Repression of tumour-specific MHC-II molecules in cancers, often by hypermethylation or hypoacetylation of promoters of HLA genes and/or class II transactivator (CIITA), causes a reduction in T helper 1 (Th 1) cytokines such as IFN-γ and TNFα, which inhibit the activation of CD8+ cytotoxic T cells, eventually leading to a loss of tumour immunosurveillance [13,25,37,39]. The gene discussed is IFNG; the disease is cancer.