Different from the empirical data-based model presented here, the above-mentioned gene association study suggested that SLE disease risk conferred by allele DRB1*03:01 is attributable to a single amino acid residue located at the peptide binding groove: Tyr26 in the risk allele DRB1*03:01 versus Phe26 in the non-risk allele, DRB1*03:02, indirectly implicating antigen presentation. The gene discussed is HLA-DRB1; the disease is systemic lupus erythematosus.