Editing Mutation (section)

=== By effect on function ===
A mutation becomes an effect on function mutation when the exactitude of functions between a mutated protein and its direct interactor undergoes change. The interactors can be other proteins, molecules, nucleic acids, etc. There are many mutations that fall under the category of by effect on function, but depending on the specificity of the change the mutations listed below will occur.<ref>{{cite journal | vauthors = Reva B, Antipin Y, Sander C | title = Predicting the functional impact of protein mutations: application to cancer genomics | journal = Nucleic Acids Research | volume = 39 | issue = 17 | pages = e118 | date = September 2011 | pmid = 21727090 | pmc = 3177186 | doi = 10.1093/nar/gkr407 }}</ref>
* Loss-of-function mutations, also called inactivating mutations, result in the gene product having less or no function (being partially or wholly inactivated). When the allele has a complete loss of function ([[null allele]]), it is often called an [[Amorph (gene)|amorph]] or amorphic mutation in [[Muller's morphs]] schema. Phenotypes associated with such mutations are most often [[Dominance (genetics)|recessive]]. Exceptions are when the organism is [[Ploidy#Haploid and monoploid|haploid]], or when the reduced dosage of a normal gene product is not enough for a normal phenotype (this is called [[haploinsufficiency]]). A disease that is caused by a loss-of-function mutation is Gitelman syndrome and cystic fibrosis.<ref>{{cite journal | vauthors = Housden BE, Muhar M, Gemberling M, Gersbach CA, Stainier DY, Seydoux G, Mohr SE, Zuber J, Perrimon N | display-authors = 6 | title = Loss-of-function genetic tools for animal models: cross-species and cross-platform differences | journal = Nature Reviews. Genetics | volume = 18 | issue = 1 | pages = 24–40 | date = January 2017 | pmid = 27795562 | pmc = 5206767 | doi = 10.1038/nrg.2016.118 }}</ref>
* Gain-of-function mutations also called activating mutations, change the gene product such that its effect gets stronger (enhanced activation) or even is superseded by a different and abnormal function. When the new allele is created, a [[Zygosity#Heterozygous|heterozygote]] containing the newly created allele as well as the original will express the new allele; genetically this defines the mutations as [[Dominance (genetics)|dominant]] phenotypes. Several of Muller's morphs correspond to the gain of function, including hypermorph (increased gene expression) and neomorph (novel function).
* Dominant negative mutations (also called anti-morphic mutations) have an altered gene product that acts antagonistically to the wild-type allele. These mutations usually result in an altered molecular function (often inactive) and are characterized by a dominant or [[Dominance (genetics)#Incomplete dominance|semi-dominant]] phenotype. In humans, dominant negative mutations have been implicated in cancer (e.g., mutations in genes [[p53]], [[Ataxia telangiectasia mutated|ATM]], [[CEBPA]], and [[Peroxisome proliferator-activated receptor gamma|PPARgamma]]). [[Marfan syndrome]] is caused by mutations in the [[FBN1]] gene, located on [[Chromosome 15 (human)|chromosome 15]], which encodes fibrillin-1, a [[glycoprotein]] component of the [[extracellular matrix]]. Marfan syndrome is also an example of dominant negative mutation and haploinsufficiency.
* Lethal mutations result in rapid organismal death when occurring during development and cause significant reductions of life expectancy for developed organisms. An example of a disease that is caused by a dominant lethal mutation is [[Huntington's disease]].
* Null mutations, also known as Amorphic mutations, are a form of loss-of-function mutations that completely prohibit the gene's function. The mutation leads to a complete loss of operation at the phenotypic level, also causing no gene product to be formed. [[Atopic dermatitis|Atopic eczema]] and dermatitis syndrome are common diseases caused by a null mutation of the gene that activates filaggrin.
* Suppressor mutations are a type of mutation that causes the double mutation to appear normally. In suppressor mutations the phenotypic activity of a different mutation is completely suppressed, thus causing the double mutation to look normal. There are two types of suppressor mutations, there are [[Epistasis|intragenic]] and extragenic suppressor mutations. Intragenic mutations occur in the gene where the first mutation occurs, while extragenic mutations occur in the gene that interacts with the product of the first mutation. A common disease that results from this type of mutation is [[Alzheimer's disease]].<ref>{{cite journal | vauthors = Eggertsson G, Adelberg EA | title = Map positions and specificities of suppressor mutations in Escherichia coli K-12 | journal = Genetics | volume = 52 | issue = 2 | pages = 319–340 | date = August 1965 | pmid = 5324068 | pmc = 1210853 | doi = 10.1093/genetics/52.2.319 }}</ref>
* Neomorphic mutations are a part of the gain-of-function mutations and are characterized by the control of new protein product synthesis. The newly synthesized gene normally contains a novel gene expression or molecular function. The result of the neomorphic mutation is the gene where the mutation occurs has a complete change in function.<ref>{{cite journal | vauthors = Takiar V, Ip CK, Gao M, Mills GB, Cheung LW | title = Neomorphic mutations create therapeutic challenges in cancer | journal = Oncogene | volume = 36 | issue = 12 | pages = 1607–1618 | date = March 2017 | pmid = 27841866 | pmc = 6609160 | doi = 10.1038/onc.2016.312 }}</ref>
* A back mutation or reversion is a point mutation that restores the original sequence and hence the original phenotype.<ref>{{cite journal | vauthors = Ellis NA, Ciocci S, German J | s2cid = 22290041 | title = Back mutation can produce phenotype reversion in Bloom syndrome somatic cells | journal = Human Genetics | volume = 108 | issue = 2 | pages = 167–73 | date = February 2001 | pmid = 11281456 | doi = 10.1007/s004390000447 }}</ref>