CTLA4 and systemic lupus erythematosus: Candidate gene association studies were widely used and found some valuable susceptibility genes such as interleukin-6,[54] Toll-like receptor 2,[55] Vitamin D receptor,[56] cytotoxic T-lymphocyte-associated protein 4,[57] Fc-gamma-RIIa,[58] FCGR2B[59] and Pellino 1.[60] More recently, as a powerful method, GWAS has been able to identify many SLE susceptibility genes and SNPs.[61–64] In view of the unsatisfactory treatment of SLE and the discovery of more and more candidate proteins.