Cancer Tutorial

Problem 7: Gatekeeper and Caretaker Genes

A "gatekeeper" gene specifies a protein product that is a specific regulator of the cell cycle. The Rb gene product is an example of a gatekeeper gene, and individuals inheriting a defect in one allele have a >1000 fold increased incidence of retinoblastoma. Another class of inherited gene defects is called a "caretaker" gene that determines stability of the genome. An individual with a mutation in a caretaker gene has around a 5-50 fold increased risk of cancer (Nature 386, 762 (97). The BRCA 1 and 2 genes associated with breast cancer are now postulated to be "caretaker" genes. The best explanation for why there is a wide difference in susceptibility for cancer between caretaker and gatekeeper genes:

	The gatekeeper genes are all proto-oncogenes, with mutations leading to the formation of oncogenes that directly regulate the cell cycle and cause the cell to grow as a cancer.
	Incorrect. explanation