45, X Gonadal Dysgenesis - Turner Syndrome

Overview, Causes, & Risk Factors

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 communication\ \education, including reading, writing, and basic math\ \motor function\ \personal care, such as bathing, dressing, eating, and toileting\ \social skills\ \thinking skills, such as decision making, problem solving, and self-direction\ \working\ ',CAPTION,'Mental Retardation');" onmouseout="return nd();">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.

Symptoms & Signs

What are the signs and symptoms of the condition?

The most common features of Turner syndrome are:

  • short stature
  • failure to develop sexually
  • puffiness of the backs of the hands and feet at birth
  • congenital heart disease
  • low hairline on the back of the neck
  • excess skin or webbing of the neck
  • pigmented mole-like lesions on the skin
  • kidney defects
  • short fourth fingers
  • inability to fully extend the elbows

    • Diagnosis & Tests

    How is the condition diagnosed?

    A healthcare provider may suspect that a newborn has Turner syndrome if the baby is small and has puffy hands and feet. In older females, underdeveloped ovaries may lead her doctor to suspect Turner syndrome. While measurement of certain hormones are useful, chromosome analysis is the definitive diagnostic test.

    Prevention & Expectations

    What can be done to prevent the condition?

    Turner syndrome is caused by a chromosomal abnormality that is present at conception. Therefore, there is no way to prevent Turner syndrome. Genetic counseling is useful for affected individuals and their families.

    What are the long-term effects of the condition?

    Long-term effects can include:

  • infertility
  • diabetes, a disorder characterized by altered levels of sugar in the blood
  • thyroid disease
  • high blood pressure
    • Life span is usually normal.

    What are the risks to others?

    Turner syndrome is not contagious. Since females with Turner syndrome are usually infertile, there is little risk that they will pass the disorder on to any children.

    Treatment & Monitoring

    What are the treatments for the condition?

    Treatments include:

  • estrogen
  • growth hormone
  • anabolic steroids

    • Treatment must be timed carefully to assure maximum growth and normal mental development. Surgery may be necessary to treat whatever birth defects are present. If a learning disability is present, special education may be needed.

    What are the side effects of the treatments?

    If the timing of treatment is not balanced carefully, there may be premature closure of the growth plates of bones, leading to excessively short stature. Aggressive estrogen therapy may cause tenderness of the breasts and lead to high blood pressure.

    What happens after treatment for the condition?

    Treatment for growth can be stopped after adult height is reached. Treatment to stimulate secondary sexual characteristics, such as the breasts, must continue throughout life.

    How is the condition monitored?

    Treatment is monitored by growth measurements, x-rays, and hormone levels.

    Attribution

    Author:Ronald J. Jorgenson, DDS, PhD, FACMG
    Date Written:
    Editor:Smith, Elizabeth, BA
    Edit Date:06/12/00
    Reviewer:Eileen McLaughlin, RN, BSN
    Date Reviewed:05/07/01

    Sources

    Stevenson RE, Hall JG, and Goodman RM: Human Malformations and Related Anomalies. Oxford University Press, 1993