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Diseases

Genetic and Rare Diseases Information Center (GARD)

Turner syndrome


Other Names for this Disease
  • Ullrich-Turner syndrome
  • Bonnevie-Ulrich syndrome
  • 45, X Syndrome
  • Chromosome X Monosomy X
  • Gonadal Dysgenesis (45,X)
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Cause

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What causes Turner syndrome?

Turner syndrome is caused by partial or complete loss of one of the X chromosomes in cells of females. Females without Turner syndrome have 2 full X chromosome in all of their cells (and males have one X chromosome and one Y chromosome). The missing genetic material affects development before and after birth.

Most females with Turner syndrome are missing a full X chromosome in all of their cells (also called monosomy X). This form results from a random error in an egg or sperm cell prior to conception.

Some females with Turner syndrome have two X chromosomes, but one of them is missing a piece (has a deletion). Depending on the specific gene(s) that are missing, the features of Turner syndrome may result. A deletion may occur sporadically (not inherited) or may be inherited from a parent.

Mosaic Turner syndrome (when some cells have one X chromosome and some have two sex chromosomes) is caused by a random error in early fetal development (shortly after conception).

It is still unclear exactly which genes on the X chromosome are associated with each feature of Turner syndrome. It is known that the SHOX gene on the X chromosome is important for growth and bone development. A missing copy of this gene is thought to result in the short stature and skeletal abnormalities in many affected women.[1]
Last updated: 1/11/2016

References
  1. Turner syndrome. Genetics Home Reference. January, 2012; http://ghr.nlm.nih.gov/condition/turner-syndrome.


Other Names for this Disease
  • Ullrich-Turner syndrome
  • Bonnevie-Ulrich syndrome
  • 45, X Syndrome
  • Chromosome X Monosomy X
  • Gonadal Dysgenesis (45,X)
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.