Editing Turner syndrome (section)

=== Inheritance ===
In the majority of cases where monosomy occurs, the X chromosome comes from the mother.<ref name=Monroy2002>{{cite journal | vauthors = Monroy N, López M, Cervantes A, García-Cruz D, Zafra G, Canún S, Zenteno JC, Kofman-Alfaro S | title = Microsatellite analysis in Turner syndrome: parental origin of X chromosomes and possible mechanism of formation of abnormal chromosomes | journal = American Journal of Medical Genetics | volume = 107 | issue = 3 | pages = 181–189 | date = January 2002 | pmid = 11807897 | doi = 10.1002/ajmg.10113 }}</ref> This may be due to a [[nondisjunction]] in the father. [[Meiotic]] errors that lead to the production of X with p arm deletions or abnormal Y chromosomes are also mostly found in the father.<ref name=Uematsu>{{cite journal | vauthors = Uematsu A, Yorifuji T, Muroi J, Kawai M, Mamada M, Kaji M, Yamanaka C, Momoi T, Nakahata T | title = Parental origin of normal X chromosomes in Turner syndrome patients with various karyotypes: implications for the mechanism leading to generation of a 45,X karyotype | journal = American Journal of Medical Genetics | volume = 111 | issue = 2 | pages = 134–139 | date = August 2002 | pmid = 12210339 | doi = 10.1002/ajmg.10506 }}</ref> [[Isochromosome]] X or [[ring chromosome]] X on the other hand are formed equally often by both parents.<ref name=Uematsu /> Overall, the functional X chromosome usually comes from the mother.

In most cases, Turner syndrome is a sporadic event, and for the parents of an individual with Turner syndrome the risk of recurrence is not increased for subsequent pregnancies. Rare exceptions may include the presence of a balanced [[chromosomal translocation|translocation]] of the X chromosome in a parent, or where the mother has 45,X mosaicism restricted to her germ cells.<ref>{{cite journal | vauthors = Frías JL, Davenport ML | title = Health supervision for children with Turner syndrome | journal = Pediatrics | volume = 111 | issue = 3 | pages = 692–702 | date = March 2003 | pmid = 12612263 | doi = 10.1542/peds.111.3.692 | doi-access = free | collaboration = Committee on Genetics Section on Endocrinology }}</ref>