OBJECTIVETo assess the value of whole-genome high-resolution chromosome microarray analysis (CMA) for the investigation of fetuses with ultrasound abnormalities.

METHODSWhole genome high-resolution CytoScanHD array from Affymetrix was employed to investigate 651 fetuses with structural abnormalities detected by ultrasound, for whom standard G-banded chromosome analysis has revealed a normal karyotype. The fetuses were divided into a single malformation group (n=264) and a multiple malformations group (n=387). In total there were 130 chorionic villus samples, 192 amniotic fluid samples and 329 cord blood samples. Extraction of fetal DNA and CMA experiment have followed the standard guidelines from the manufacturers. All copy number variations (CNVs) detected by CMA were confirmed by fluorescence in situ hybridization (FISH) or real-time polymerase chain reaction (RT-PCR).

RESULTSCMA analysis has detected genomic CNVs in 475 (73%) cases. Clinically significant CNVs were found in 11.5% (75/651) of fetuses, including two uniparental disomies (UPD) and two cryptic mosaicisms. Variations of unknown significance (VOUS) was found in 2.0% (13/651) of tested fetuses.

CONCLUSIONAbove results have suggested that whole-genome and high-resolution CMA is valuable for the analysis of fetuses with structural abnormalities detected by ultrasound, which can increase the detection rate by approximately 11%. CMA using single nucleotide polymorphism (SNP) array has the ability to detect UPD and low-level mosaicisms. Sufficient communication between technicians and genetic counselors, parental testing and comparison the results with in-house and relevant online databases can significantly reduce the rate of VOUS.