Genomic instability: DNA transitions

摘要

Somatic mutations that have been identified in human breast tumours are predominantly C-to-T transitions. Cytosine can be hydrolysed, resulting in deamination, to produce uracil. Uracil in genomic DNA can either be repaired by potentially mutagenic DNA repair pathways, or it can persist and may result in C-to-T transitions. The cytosines that seem to be prone to C-to-T transition in breast tumours are mostly unmethylated, and deamination of these residues is energetically disfavoured, indicating that enzymatic activity is occuring.