Abstract
Human Leucocyte Antigens (HLA) constitute a highly polymorphic set of genes pivotal to the immune response. The HLA heterozygous advantage hypothesis assumes that heterozygous individuals at the HLA level have a wider range of peptides for T cell recognition than homozygous individuals. Consequently, they possess an enhanced capacity to trigger a targeted immune reaction. The divergent allele advantage hypothesis is an extension of heterozygous advantage, considering the excessive sequence divergence between alleles of the same HLA locus. The HLA Evolutionary Divergence (HED) score has been proposed to quantify this divergence between alleles of the same HLA locus. Presented here is the calculated HED (cHED), an open-source web application designed for the computation of HED scores about the 5 classical HLA genes (HLA-A, -B, -C, -DRB1, and -DQB1) when delineated at two-field resolution.