In order to understand the real impact of the HLA-C*07 allele group on RA susceptibility, it would be relevant in future studies to include a sub-cohort of RA patients who are HLA-DRB1 SE negative, in order to define the presence of the HLA-C*07 allele group and its haplotype association with HLA-DRB1 alleles, ideally in much larger cohort of patients. The gene discussed is HLA-DRB1; the disease is rheumatoid arthritis.