementary screening program.
Highlights
At present, the total incidence of birth defects in China is about 5.6%, and about 900,000 new birth defects are added every year
Among all the NIPT-positive cases, amniocentesis was performed in 123 cases and 58 cases were confirmed by karyotyping or chromosomal microarray analysis (CMA) (Table 1), 57 cases of which were common aneuploidies, and one case was of segmental imbalances
Among the 3,079 pregnant women of the advanced maternal age (AMA) group, 12 trisomy 21 (T21), one trisomy 18 (T18), 10 sex chromosomal aneuploidy (SCA), and one copy number variation (CNV) were found by NIPT screening and prenatal diagnosis of amniotic fluid
Summary
The total incidence of birth defects in China is about 5.6%, and about 900,000 new birth defects are added every year. It is estimated that the incidence rate of trisomy 21 (T21) is approximately one in 800 births (Driscoll and Gross, 2009), but the risk increases with maternal age, reaching one in 35 for a 45year-old woman (Morris et al, 2002; Savva et al, 2006). The incidence rates of trisomy 18 (T18) and trisomy 13 (T13) are estimated to be approximately one in 6,000 and one in 10,000, respectively (Bianchi et al, 2012). The incidence rate of sex chromosomal aneuploidies (SCAs) is approximately one in 500 births (Nicolaides, 2011). The traditional methods of prenatal diagnosis in China are amniocentesis or umbilical cord blood puncture for pregnant women with high risk, such as advanced maternal age (AMA), high risk of serum screening, and abnormal sonographic indications. Our aim was to evaluate the clinical utility of non-invasive prenatal testing for pregnant women with different diagnostic indications
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