RA has a complex etiology involving non-modifiable risk factors—such as female sex, family history, and the HLA-DRB1 “shared epitope” genotype—and modifiable factors including cigarette smoking, which can increase RA risk two-to threefold, as well as obesity and silica exposure (1, 2). The gene discussed is HLA-DRB1; the disease is rheumatoid arthritis.