Determination of RHD zygosity and RH hybrid alleles, by using sequencing coverage by RHtyper. (A) RHtyper determined RHD homozygous and hemizygous deletions by comparing the sequencing coverage across the entire RHD region with the average coverage of the whole genome. The distribution of log2-transformed coverage ratios of RHD and RHCE regions of samples SJSCD040770 (no RHD deletion), SJSCD040771 (hemizygous RHD deletion), and SJSCD040777 (homozygous RHD deletion) are shown. Blue and red dotted lines represent the cutoff for the hemizygous (−0.6) and homozygous (−3) deletions, respectively. (B) RHtyper predicted hybrid alleles by their characteristic SNPs and indels supplemented by sequencing coverage profiling. The potential boundaries of the hybrid alleles are predicted by the CBS algorithm, using sequencing coverage. The distribution of log2-transformed coverage ratios of RHD and RHCE genes and the potential hybrid boundaries of sample SJSCD040934 [RHD/RHD*D-CE(4-7)-D] are shown. Each dot represents a 300-bp segment. Segments of introns are indicated by blue dots, and segments of exons are indicated by colors other than blue. The boundaries of the hybrid allele are indicated by vertical gray lines with the genomic location of the potential breakpoints labeled.