GWAS studies have also identified a number of genetic variants among non-HLA genes that present a significant impact on increasing AD risk, including CTLA-4 (cytotoxic T-lymphocyte-associated antigen 4), IL-2RA (interleukin 2 receptor α), and PTPN22 (protein tyrosine phosphatase, nonreceptor-type, 22) genes [10–13]. This evidence concerns the gene CTLA4 and Alzheimer disease.