Polymorphisms, genomic imprinting and cancer susceptibility

Polymorphisms have been identified in proto-oncogenes and tumor suppressor genes that predispose people to cancer. Recent evidence indicates that geno mic imprinting, an epigenetic form of gene regulation that results in unipa rental gene expression, can also function as a cancer predisposing event. T hus, cancer susceptibility is increased by both Mendelian inherited genetic and non-Mendelian inherited epigenetic events. Consequently, chemical and physical agents cannot only induce cancer through the formation of genetic mutations but also through epigenetic changes that result in the inappropri ate expression of imprinted proto-oncogenes and tumor suppressor genes. The role of genomic imprinting in carcinogenesis and cancer susceptibility is examined in this review. (C) 1999 Elsevier Science B.V. All rights reserved .