Alternative Names monosomy X, Ullrich-Turner syndrome, 45,X gonadal dysgenesis
Definition 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 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
What are the causes and risks of the condition? Turner syndrome is caused when a fertilised 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 foetuses do not survive.
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 counselling is useful for affected individuals and their families.
How is the condition diagnosed? A doctor 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.
What are the long-term effects of the condition? Long-term effects can include:
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.
What are the treatments for the condition? Treatments include:
oestrogen
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 oestrogen 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.
Author: Ronald J. Jorgenson, DDS, PhD, FACMG Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
