Turner syndrome is a genetic disorder caused by the lack of an X chromosome.

What is going on in the body?

Turner syndrome only affects females. Because females with Turner syndrome don't have the normal number of chromosomes, the body's natural balance is upset. This results in underdevelopment of the ovaries, breasts, uterus and vagina. Females with this disorder are infertile.

Women with Turner syndrome are shorter than average, usually under 5' tall. This disorder usually does not cause mental retardation, but some affected females have learning disabilities. They also may have confusion about space and distances.

What are the causes and risks of the condition?

Turner syndrome is caused when a fertilized egg is missing one of the sex chromosomes. Most people have forty-six chromosomes in the nucleus of each cell of their bodies. These chromosomes exist in matched pairs, meaning there are 23 pairs. One of these 23 pairs determines whether a person will be a male or a female. This pair is called the sex chromosome pair. The sex chromosomes are designated by letters. The letter X designates the chromosome associated with being female. The letter Y designates the chromosome associated with being male. Most females have two X chromosomes. Most males have an X chromosome and a Y chromosome.

If the only sex chromosome present is an X, the person will be a female with the Turner syndrome. The scientific designation for this situation is 45,X. Since one of the sex chromosomes is missing in Turner syndrome, the body's natural balance is upset, causing the problems in growth and development described above.

Turner syndrome is seen in 1 in 10,000 live births. It is much more common at conception, however, indicating that most affected fetuses do not survive.