Abstract
ObjectiveTo assess the positive predictive value (PPV) of noninvasive prenatal testing (NIPT) as a screening test for sex chromosome aneuploidy (SCA) with different maternal characteristics and prenatal decisions in positive cases.Materials and methodsWe retrospectively analysed 45,773 singleton pregnancies with different characteristics that were subjected to NIPT in the Maternity and Child Health Hospital of Anhui Province. The results were validated by karyotyping. Clinical data, diagnostic results, and data on pregnancy outcomes were collected.ResultsIn total, 314 cases were SCA positive by NIPT; among those, 143 underwent invasive prenatal diagnostic testing, and 58 were true-positive. Overall, the PPVs for 45,X, 47,XXX, 47,XXY and 47,XYY were 12.5%, 51.72%, 66.67% and 83.33%, respectively. Interestingly, when only pregnant women of advanced maternal age (AMA) were screened, the PPVs for 45,X, 47,XXX, 47,XXY and 47,XYY were 23.81%, 53.33%, 78.95%, and 66.67%, respectively. The frequency of SCA was significantly higher in the AMA group than in the non-AMA group. The frequencies of 47,XXX and 47,XXY were significantly correlated with maternal age.ConclusionNIPT performed better in predicting sex chromosome trisomies than monosomy X, and patients with 45,X positive foetuses were more eager to terminate pregnancy than those with 47,XXX and 47,XYY. AMA may be a risk factor of having a foetus with SCA. Our findings may assist in genetic counselling of AMA pregnant women. Our pre- and posttest counselling are essential for familiarizing pregnant women with the benefits and limitations of NIPT, which may ease their anxiety and enable them to make informed choices for further diagnosis and pregnancy decisions.
Highlights
Birth defects are structural deformities or functional abnormalities caused by congenital, genetic, or environmental factors [1]
The frequency of sex chromosome aneuploidy (SCA) was significantly higher in the advanced maternal age (AMA) group than in the non-AMA group
Before undergoing noninvasive prenatal testing (NIPT), pregnant women were subjected to screening tests, which included serological screening tests and foetal ultrasonography
Summary
Birth defects are structural deformities or functional abnormalities caused by congenital, genetic, or environmental factors [1]. Sex chromosome aneuploidy (SCA) refers to conditions caused by numerical abnormalities in X and Y chromosomes, such as Turner syndrome (45,X), triple X. 45,X is a common chromosomal disorder affecting approximately 1 in 2500 to 1 in 2000 of live-born female infants [3], the common clinical manifestations of which include congenital cardiac anomalies, renal anomalies, and acquired metabolic syndrome [3, 4]. In contrast to other trisomies, most of the girls born with triple X chromosomes do not have a characteristic physical appearance at birth, but their heights tend to be variable. 47,XXY is the most common SCA, and it occurs in 1 of every 660 males [6]. Males with 47,XXY have a higher risk of learning disabilities, developmental delays, cardiometabolic disease, typical physical symptoms and neurodevelopmental manifestations [6, 7]. The cognitive phenotype of males with 47,XYY typically includes normal to mildly diminished general intelligence [8]
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