There is extensive evidence for the association between certain HLA-DRB1 alleles with a conserved amino acid sequence (Q/RK/RRAA) at residues 70 to 74 in the third hypervariable region of the DRβ1 chain, the so-called shared epitope (SE), and susceptibility to and severity of RA [3,4]. The gene discussed is HLA-DRB1; the disease is rheumatoid arthritis.