Imputation of MHC class II classical HLA alleles13 in our GWAS data, analysis of classical HLA allele sequences in 20 genotyped vitiligo cases (Supplementary Table 5), and alignment with European-American MHC class II haplotype reference standards14 showed that the rs145954018del risk allele resides on an extended MHC class II haplotype, rs145954018del–HLA-DRB1*13:01–HLA-DRB3*01:01–rs9271597A–HLA-DQA1*01:03–HLA-DQB1*06:03. Here, HLA-C is linked to vitiligo.