Genetic predisposition for this disease is supported by the following findings: (1) first degree relatives of patients with RA have a four to six times greater risk to develop the disease [5]; (2) presence of some HLA-DR molecules (HLA-DRB1*0401 and HLA-DRB1*0404) are genetic factors commonly found in RA, and its presence is associated with a more severe disease [6, 7]. The gene discussed is HLA-DRB1; the disease is rheumatoid arthritis.