CTLA4 and autoimmune disease: Recent GWAS of common polygenic autoimmune diseases have revealed that ~60% of autoimmune-causal SNPs are mapped to non-coding enhancer regions of immune cells.44,101,102 For example, autoimmune SNPs are present in enhancer regions of T cell activation-associated genes such as IL2RA and CTLA4, which are also Treg function-associated.103–105 Yet it remains unclear whether such T cell-related autoimmune SNPs should affect the development and function of either autoimmune-causing Tconv cells or autoimmune-suppressing Treg cells.