Somatic Mutation


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Related to Somatic Mutation: Somatic hypermutation

somatic mutation

[sō¦mad·ik myü′tā·shən]
(genetics)
A genetic change limited to a somatic cell lineage; a major cause of cancer in humans.

Mutation, Somatic

 

a mutation that occurs in a somatic cell and provides the basis for a mosaic condition, that is, the formation of certain body parts, tissues, or cells having a unique set of chromosomes or genes.

All the types of somatic mutations that occur in sexual cells may occur in the cells of a developing organism. These mutations include (1) an increase in the chromosome set as a whole after normal chromosomal division without the subsequent division of the nucleus and cell, (2) trisomy and monosomy of various chromosomes as a result of the migration of two daughter chromosomes to a single pole (instead of different poles), and (3) the loss of a chromosome in one of the daughter cells during division as a result of its entrapment in the zone of the equatorial plate.

Inversions, deletions, and translocations of chromosomal fragments and mutations of individual genes occur with varying frequency in somatic cells. The earlier a somatic mutation occurs in an organism’s development, the greater the number of cells that will inherit the mutation, provided that the mutation does not destroy the carrier cell and that the rate of the carrier cell’s proliferation does not decrease. Gene somatic mutations are manifested relatively rarely, because in the overwhelming majority of cases the function of the mutant gene or of the separated chromosomal fragment is compensated for by the presence of a normal homologous gene or a normal area in the homologous matching chromosome of a mutant chromosome. The manifestation of certain somatic mutations is suppressed by the proximity of normal tissue.

Somatic mutations may not be manifested when the corresponding part of a chromosome of the given tissue is inactive. In the early 1960’s it was established that somatic mutations play an important role in the pathogenesis of the abnormal development of the sexual system, in the causation of spontaneous abortions and congenital deformities, and in carcinogenesis.

In plants, cells that carry somatic mutations may be propagated vegetatively or when the mutant area forms flowers.

REFERENCE

Vakhtin, Iu. B. Genetika somaticheskikh kletok. Moscow, 1974.

V. P. EFROIMSON

References in periodicals archive ?
Only 3 amplicons, which all targeted somatic mutations, had a mean coverage of <100X and were excluded from analysis.
Expression Statuses of NEIL1, NEIL2, and NEIL3 and Their Associations with the Extent of Somatic Mutation in Each Cancer Type.
Cumulative somatic mutations are one reason why cancer rates rise dramatically with age.
This research project studied the appearance of somatic mutations in six bermudagrasses commonly used on putting greens: Tifgreen, Tifdwarf, TifEagle, Champion, Floradwarf, and MS-Supreme.
While the risks of acquiring certain inherited diseases with respect to specific genetic mutations are known, the scientific community is unable to quantify accurately the statistical likelihood of developing a disease when a somatic mutation occurs.
A somatic mutation was called if the AF was ≥2% with minimum coverage up to 1000x in plasma and the AF was ≤10% with minimum coverage to 100x in PBL.
For example, somatic mutations affecting the residue Y641 of the enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2) histone methyltransferase have been identified in more than 20% of cases of the germinal center B-cell molecular subtype of diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma tumors (8, 9).
Yet they write that "in common solid tumors such as those derived from the colon, breast, brain, or pancreas, an average of 33 to 66 genes display subtle somatic mutations.
Somatic mutations of beta-catenin play a crucial role in the tumorigenesis of sporadic hepatoblastoma.
The most common activating somatic mutation in BRAF gene is a substitution of glutamic acid for V600E, which has been identified in a part of LCH cases.
This type of acquired DNA damage is referred to as somatic mutation.
The conventional theory of cancer, subscribed to by the vast majority of scientists, is the somatic mutation theory (SMT; Fardon 1953; references below).