Hypomethylation

**Semantic type:** Phenomenon or Process

**Definition:** An epigenetic process that either inhibits DNA methyltransferase activity or promotes DNA demethylase activity, and results in a net loss of 5-methylcytosines and a net gain of unmethylated cytosine nucleotides either in specific repetitive DNA sequences or across the bulk of the genome. This phenomenon is associated with aging, genomic instability and tumorigenesis.

**Synonyms:** - DNA Hypomethylation