DNA methylation changes in gastrointestinal disease
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DNA methylation of the 5′ region of genes is often associated with gene silencing in X-chromosome inactivation and imprinting. Recent studies have indicated that altered DNA methylation plays a role in the inactivation of multiple tumor suppressor genes and DNA repair genes such as pl6INK4A and hMLHl. Colorectal adenomas have a relatively high frequency of methylation, and aberrant methylation is an early event during tumorigenesis. In aging patients, even colon epithelium which appears to be normal showed a significant amount of methylation in a subset of the genes. Colon mucosa from patients with inflammatory bowel disease also showed a high level of methylation. DNA methylation can be a specific diagnostic marker in gastrointestinal cancer and inflammatory bowel disease, for which there is no perfect marker for a noninvasive diagnosis.
KeywordsCpG island methylator phenotype chromatin molecular diagnosis
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