CTLA4 and systemic lupus erythematosus: The SNP of CTLA-4 +49A/G locus (rs231775) has a gene dosage effect on the levels of sCTLA-4 [8]; therefore, CTLA-4 +49A/G polymorphism has been widely studied in autoimmune diseases, and it has been reported to be involved in the development of Graves’ disease (GD) [9], systemic lupus erythematosus (SLE) [10], and diabetes mellitus [11].