Some tumor suppressor genes, e.g., RB1 and CDKN1C, can be downregulated or inactivated in cancer via promoter hypermethylation or copy number loss [52, 76, 177, 178], inactivating mutations in RB1 [177] or imprinting allele switching of CDKN1C [52]. The gene discussed is CDKN1C; the disease is cancer.