The treatment for patients with rheumatoid arthritis (RA) has improved dramatically over the past 20 years thanks to the development of biological disease-modifying antirheumatic drugs (bDMARDs), such as tumor necrosis factor (TNF) α inhibitors (e.g., infliximab, etanercept, adalimumab, golimumab, and certolizumab pegol), interleukin-6 inhibitors (e.g., tocilizumab), and cytotoxic T-lymphocyte-associated protein 4-immunoglobulin immunoconjugates (e.g., abatacept). This evidence concerns the gene IL6 and rheumatoid arthritis.