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A somatic mutation is a change in the DNA sequence of a somatic cell of a multicellular organism with ... Mutation can result if mistakes occur in DNA repair or ...
Deficient expression of DNA repair proteins due to an inherited mutation can cause increased risk of cancer. Individuals with an inherited impairment in any of 34 DNA repair genes (see article DNA repair-deficiency disorder) have an increased risk of cancer, with some defects causing up to a 100% lifetime chance of cancer (e.g. p53 mutations ...
The authors state that this strong relationship between somatic mutation rate and lifespan across different mammalian species suggests that evolution may constrain somatic mutation rates, perhaps by selection acting on different DNA repair pathways.
It is uncertain if transcription-based DNA repair takes part in the maintaining of somatic mutations in aging tissues. [4] In some cells, the somatically acquired alterations can be reversed back to wild type alleles by reversion mosaicism.
Signature 3 displays high mutation counts of multiple mutation classes and is associated with germline and somatic (biology) BRCA1 and BRCA2 mutations in several cancer types (e.g. breast, pancreatic, ovarian, prostate). This signature results from DNA double-strand break repair deficiency (or homologous recombination deficiency).
These are known as palindromic (P) nucleotides due to the palindromic nature of the sequence produced when DNA repair enzymes resolve the overhang. [18] The process of hairpin opening by Artemis is a crucial step of V(D)J recombination and is defective in the severe combined immunodeficiency (scid) mouse model .
In female mice, somatic cells were also found to have a higher mutation frequency than germline cells. [4] It was suggested that elevated levels of DNA repair enzymes play a prominent role in the lower mutation frequency of male and female germline cells, and that enhanced genetic integrity is a fundamental characteristic of germline cells. [4]
Somatic hypermutation (or SHM) is a cellular mechanism by which the immune system adapts to the new foreign elements that confront it (e.g. microbes).A major component of the process of affinity maturation, SHM diversifies B cell receptors used to recognize foreign elements and allows the immune system to adapt its response to new threats during the lifetime of an organism. [1]