HLA-DRB1 and systemic lupus erythematosus: Amino acid haplotype decreased SLE risk in HLA-DR1 (11Leu-13Phe-26Leu) and HLA-DR13 (11Ser-13Ser-26Phe) and increased SLE risk in HLA-DR16 (11Pro-13Arg-16Phe) [48], which showed that the residues in peptide binding groove of HLA-DRB1 molecule may have an impact on SLE susceptibility.