Mutations and polymorphisms in the A20/TNFAIP3 gene have been associated with a plethora of (auto)inflammatory and autoimmune pathologies, including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and A20 haploinsufficiency (HA20)3–7. This evidence concerns the gene TNFAIP3 and rheumatoid arthritis.