Fig. 3

Haplotype bifurcation diagrams of infection-related SNPs, including rs3077 on HLA-DPA1 (upper) and rs9277542 on HLA-DPB1 (lower), in European (left) and East Asian (right). EUR and EAS in plot title refer to European and East Asian. DA and AA in plot title refer to derived allele (red) and ancestral allele (blue). Black dash line refers to the position of core SNP. Each node refers to a haplotype. The edge width reflects the population-specific frequency. Haplotype bifurcation diagrams were displayed via Rehh package. Haplotype bifurcation diagrams showed that the derived allele led to a long-range high frequency haplotype in European population and the ancestral allele led to a high frequency haplotype in East Asian population; the ancestral allele led to more haplotypes than the derived allele. The long-range high frequency haplotype confirms the genetic selection in HLA-DPA1 and HLA-DPB1 in European population