Caretakers are a subgroup of tumour suppressor gene products whose major cellular function is in the mechanisms that preserve genetic stability. Inactivation of a caretaker gene typically induces an increase in the rate of genetic change, favouring the creation of somatic mutations in genes whose products regulate cell division, death or lifespan. Caretaker inactivation leads indirectly to neoplastic transformation. Caretaker gene products participate in DNA repair or the pathways that maintain chromosome stability. Examples include the breast cancer susceptibility genes BRCA1 and BRCA2, or the multiple genes mutated in different complementation groups of the disorder Xeroderma pigmentosum. Caretaker genes, such as many other genes, are often pleiotropic. They therefore can also have direct transforming ability; gatekeeper.