Dictionary of Human Evolution and Biology

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Retinoblastoma

Rare form of eye cancer in infants characterized by bilateral tumors in the retina of the eye, and a predisposition to bone cancer. An inherited autosomal germline mutation plus a new somatic mutation are both required in the hereditary form. The affected gene is Rb1, portions of which are abnormally deleted from chromosome 13 in the cells of an immature retina. The normal function of Rb1 in other body cells is to act as a tumor suppressor by preventing certain regulatory proteins from initiating DNA replication (Cf. the p53 tumor suppressor). Retinoblastoma exhibits evidence for genomic imprinting; there are also indications of a paternal age effect. Other mutations to the Rb1 gene cause cancers in other types of cells. Sporadic, nonhereditary, unilateral forms of retinoblastoma also exist, in which two simultaneous somatic mutations are required.

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