Genetics, DNA Damage, and Repair: Molecular Foundations of Cellular Integrity

Background: Deoxyribonucleic acid (DNA) serves as the fundamental blueprint for all life, and its integrity is paramount for cellular function and organismal health. However, the genome is constantly threatened by a multitude of endogenous and exogenous factors, including reactive oxygen species from metabolism, replication errors, ultraviolet (UV) radiation, and chemical mutagens. These agents cause various DNA lesions, from single-base modifications to double-strand breaks, which can lead to mutations if left unrepaired.Aim: This article aims to elucidate the molecular foundations of DNA damage and the sophisticated cellular repair mechanisms that maintain genomic stability, exploring the consequences from the biochemical to the clinical level.Methods: The review synthesizes knowledge on DNA damage types and the corresponding repair pathways, including base excision repair (BER) for oxidized bases, nucleotide excision repair (NER) for bulky adducts, mismatch repair (MMR) for replication errors, and homologous recombination/non-homologous end joining for double-strand breaks.Results: The article demonstrates that an imbalance between DNA damage accumulation and repair efficiency is a primary driver of disease. It uses examples like sickle cell disease (point mutation) and skin cancers (unrepaired UV damage) to illustrate how specific mutations and repair deficiencies lead to pathological outcomes.Conclusion: The continuous interplay between genotoxic stress and DNA repair capacity is a critical determinant of cellular fate. When repair pathways are compromised, the resulting genomic instability accelerates aging, promotes cancer, and causes a range of genetic disorders