DNAdubbelsträngsbrott

DNAdubbelsträngsbrott, also known as DNA double-strand breaks, refers to a severe type of DNA damage where both strands of the DNA double helix are severed. This is considered one of the most lethal forms of DNA damage because it disrupts the genetic information on both strands and can lead to chromosomal rearrangements, mutations, or cell death if not repaired accurately.

These breaks can occur spontaneously due to normal cellular processes like DNA replication or can be induced by external agents such as ionizing radiation, certain chemicals, and some types of chemotherapeutic drugs. The cell has evolved complex repair mechanisms to deal with DNAdubbelsträngsbrott, primarily non-homologous end joining (NHEJ) and homologous recombination (HR).

NHEJ is a quick but error-prone pathway that directly ligates the broken ends, often resulting in small insertions or deletions at the break site. HR is a more accurate repair pathway that uses a homologous DNA template, typically the sister chromatid, to guide the repair process. This pathway is generally active only during the S and G2 phases of the cell cycle when a sister chromatid is available.

The inability to properly repair DNAdubbelsträngsbrott can have significant consequences, contributing to genomic instability, which is a hallmark of cancer and can lead to developmental abnormalities. Understanding these breaks and their repair pathways is crucial for developing strategies to treat cancer and other diseases associated with DNA damage.