What role does imprinting play in disease?
Because of their growth-related aspects, imprinted genes likely play a major role in the development of cancer and other conditions in which cell and tissue growth is abnormal. Imprinted genes in which the copy from the mother is turned on (maternally expressed) usually suppress growth, while paternally expressed genes usually stimulate growth. In cancer, some tumor suppressor genes are actually maternally expressed genes that are mistakenly turned off, preventing the growth-limiting protein from being made. Likewise, many oncogenes — growth-promoting genes — are paternally expressed genes for which a single dose of the protein is just right for normal cell proliferation. However, if the maternal copy of the oncogene loses its epigenetic marks and is turned on as well, uncontrolled cell growth can result. In the collection of birth defects known as Beckwith-Wiedemann syndrome (BWS), abnormal epigenetics leads to abnormal growth of tissues, overgrowth of abdominal organs, and low bloo
