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In whole genome sequencing of different types of cancers, large numbers of mutations were found in two breast cancers (about 20,000 point mutations [43]), 25 melanomas (9,000 to 333,000 point mutations [44]) and a lung cancer (50,000 point mutations and 54,000 small additions and deletions [45]). Genome instability is also referred to as an ...
In general, mutations in both types of genes are required for cancer to occur. For example, a mutation limited to one oncogene would be suppressed by normal mitosis control and tumor suppressor genes, first hypothesised by the Knudson hypothesis. [8] A mutation to only one tumor suppressor gene would not cause cancer either, due to the presence ...
A cancer syndrome or family cancer syndrome is a genetic disorder in which inherited genetic mutations in one or more genes predisposes the affected individuals to the development of cancers and may also cause the early onset of these cancers. Although cancer syndromes exhibit an increased risk of cancer, the risk varies.
Mutations are the immediate cause of cancer and define the tumor phenotype. Access to cancerous and normal tissue samples from the same patient and the fact that most cancer mutations represent somatic events, allow the identification of cancer-specific mutations. Cancer mutations are cumulative and sometimes are related to disease stage.
One underlying commonality in cancers is genetic mutation, acquired either by inheritance, or, more commonly, by mutations in one's somatic DNA over time. The mutations considered important in cancers are those that alter protein coding genes (the exome). As Vogelstein et al. point out, a typical tumor contains two to eight exome "driver gene ...
As with germline mutations, mutations in somatic cells may arise due to endogenous factors, including errors during DNA replication and repair, and exposure to reactive oxygen species produced by normal cellular processes. Mutations can also be induced by contact with mutagens, which can increase the rate of mutation.
In genetic counselling, parents are often told that after having a first child with a condition caused by a de novo mutation the risk of a having a second child with the same mutation is 1 – 2%. However, this does not reflect the variation in risk among different families due to genetic mosaicism. A personalised risk assessment can now ...
DNA may be modified, either naturally or artificially, by a number of physical, chemical and biological agents, resulting in mutations. Hermann Muller found that "high temperatures" have the ability to mutate genes in the early 1920s, [2] and in 1927, demonstrated a causal link to mutation upon experimenting with an x-ray machine, noting phylogenetic changes when irradiating fruit flies with ...