DNA methylation in genomic imprinting, development, and disease

Changes in DNA methylation profiles are common features of development and in a number of human diseases, such as cancer and imprinting disorders like Beckwith-Wiedemann and Prader-Willi/Angelman syndromes. This suggests that DNA methylation is required for proper gene regulation during development and in differentiated tissues and has clinical relevance. DNA methylation i s also involved in X-chromosome inactivation and the allele-specific silenc ing of imprinted genes. This review describes possible mechanisms by which DNA methylation can regulate gene expression, using imprinted genes as exam ples. The molecular basis of methylation-mediated gene regulation is relate d to changes in chromatin structure and appears to be similar for both impr inted and biallelically expressed genes. Copyright (C) 2001 John Wiley & So ns, Ltd.