XX man

An XX man is an individual who has a male appearance ( phenotype ) even though he has an XX karyotype ( De la Chapelle syndrome ). This means that both sex chromosomes are X chromosomes , while the Y chromosome , which is normally required for the development of the male phenotype, is missing. The frequency of occurrence is given as 1: 10,000 to 1: 20,000, while Klinefelter's syndrome , which is similar in terms of external features, is about ten times as common. Up to puberty and usually beyond that, there is inconspicuous social gender development . As with the here not present aneuploidy can not here speak of a disease, but only by a hormonally induced specific phenotypic expression.

root cause

Hypothetical development of the syndrome: Through crossing-over during prophase I of meiosis , the SRY moves from the Y to the X chromosome. 2 of the 4 germ cells are affected by this effect.

The cause of this form of sexual differentiation has not yet been conclusively clarified. Among other things, a translocation of the sex determining region of Y (SRY) from the short arm of the Y chromosome to the short arm of the X chromosome is assumed during male meiosis , i.e. when the father produces sperm . The latter gives rise to four male germ cells , one of which contains the modified X chromosome. When this sperm fertilizes an egg, the SRY on the X chromosome leads to the development of testes and other male sexual characteristics via the production of the testicular-determining factor in the embryo . However, since there are ultimately two X chromosomes - the altered paternal and the maternal - the appearance in adolescents and adults essentially corresponds to that of Klinefelter's syndrome , although the gigantic stature that regularly occurs there is not observed. Here as there, azoospermia leads to infertility (infertility, sterility).

diagnosis

The diagnosis is carried out by means of chromosome analysis ( karyogram ) and the molecular genetic evidence of the SRY, usually as part of a clarification if there is a desire to have children. A causal (causal) therapy is not possible.

See also

• Intersex
• XY woman

literature

• J. Eberle, K. Scheiber: The XX-man syndrome. In: Current Urology. 18, 1987, pp. 80-81, doi : 10.1055 / s-2008-1061424 .

Individual evidence

1. ↑ Orpha.net: The portal for rare diseases and orphan drugs: 46, XX testicular disorder of sex development .
2. ↑ T. Wang, JH Liu, J. Yang, J. Chen, ZQ Ye: 46, XX male sex reversal syndrome: a case report and review of the genetic basis. In: Andrologia. Volume 41, 2009. pp. 59-62. doi : 10.1111 / j.1439-0272.2008.00889.x .

This article is about a health issue. It is not used for self-diagnosis and does not replace a diagnosis by a doctor. Please note the information on health issues !