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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/12/01 13:20:47」(JST)

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Neomorph redirects here. It is also one of the post-human types of persons in the novel Eon by Greg Bear.

Hermann J. Muller (1890–1967), who was a 1946 Nobel Prize winner, coined the terms amorph, hypomorph, hypermorph, antimorph and neomorph to classify mutations based on their behaviour in various genetic situations.^[1] These classifications are still widely used in Drosophila genetics to describe mutations. For a more general description of mutations, see mutation, and for a discussion of allele interactions, see dominance relationship.

Key: In the following sections, alleles are referred to as +=wildtype, m=mutant, Df=gene deletion, Dp=gene duplication. Phenotypes are compared with '>', meaning 'phenotype is more severe than'

Loss of function

Amorph

Amorphic describes a mutation that causes complete loss of gene function.^[1] Amorph is sometimes used interchangeably with "genetic null". An amorphic mutation might cause complete loss of protein function by disrupting translation ("protein null") and/or preventing transcription ("RNA null").

An amorphic allele elicits the same phenotype when homozygous and when heterozygous to a chromosomal deletion or deficiency that disrupts the same gene.^[2] This relationship can be represented as follows:

m/m = m/Df

An amorphic allele is commonly recessive to its wildtype counterpart. It is possible for an amorph to be dominant if the gene in question is required in two copies to elicit a normal phenotype (i.e. haploinsufficient).

Hypomorph

Hypomorphic describes a mutation that causes a partial loss of gene function.^[1] A hypomorph is a reduction in gene function through reduced (protein, RNA) expression or reduced functional performance, but not a complete loss.

The phenotype of a hypomorph is more severe in trans to a deletion allele than when homozygous.^[2]

m/m > m/Df

Hypomorphs are usually recessive, but occasional alleles are dominant due to haploinsufficiency.

Gain of function

Hypermorph

A hypermorphic mutation causes an increase in normal gene function.^[1] Hypermorphic alleles are gain of function alleles. A hypermorph can result from an increase in gene dose (a gene duplication), from increased mRNA or protein expression, or constitutive protein activity.

The phenotype of a hypermorph is worsened by increasing the wildtype gene dose, and is reduced by lowering wildtype gene dose.^[2]

m/Dp > m/+ > m/Df

Antimorph

Antimorphs are dominant mutations that act in opposition to normal gene activity.^[1] Antimorphs are also called dominant negative mutations.

Increasing wildtype gene function reduces the phenotypic severity of an antimorph, so the phenotype of an antimorph is worse when heterozygous than when in trans to a gene duplication.^[2]

m/+ > m/Dp

An antimorphic mutation might affect the function of a protein that acts as a dimer so that a dimer consisting of one normal and one mutated protein is no longer functional.

Neomorph

A neomorphic mutation causes a dominant gain of gene function that is different from the normal function.^[1] A neomorphic mutation can cause ectopic mRNA or protein expression, or new protein functions from altered protein structure.

Changing wildtype gene dose has no effect on the phenotype of a neomorph.^[2]

m/Df = m/+ = m/Dp

References

^ ^a ^b ^c ^d ^e ^f Muller, H. J. 1932. Further studies on the nature and causes of gene mutations. Proceedings of the 6th International Congress of Genetics, pp. 213–255.
^ ^a ^b ^c ^d ^e Wilkie, A. O. 1994. The molecular basis of genetic dominance. Journal of Medical Genetics 31: 89-98. [1]

English Journal

Revisiting PC1/3 Mutants: Dominant-Negative Effect of Endoplasmic Reticulum-Retained Mutants.

Blanco EH1, Ramos-Molina B1, Lindberg I1.
Endocrinology.Endocrinology.2015 Oct;156(10):3625-37. doi: 10.1210/en.2015-1068. Epub 2015 Jul 24.
Prohormone convertase 1/3 (PC1/3), encoded by the gene PCSK1, is critical for peptide hormone synthesis. An increasing number of studies have shown that inactivating mutations in PCSK1 are correlated with endocrine pathologies ranging from intestinal dysfunction to morbid obesity, whereas the common
PMID 26207343

Role of the planar cell polarity gene Protein tyrosine kinase 7 in neural tube defects in humans.

Wang M1, De Marco P2, Merello E2, Drapeau P3,4, Capra V2, Kibar Z1,3.
Birth defects research. Part A, Clinical and molecular teratology.Birth Defects Res A Clin Mol Teratol.2015 Sep 14. doi: 10.1002/bdra.23422. [Epub ahead of print]
BACKGROUND: Neural tube defects (NTDs) are among the most common congenital defects affecting approximately 1 in 1000 live births in North America. Their etiology is complex including environmental and genetic factors. Defects in the planar cell polarity (PCP) signaling pathway have been strongly as
PMID 26368655

TP53: an oncogene in disguise.

Soussi T1, Wiman KG2.
Cell death and differentiation.Cell Death Differ.2015 Aug;22(8):1239-49. doi: 10.1038/cdd.2015.53. Epub 2015 May 29.
The standard classification used to define the various cancer genes confines tumor protein p53 (TP53) to the role of a tumor suppressor gene. However, it is now an indisputable fact that many p53 mutants act as oncogenic proteins. This statement is based on multiple arguments including the mutation
PMID 26024390

Japanese Journal

Shape Optimization to Improve Impact Energy Absorption Ability of Truss Core Panel

,
Journal of Computational Science and Technology 5(1), 1-12, 2011
… A commercial preprocessor HyperMorph is used for morphing, explicit FEM software LS-DYNA is used to solve crash analysis and LS-OPT is used to handle multiple jobs and optimization process. …
NAID 130000428789

トラスコアパネルの衝撃エネルギー吸収性能向上のための形状最適化

戸倉直,萩原一郎
日本機械学會論文集. A編 76(765), 564-572, 2010-05-25
… A commercial preprocessor HyperMorph is used for morphing, explicit FEM software LS-DYNA is used to solve crash analysis and LS-OPT is used to handle multiple jobs and optimization process. …
NAID 110007619414