CTLA4 and systemic lupus erythematosus: Previous genetic association studies mostly focused on the promoter and exon regions of CTLA4 and ICOS. CTLA4 +49G/A, CT60A/G, −1722T/C, and −318C/T might affect the expression of CTLA4 [12–14] and was reported associated with the susceptibility to SLE, especially in Asians [15–18].