CTLA4 and diabetes mellitus: Four potential TCF/LEF sites have been identified within the 800 bp upstream of the start codon in human CTLA4 [62], one of which contains the C(− 318) T SNP [63] associated with altered promoter activity [63, 64] and with susceptibility to Grave’s disease [65], autoimmune pancreatitis [66] but not diabetes [67, 68].