A gene that encodes a protein involved in controlling cellular growth; inactivation of this type of gene leads to deregulated cellular proliferation, as in cancer. See Also: oncogene. Syn: antioncogene.
In a person born with two normal copies of a tumor suppressor gene, both copies must be inactivated by spontaneous point mutation, deletion, or failure of expression before tumor formation occurs. An inherited mutation in a tumor suppressor gene is the basis of most familial predispositions to cancer. In a person so predisposed, malignant cellular proliferation does not occur until the remaining intact copy of the gene is inactivated by deletion of part or all of its chromosome. Of many tumor suppressor genes thus far identified, the p53 gene on chromosome 17, which encodes a phosphoprotein that suppresses cell proliferation, appears to be the most important. Mutations of p53 have been found in the DNA of more than half of all human cancers studied. Li-Fraumeni syndrome, characterized by early-onset carcinomas and sarcomas, is an inherited (autosomal dominant) mutation in the p53 tumor suppressor gene. BRCA1 and BRCA2, involved in familial early-onset breast cancer as well as ovarian and other cancers in people of both sexes, are tumor suppressor genes.
Reference: Stedman's Medical Dictionary