Triple X Syndrome

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Classification according to ICD-10
Q97.0 Karyotype 47, XXX
ICD-10 online (WHO version 2019)

The Triple X Syndrome , also known under the synonyms 3 X syndrome , Trisomy X , Triplo-X syndrome and super female syndrome , called the trisomy of the X chromosome in women. The karyotype is: 47, XXX.

Triple X syndrome is one of the poly X syndromes , which are defined by a multiplication of the X chromosome .

root cause

Usually (90%) the polysomy of the X chromosome arises from the fact that the corresponding X chromosome does not diverge during the nucleus division in gametogenesis - especially during the first meiotic division (65%) ( non-disjunction ). This creates a daughter cell without an X chromosome and another daughter cell with two X chromosomes. The fertilization of a daughter cell without an X chromosome with a gamete that contributes an X chromosome leads to a cell in which an X chromosome is missing: a gonosomal monosomy results . The fertilization of a daughter cell with two X chromosomes leads to an excess X chromosome when fertilized with a gamete that contributes another X: A gonosomal trisomy (triple X) results. Little is known about the causes of this, but children of older mothers have a significantly higher risk of developing a trisomy.

frequency

The syndrome occurs with a frequency of 1: 800 to 1: 1000 in girls , although the often inconspicuous symptoms mean that the syndrome may not be diagnosed. Chromosome set 47, XXX is detected in about 0.05 percent of all pregnancies in the unborn child; this does not increase the likelihood of a miscarriage .

Symptoms

Two thirds of all women with triple X syndrome have no physical abnormalities. They are rather tall. Sometimes there is insufficient hormone production by the ovaries in the sense of premature ovarian insufficiency , whereby the resulting so-called secondary amenorrhea can be associated with autoimmune thyroiditis , resulting in restricted fertility and ultimately a premature climacteric . Sometimes there is premature puberty . In around 70 percent of cases, there are learning disabilities (particularly in the area of ​​spoken language) and fine motor skills may be impaired. In rarer cases, the appearance of psychoses is observed. Affected women do not have an increased risk of passing on an increased number of chromosomes to their offspring.

swell

  • Jan Murken: Pocket textbook human genetics: 96 tables . Thieme, Stuttgart a. a. 2006, ISBN 3-13-139297-5 , p. 213.
  • Christian Schaaf: Basic knowledge of human genetics . Springer Berlin, Berlin 2012, ISBN 978-3-642-28906-4 , p. 188.
  • G. Tariverdian, W. Buselmaier: Human Genetics. Springer Verlag, Berlin / Heidelberg 2006, ISBN 3-540-32677-4 , p. 128.
  • C. Schwemmle, M. Ptok: Common syndrome, rarely diagnosed: the triple X syndrome. In: Monthly Pediatrics . Volume 161 (2013), Issue 1, pp. 40-45.

Web links

Individual evidence

  1. ^ Jan Murken: Pocket textbook human genetics: 96 tables . Thieme, Stuttgart a. a. 2006, ISBN 3-13-139297-5 , p. 213.
  2. R. Goswami et al. a .: Prevalence of the triple X syndrome in phenotypically normal women with premature ovarian failure and its association with autoimmune thyroid disorders. In: Fetility and Sterility. Volume 80, Issue 4, pp. 1052-1054 (October 2003)
  3. ^ Christian Schaaf: Basic knowledge of human genetics . Springer Berlin, Berlin 2012, ISBN 978-3-642-28906-4 , p. 188.