HLA-DRB1 and rheumatoid arthritis: Carriage of the HLA class I allele, HLA-Cw*06 is associated with type I but not type II psoriasis.4–13 In contrast, RA is associated with carriage of the shared epitope (SE) of the HLA class II DRB1 gene (a group of DRB1 alleles sharing a conserved amino acid motif in the third hypervariable region of the DRβ chain).14HLA-Cw*06 is not found on haplotypes encoding the SE.