Potential diagnostic consequences of applying noninvasive prenatal testing: Population-based study from a country with existing first-trimester screening

摘要

Noninvasive prenatal testing (NIPT) for trisomies 21, 18, and 13 and sex chromosome aneuploidies is based on isolating cell-free DNA from maternal plasma. Some guidelines recommend that NIPT be used as a second-line test for women at high risk based on traditional screening programs. This retrospective, population-based study was performed to determine the risk for missing other abnormal karyotypes of probable phenotypic significance by adopting NIPT for prenatal screening or diagnosis in women who had combined first-trimester screening (cFTS). This study included parturients with singleton pregnancies undergoing nuchal translucency (NT) scanning in 2008 to 2011. Risk calculation for cFTS included maternal demographics; history of trisomy; and ultrasonographic measurement of crown-rump length (CRL), NT, and biochemistry assessments. Women with a risk of greater than 1:300 at screening were offered invasive testing. Karyotype results were classified as normal, abnormal but detectable by NIPT, atypical chromosome abnormalities, and balanced translocations. The normal group contained 46,XY and 46,XX. Abnormalities detectable by NIPT were numeric abnormalities of chromosomes 21, 18, 13, X, and Y. The group "atypical abnormal karyotypes" included karyotypes that would be missed by NIPT but would have an important phenotypic effect.