Fig 1. Distributions of p values for disease associations of HLA-DRB variants.

P values for all variants of HLA-DRB1, HLA-DRB3, HLA-DRB4 and HLA-DRB5 were calculated by unconditional and conditional analyses testing associations with RA and SLE. The most significant association in unconditional analyses was identified at HLA-DRβ1 amino-acid position (AA) 11 and AA13 in both RA (A) and SLE (C). After conditioning on all reported disease-associated amino-acid positions of HLA-DRβ1 (11, 13, 71, and 74 in RA and 11, 13, and 26 in SLE), no additional association with p < 5 × 10⁻⁸ was identified in RA (B) or SLE (D). Variants with the lowest p value are shown for each HLA-DRB gene.