Genetics Home > Cause of Turner Syndrome

A condition that only affects females, Turner syndrome is caused by the absence (complete or partial) of one of the two X chromosomes. Researchers have not yet determined which genes on the X chromosome cause most signs and symptoms of Turner syndrome.

An Introduction to the Cause of Turner Syndrome

Turner syndrome is a condition that is present at birth and only affects females. It can cause several different symptoms, from minor cosmetic issues to major heart defects. Almost all women with this condition have short stature and loss of ovarian function. The cause of Turner syndrome is the complete or partial absence of one of the two X chromosomes (sex chromosomes).

Understanding the Sex Chromosomes

Humans normally have a total of 46 chromosomes (which are tiny, DNA-containing elements) that are present in every cell of the body. DNA encodes genes, which specify all the proteins that make up the body and control its functions.
In humans, there are 23 pairs of chromosomes in cells. One pair is inherited from each parent. Each cell contains 22 pairs of chromosomes called autosomes that are the same in males and females. The remaining pair of chromosomes, the X and Y chromosomes, are not shaped similarly, and thus are not matched in the same way as the autosomes.
The X and Y chromosomes are called sex chromosomes. They are responsible for the difference in development between males and females. A Y chromosome contains genes responsible for testis development, and the presence of an X chromosome paired with a Y chromosome will determine male development. On the other hand, two X chromosomes are required for normal ovarian development in females.
Turner syndrome results when a female's cells have one normal X chromosome and the other sex chromosome is missing or altered. The missing genetic material affects development and causes the characteristic Turner syndrome features.
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Last reviewed by: Arthur Schoenstadt, MD
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