Rituximab is a chimeric anti-CD20 mAb approved for the treatment of anti-TNFα non-responsive RA, Granulomatosis with Polyangiitis (GPA) and Microscopic Polyangiitis (MPA) (US Food and Drug Administration, 2012) and is used off-label in some situations such as refractory immune thrombocytopenia and lupus nephritis. The gene discussed is TNF; the disease is rheumatoid arthritis.