IMPRINTING MUTATIONS ON HUMAN-CHROMOSOME-15

Genomic imprinting is an epigenetic process by which the male and the female germline of viviparous taxa confer a sex specific mark (imprint ) on certain chromosomal regions. The imprint is reset in the germline of each generation, inherited through somatic cell divisions during p ostzygotic development and used to regulate parent-of-origin specific expression of susceptible genes. Aberrant imprinting leading to aberra nt gene expression patterns represents a novel class of mutations and was first identified in patients with Angelman syndrome and Prader Wil li syndrome. The finding of inherited cis acting mutations in some of these cases has led to the identification of an imprinting center, whi ch is involved in resetting of the imprint during gametogenesis. Other mutations may interfere with the somatic inheritance of the imprint d uring postzygotic development. (C) 1997 Wiley-Liss, Inc.