Apart from HLA genes, non-HLA genes have been proposed as susceptibility candidate genes for AIDs; these include genes related to modulating the immune response, such as cytotoxic T lymphocyte-associated antigen 4 (CTLA4), protein tyrosine phosphatase 22 (PTPN22), and tumor necrosis factor-alpha (TNF-α) [30]. This evidence concerns the gene CTLA4 and AIDS.