Immunogenetics of HLA‐B: SNP, allele, and haplotype diversity in populations from different continents and ancestry backgrounds

Abstract

HLA‐B is among the most variable gene in the human genome. This gene encodes a key molecule for antigen presentation to CD8+ T lymphocytes and NK cell modulation. Despite the myriad of studies evaluating its coding region (with an emphasis on exons 2 and 3), few studies evaluated introns and regulatory sequences in real population samples. Thus, HLA‐B variability is probably underestimated. We applied a bioinformatics pipeline tailored for HLA genes on 5347 samples from 80 different populations, which includes more than 1000 admixed Brazilians, to evaluate the HLA‐B variability (SNPs, indels, MNPs, alleles, and haplotypes) in exons, introns, and regulatory regions. We observed 610 variable sites throughout HLA‐B; the most frequent variants are shared worldwide. However, the haplotype distribution is geographically structured. We detected 920 full‐length haplotypes (exons, introns, and untranslated regions) encoding 239 different protein sequences. HLA‐B gene diversity is higher in admixed populations and Europeans while lower in African ancestry individuals. Each HLA‐B allele group is associated with specific promoter sequences. This HLA‐B variation resource may improve HLA imputation accuracy and disease‐association studies and provide evolutionary insights regarding HLA‐B genetic diversity in human populations.