These include female gender, family history of RA, age, smoking, and genetic factors, including the Human Leukocyte Antigen (HLA) and non-HLA such as polymorphisms of PTPN22, STAT-4, tumor necrosis factor-α (TNF-α), T-cell receptor (TCR), and Fc-γ receptor (Fc-γR), among others. The gene discussed is TNF; the disease is rheumatoid arthritis.