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Accumulation of DNA double strand breaks can lead to cell cycle arrest in somatic cells and cause cell death. Due to its ability to induce cell cycle arrest, ionizing radiation is used on abnormal growths in the human body such as cancer cells, in radiation therapy.
DNA damage in non-replicating cells, if not repaired and accumulated can lead to aging. DNA damage in replicating cells, if not repaired can lead to either apoptosis or to cancer. The schematic diagram indicates the roles of insufficient DNA repair in aging and cancer, and the role of apoptosis in cancer prevention.
The somatic mutations and epigenetic alterations caused by DNA damage and deficiencies in DNA repair accumulate in field defects. Field defects are normal-appearing tissues with multiple alterations (discussed in the section below), and are common precursors to development of the disordered and over-proliferating clone of tissue in a cancer.
Somatic evolution is the accumulation of mutations and epimutations in somatic cells (the cells of a body, as opposed to germ plasm and stem cells) during a lifetime, and the effects of those mutations and epimutations on the fitness of those cells.
Larger radiation doses are more prone to cause tighter clustering of damage, and closely localized damage is increasingly less likely to be repaired. [39] Somatic mutations cannot be passed down from parent to offspring, but these mutations can propagate in cell lines within an organism. Radiation damage can also cause chromosome and chromatid ...
The disparity in mutation rate between the germline and somatic tissues likely reflects the greater importance of genetic integrity in the germline than in the soma. [12] Variation in mutation frequency may be due to differences in rates of DNA damage or to differences in the DNA repair process as a result of elevated levels of DNA repair enzymes.
In somatic cells, deficiencies in DNA repair sometimes arise by mutations in DNA repair genes, but much more often are due to epigenetic reductions in expression of DNA repair genes. Thus, in a sequence of 113 colorectal cancers, only four had somatic missense mutations in the DNA repair gene MGMT, while the majority of these cancers had ...
This cell death can occur due to an accumulation of DNA damage in the presence of improperly functioning DNA structure checkpoints or an improperly functioning spindle assembly checkpoint. [2] Cells that undergo mitotic catastrophe death can lack activation of pathways of the traditional death pathways such as apoptosis. [7]