Chromosomal microarray in fetuses with increased nuchal translucency

ABSTRACT Objective To assess the clinical value of using high‐resolution chromosomal microarray ( CMA ) for the examination of genomic imbalances in prenatal uncultured chorionic villus samples from fetuses with increased nuchal translucency ( NT ) and a normal quantitative fluorescent polymerase chain reaction ( QF‐PCR ) result, in a clinical setting in which more than 95% of pregnant women receive first‐trimester combined screening. Methods From January 2013 to July 2014, we included 132 chorionic villus samples from consecutive ongoing pregnancies, with fetal NT ≥ 3.5 mm at 11–13 weeks' gestation, from obstetric units (publicly funded healthcare) in Central and North Denmark Regions. DNA was extracted directly from the samples and examined with QF‐PCR ( n = 132) and 180 kb oligonucleotide array‐based comparative genomic hybridization ( n = 94). Results In 38 cases, aneuploidies for chromosomes 18, 21 or X, or triploidy, were detected by QF‐PCR . Among the 94 cases with a normal QF‐PCR result, we detected pathogenic copy number variants ( CNVs ) by CMA in 12 fetuses (12.8% (95% CI , 7.5–21.0%)). In an additional three (3.2%) cases, CNVs with uncertain clinical significance were detected. Conclusion CMA is a valuable diagnostic technique in pregnancies with isolated fetal NT ≥ 3.5 mm. Copyright © 2014 ISUOG. Published by John Wiley & Sons Ltd.