CCR5 and HIV-1 infection: The CCR5/CCR2 gene cluster, which spans 20 kb on chromosome 3p21.31, has been found to be a highly diverse region with many phenotypic SNVs (Fig. 1 and Fig. 4C); thus, CCR5/CCR2 haplotypes are used for analysis of the association of candidate genes with HIV-1 infection [132, 133].