TPMT and rheumatoid arthritis: A summary of the included studies is listed in Table 1.The earliest studies were reported in 1999 [19, 20], while the latest was in 2014 [29].4 studies[20, 23, 24, 29] were about the association between TPMT polymorphism and AZA-induced ADRs in SLE patients, 3 studies [21, 25, 26] focused on this association in AIH patients, another 3 studies [19, 22, 28] were talking about the association in patients with rheumatic diseases or RA while 1 study [27] concentrated this association in patients with autoimmune bullous diseases.