TNFAIP3 and psoriasis: A number of single nucleotide polymorphisms (SNPs) in TNFAIP3 (A20), mainly affecting A20 expression, have been identified and linked to a number of inflammatory and autoimmune pathologies including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), inflammatory bowel disease (IBD), and psoriasis [20,21].