A blue lobster (one in two million), an example of a genuine mutant.

A deformed banana, probably a developmental abnormality, not a mutant.

A mutant is an individual, organism, or new genetic character arising or resulting from an instance of mutation, which is a sudden structural change within the DNA of a gene or chromosome of an organism resulting in the creation of a new character or trait not found in the wildtype. In an organism or individual, the new character or trait may or may not be trivial, may occasionally be beneficial, but will usually result in either a genetic disorder or have no phenotypic effect whatsoever. The natural occurrence of genetic mutations is integral to the process of evolution. A more general term for mutant is sport, which includes individuals who vary from type due to mutation, as well as those who vary from type due to other reasons.

Developmental abnormalities not due to genetic change, are frequently referred to as mutants by non-experts. The difference between a developmental abnormality and a mutation is that the former is non-hereditable as the DNA is unchanged. Such abnormalities include extra limbs and occur when a genetically normal embryo develops abnormally.

Occasionally, a body cell in a healthy organism may acquire a mutation caused by a genetic error occurring during routine cell division. This is also known as a "somatic mutation". Such an error may result in cancer.

Creatures with visibly obvious mutations are often regarded as objects of curiosity. Examples include rare blue lobsters,^[1] albinos of many species^[2][3] and animals with extra digits.^[4] A well-known mutation in fruit flies causes the flies to have legs in place of antennas.^[5] An American aquarium even displays what it calls a "double mutant" snake that is both albino and has two heads^[6], though calling this a double mutation is a misnomer as the two-headed condition is a developmental abnormality and not a genetic mutation.

Similarly striking human mutations also occur occasionally. People who are completely covered in a fur-like coat of hair are one example (see hypertrichosis). There are also cases of newborn babies having an extended tailbone or a sixth finger. Purely internal, less obvious mutations are more common; a small fraction of these cause serious medical conditions or death. (The ratio is probably under 1.5%, as only about 1.5% of the genome encodes protein genes)^[7]

Wild type

Wild type (sometimes written wildtype, wild-type or +) is the genetic term used in texts for the typical form of an organism, strain, gene, or characteristic as it was first observed in nature.^[8][9] Wild type refers to the most common phenotype in the natural population; however this may, over a period of time, be replaced by a mutant form, which then becomes the new wildtype. The phenotype can be dominant or recessive. Naturally occurring mutant phenotypes play a role in evolution.

References

1. ^ WESH NBC affiliate news report
2. ^ Picture of Snowflake, a white ape
3. ^ Pictures of albino (and other) reptiles
4. ^ Polydactyly, pictured in cats
5. ^ Memorial University of Newfoundland page with picture, paragraph about antennapedia mutant flies
6. ^ BBC news report World Aquarium in St. Louis auctioning its albino two-headed rat snake. (The snake did not fetch enough money and was ultimately not sold)].
7. ^ International Human Genome Sequencing Consortium (2001). "Initial sequencing and analysis of the human genome.". Nature 409 (6822): 860-921. PMID 11237011.  [1]
8. ^ Robinson Roy (1999), "Genetics for Cat Breeders and Veterinarians", Butterworth Heinemann, ISBN 0-7506-4069-3
9. ^ http://helios.bto.ed.ac.uk/bto/glossary/tuvwxyz.htm

Donate to Wikimedia