PTPN22 and type 1 diabetes mellitus: For example, variable number tandem repeat (VNTR) class I alleles upstream of the insulin gene were associated with type 1 diabetes [21,22,23]; PTPN22 was found to be associated with rheumatoid arthritis, type 1 diabetes, systemic lupus erythematosus, and Grave’s disease [24]; CTLA4 was associated with a number of autoimmune conditions including autoimmune thyroid disease, type 1 diabetes, coeliac disease [25]; and IL2RA was associated with type 1 diabetes, rheumatoid arthritis, and multiple sclerosis [2,26,27].