DNA repair research explores how cells detect and correct damage to their genetic material, preserving genome stability and preventing disease. DNA is constantly assaulted by internal processes such as reactive oxygen species and replication errors, as well as external factors like ultraviolet light, ionizing radiation, and chemical mutagens. To cope with this damage, cells have evolved a network of repair pathways tailored to specific types of lesions.

Base excision repair removes small, non‑distorting base modifications, such as those caused by oxidation or deamination. Nucleotide excision repair targets bulky distortions, including UV‑induced thymine dimers. Mismatch repair corrects replication errors like mispaired bases and small insertion‑deletion loops, sharply reducing mutation rates after DNA synthesis.

Double strand breaks are especially dangerous, and two main pathways deal with them. Homologous recombination uses an intact sister chromatid as a template to restore the original sequence with high accuracy. Nonhomologous end joining instead ligates broken ends directly, which is faster but more error‑prone and can introduce small insertions or deletions.

Specialized polymerases can perform translesion synthesis, allowing replication to continue past otherwise blocking lesions at the cost of increased mutagenesis. Checkpoint signaling coordinates repair with cell cycle progression, pausing division to provide time for corrections or triggering cell death if damage is irreparable.

Defects in DNA repair genes underlie many human disorders, including cancer predisposition syndromes and neurodegenerative diseases. Understanding these pathways has led to targeted therapies, such as drugs that exploit specific repair weaknesses in tumor cells, and is central to improving genome editing accuracy and protecting cells from environmental genotoxins.