Prenatal diagnosis of fetuses with increased nuchal translucency using an approach based on quantitative fluorescent polymerase chain reaction and genomic microarray.

OBJECTIVE: To assess the clinical value of prenatal diagnosis of fetuses with increased nuchal translucency (NT) using an approach based on quantitative fluorescent polymerase chain reaction (QF-PCR) and chromosomal microarray (CMA).

STUDY DESIGN: From January 2013 to October 2014, we included 175 pregnancies with fetal NT ≥ 3.5mm at 11-13 weeks' gestation who received chorionic villus sampling. QF-PCR was first used to rapidly detect common aneuploidies. The cases with a normal QF-PCR result were analyzed by CMA.

RESULTS: Of the 175 cases, common aneuploidies were detected by QF-PCR in 53 (30.2%) cases (30 cases of trisomy 21, 12 cases of monosomy X, 7 cases of trisomy 18, 3 cases of trisomy 13 and 1 case of 47, XXY). Among the 122 cases with a normal QF-PCR result, microarray detected additional pathogenic copy number variants (CNVs) in 5.7% (7/122) of cases. Four cases would have expected to be detectable by conventional karyotyping because of large deletions/duplications (>10 Mb), leaving three cases (2.5%; 3/118) with pathogenic CNVs only detectable by CMA.

CONCLUSION: It is rational to use a diagnostic strategy in which CMA is preceded by the less expensive, rapid, QF-PCR to detect common aneuploidies. CMA allows detection of a number of pathogenic chromosomal aberrations in fetuses with a high NT.