X-linked dominant inheritance: Difference between revisions

Revision as of 22:01, 21 January 2020

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[[File:X-linked dominant.svg|thumb|upright=1.75|X-linked dominant inheritance]]

'''X-linked dominant inheritance''', sometimes referred to as '''X-linked dominance''', is a mode of [[geneticsGenetics|genetic]] [[Heredity|inheritance]] by which a [[dominant gene]] is carried on the [[X chromosome]]. As an inheritance pattern, it is less common than the [[X-linked recessive inheritance|X-linked recessive]] type. In medicine, X-linked dominant inheritance indicates that a gene responsible for a [[genetic disorder]] is located on the X chromosome, and only one copy of the [[allele]] is sufficient to cause the disorder when inherited from a parent who has the disorder. In this case, someone who [[Gene expression|expresses]] an X-linked dominant allele will exhibit the disorder and be considered affected.

X-linked dominant traits do not necessarily affect males more than females (unlike [[X-linked recessive]] traits). The exact pattern of inheritance varies, depending on whether the father or the mother has the trait of interest. All fathers that are affected by an X-linked dominant disorder will have affected daughters but not affected sons. However, if the mother is also affected then sons will have a chance of being affected, depending on whether a dominant or recessive X chromosome is passed on. When the son is affected, the mother will always be affected.

Some scholars have suggested discontinuing the terms dominant and recessive when referring to X-linked inheritance due to the multiple mechanisms that can result in the expression of X-linked traits in females, which include cell autonomous expression, [[skewed X-inactivation]], clonal expansion and [[somatic mosaicism]].<ref name=pmid15316978>{{cite journal | vauthors = Dobyns WB, Filauro A, Tomson BN, Chan AS, Ho AW, Ting NT, Oosterwijk JC, Ober C | title = Inheritance of most X-linked traits is not dominant or recessive, just X-linked | journal = American Journal of Medical Genetics. Part A | volume = 129A | issue = 2 | pages = 136–43 | date = August 2004 | pmid = 15316978 | doi = 10.1002/ajmg.a.30123 }}</ref>

==Genetics==

As the X chromosome is one of the [[sex chromosome]]s (the other being the [[Y chromosome]]), X-linked inheritance is determined by the [[sex]] of the parent carrying a specific gene and can often seem complex. This is due to the fact that, typically, [[female]]s have two copies of the X-chromosome, while [[male]]s have only one copy. The difference between [[Dominance (genetics)#Dominant trait|dominant]] and [[Dominance (genetics)#Recessive|recessive]] inheritance patterns also plays a role in determining the chances of a child inheriting an X-linked disorder from their parentage.{{fact|date=January 2018}}

As the X chromosome is one of the [[sex chromosome]]s (the other being the [[Y chromosome]]), X-linked

inheritance is determined by the [[sex]] of the parent carrying a specific gene and can often seem complex. This is due to the fact that, typically, [[female]]s have two copies of the X-chromosome, while [[male]]s have only one copy. The difference between [[Dominance (genetics)#Dominant trait|dominant]] and [[Dominance (genetics)#Recessive|recessive]] inheritance patterns also plays a role in determining the chances of a child inheriting an X-linked disorder from their parentage.{{fact|date=January 2018}}

Males can only get an X chromosome from their mother whilst females get an X chromosome from both parents. As a result, females tend to show higher prevalence of X-linked dominant disorders because they have more of a chance to inherit a faulty X chromosome.{{fact|date=January 2018}}

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Some X-linked dominant conditions such as [[Aicardi syndrome]] are fatal to boys, therefore only girls with these conditions survive, or boys with [[Klinefelter's syndrome]] (and hence have more than one X chromosome).

SomeA few scholars have suggested discontinuing the use of the terms ''dominant'' and ''recessive'' when referring to X-linked inheritance, duestating tothat the multiplehighly mechanisms that can result in thevariable expressionpenetrance of X-linked traits in females, whichas includea cellresult autonomousof expression,mechanisms such as [[skewed X-inactivation]], clonal expansion andor [[somatic mosaicism]] is difficult to reconcile with standard definitions of dominance and recessiveness.<ref name="pmid15316978">{{cite journal | vauthors = Dobyns WB, Filauro A, Tomson BN, Chan AS, Ho AW, Ting NT, Oosterwijk JC, Ober C |date=August 2004|title = Inheritance of most X-linked traits is not dominant or recessive, just X-linked | journal = American Journal of Medical Genetics. Part A | volume = 129A | issue = 2 | pages = 136–43 | date = August 2004 | pmid = 15316978 | doi = 10.1002/ajmg.a.30123 |pmid=15316978}}</ref>

==List of dominant X-linked diseases==

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*[[Rett syndrome]] (95% of cases are due to sporadic mutations)

*Most cases of [[Alport syndrome]]<ref name=pmid14514738>{{cite journal | vauthors = Jais JP, Knebelmann B, Giatras I, De Marchi M, Rizzoni G, Renieri A, Weber M, Gross O, Netzer KO, Flinter F, Pirson Y, Dahan K, Wieslander J, Persson U, Tryggvason K, Martin P, Hertz JM, Schröder C, Sanak M, Carvalho MF, Saus J, Antignac C, Smeets H, Gubler MC | display-authors = 6 | title = X-linked Alport syndrome: natural history and genotype-phenotype correlations in girls and women belonging to 195 families: a "European Community Alport Syndrome Concerted Action" study | journal = Journal of the American Society of Nephrology | volume = 14 | issue = 10 | pages = 2603–10 | date = October 2003 | pmid = 14514738 | doi = 10.1097/01.ASN.0000090034.71205.74 }}</ref>

*[[Incontinentia pigmenti]]<ref>{{cite web | url = http://dermnetnz.org/systemic/incontinentia-pigmenti.html | title = Incontinentia pigmenti | first = Vanessa | last = Ngan | name-list-format = vanc | publisher = DermNet NZ | date = 2005 }}</ref><ref>{{EMedicine|article|1114205|Incontinentia Pigmenti}}</ref>

*[[Giuffrè–Tsukahara syndrome]]<ref name=pmid20635354>{{cite journal | vauthors = Dalal AB, Sarkar A, Priya TP, Nandineni MR | title = Giuffrè-Tsukahara syndrome: Evidence for X-linked dominant inheritance and review | journal = American Journal of Medical Genetics. Part A | volume = 152A | issue = 8 | pages = 2057–60 | date = August 2010 | pmid = 20635354 | doi = 10.1002/ajmg.a.33505 }}</ref>

*[[Goltz syndrome]]

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== See also ==

*[[X-linked hypophosphatemia]]

*[[Rett syndrome]]

*[[Sex linkage]]

*[[Incontinentia pigmenti]]<ref>{{EMedicine|article|1114205|Incontinentia Pigmenti}}</ref>

*[[X-linked recessive inheritance]]