DNA damage

DNA damage refers to chemical or structural alterations of the genome, including base modifications, single- and double-strand breaks, and crosslinks. It arises from reactive oxygen species, ionising radiation, UV light, and replication stress. Cells respond through DNA damage repair pathways; when overwhelmed, damage triggers senescence, apoptosis, or mutations. Genomic instability driven by accumulated DNA damage is a recognised hallmark of ageing and a cancer driver.