•Gene
promoter-region DNA methylation (continued)
–Inappropriate silencing of
tumor suppressor genes like P53 and P21 because of aberrant promoter methylation has recently been identified as a
major cause leading to cancer.
–Silencing of “junk DNA,”
repetitive sequences between genes, is thought to be a major biological role of DNA methylation.
As it turns out most of the junk is far from junk
–Abnormal methylation also
predominantly occurs at repetitive sequences, meaning herterochromatin are affected most. (inactive genes become active)
–Methylation
patterns can regulate genes
throughout life.
–The DNA methylation profiles of individuals are unique, change with
aging, and include valuable
clues to disease and treatment progress. For example, DNA methylation of
tumor suppressor genes
predicts the relapse risk in acute myeloid leukemia for patients in clinical remission.