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{{refimprove|date=September 2009}}
'''X-linked dominant inheritance''', sometimes referred to as '''X-linked dominance''', is a mode of [[genetics|genetic 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]] 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.
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==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 [[gender]] 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.
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===Inheritance===
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In X-linked dominant inheritance, when the mother alone is the [[genetic carrier|carrier]] of a mutated, or defective gene associated with a disease or disorder; she herself will have the disorder. Her children will inherit the disorder as follows:
*Of her daughters and sons: 50% will have the disorder, 50% will be completely unaffected. Children of both genders have an even chance of receiving either of their mother's two X chromosomes, one of which contains the defective gene in question.
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When the father alone is the carrier of a defective gene associated with a disease or disorder, he too will have the disorder. His children will inherit the disorder as follows:
*Of his daughters: 100% will have the disorder, since all of his daughters will receive one copy of his single X chromosome.
*Of his sons: none will have the disorder; sons do not receive an X chromosome from their father.
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If both parents were carriers of a defective gene associated with a disease or disorder, they would both have the disorder. Their children would inherit the disorder as follows:
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Some X-linked dominant conditions such as [[Aicardi Syndrome]] are fatal to boys, therefore only girls with these conditions survive. Similarly, individuals with [[Klinefelter's Syndrome]] are referred to as "47,XXY Males".
==List of
*Vitamin D resistant rickets
*Rett's syndrome
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*Charcot-Marie-Tooth disease<ref name=Neurology>{{cite journal|last=Yiu|first=E.M.|coauthors=N. Geevasinga, G.A. Nicholson, E.R. Fagan, M.M. Ryan, R.A. Ouvrier|title=A retrospective review of X-linked Charcot-Marie-Tooth disease in childhood|journal=Neurology|date=1|year=2011|month=February|volume=76|issue=5|pages=461-466|doi=10.1212/WNL.0b013e31820a0ceb|accessdate=11 May 2012}}</ref>
==
*[[X-linked hypophosphatemia]]
*[[Rett syndrome]]
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{{X-linked disorders}}
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[[it:Ereditarietà eterosomica dominante]]
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