Detecting fetal subchromosomal aberrations by MPS: an unexpected discrepancy between amniocyte DNA and ccffDNA.

What's already known about this topic? Noninvasive prenatal detection of fetal aneuploidies by massively parallel sequencing of circulating cell-free fetal DNA has recently become widely available. Few studies report the detection of submicroscopic chromosomal aberrations. What does this study add? A ~400 kb gain and a ~27 Mb loss were detected on chromosome 13q by genomic microarray analysis of amniocyte DNA. Testing circulating cell-free fetal DNA not only revealed the same loss but also a much larger gain (~12 Mb), indicating discrepancies between DNA of true fetal and placental origin. The use of a windowed approach is recommended in case of unexpected 'whole chromosome' noninvasive prenatal testing results and/or when fetal anomalies are suggestive for subchromosomal aberrations.