HLA-DRB1 and primary biliary cholangitis: Previous interrogation of the UK PBC case/control data set risk [13] using classical HLA alleles imputed using the package HLA*IMP:01 [18, 19] had revealed four haplotypes showing independent disease associations: the well-established association at HLA-DQA1*04:01 (which forms a haplotype with HLA-DQB1*04:02 and HLA-DRB1*08:01), two previously identified protective effects marked by alleles HLA-DQB1*06:02 [20] and HLA-DQB1*03:01 [1], and a novel association marked by the haplotype HLA-DRB1*04:04/HLA-DQB1*03:02.