Turner syndrome

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Turner syndrome

Definition:

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Turner syndrome is a genetic condition that occurs only in females. Female cells normally have two X chromosomes. In Turner syndrome, the girl's cells are missing an X chromosome, or part of an X chromosome. There are a variety of signs and symptoms that can result, but the most common are short height, lack of developing ovaries, and infertility.

Alternative Names:
Bonnevie-Ullrich syndrome; Gonadal dysgenesis; Monosomy X
Causes, incidence, and risk factors:

Humans have 46 chromosomes, which contain all of a person?s genes and DNA. Two of these chromosomes, the sex chromosomes, determine a person?s gender. Both of the sex chromosomes in females are called X chromosomes. (This is written as XX.) Males have an X and a Y chromosome (written as XY). The two sex chromosomes help a person develop fertility and the sexual characteristics of their gender.

In Turner syndrome, the girl does not have the usual pair of two complete X chromosomes. The most common scenario is that the girl has only one X chromosome in her cells. Some girls with Turner syndrome do have two X chromosomes, but one of the X chromosomes is incomplete. In another scenario, the girl has some cells in her body with two X chromosomes, but other cells have only one.

Turner syndrome occurs in about 1 out of 2,000 live births.