HLA-DPB1 and rheumatoid arthritis: The strongest genetic associations with RA susceptibility lie with the HLA region and the seminal study by Raychaudhuri et al showed that amino acid polymorphisms at HLA-DRB1, HLA-B and HLA-DPB1 explain most of the statistical association.38 HLA imputation using HLA-TAPAS and linear models via PLINK were employed to assess the association of eQTLs with RA phenotypes in the HLA region.