RHD Zygosity Determination from Whole Genome Sequencing Data

In the Rh blood group system, the RHD gene is bordered by two homologous DNA sequences called the upstream and downstream Rhesus boxes. The most common cause of the D− phenotype in people of European descent is a deletion of the RHD gene region, which results in a hybrid combination of the two Rhesus boxes. PCRbased testing can detect the presence or absence of the hybrid box to determine RHD zygosity. PCR hybrid box testing on fathers can stratify risk for haemolytic disease of the fetus and new born in mothers with anti-D antibodies. Red blood cells and genomic DNA were isolated from 37 individuals of European descent undergoing whole genome sequencing as part of the MedSeq Project. A whole genome sequence-based RHD sequence read depth analysis was used to determine RHD zygosity (homozygous, hemizygous, or null states) with 100% agreement (n=37) when compared to conventional RhD serology and PCR-based hybrid box assay.