The Robinson Library >> Medicine >> Diseases of the Genitourinary System

Klinefelter Syndrome

a group of symptoms found in some men with an extra X chromosome

In 1942, Dr. Henry Klinefelter and some of his co-workers at Massachusetts General Hospital in Boston published a report about nine men with enlarged breasts, sparse facial and body hair, small testes, and an inability to produce sperm, and it was this cluster of symptoms that became known as Klinefelter Syndrome. By the late 1950's it had been learned that many of the men who exhibited these symptoms had an extra X chromosome in some of their cells. It has since been found that at least one in every 500 males has an extra X chromosome in some of their cells, but that most of them never present any symptoms. Since every man who exhibits symptoms of Klinefelter Syndrome has an extra X chromosome, but not every male who has the extra chromosome exhibits symptoms, doctors now prefer to use the term XXY Condition rather than Klinefelter Syndrome.

The type and degree of symptoms displayed in men with the XXY Condition depends on how many XXY cells the man has, how much testosterone his body is producing, and his age when the condition was diagnosed. Late physical development as a baby is one of the earliest presentations of the condition. As the child grows he may be taller than his peers but have less muscle control and coordination. In puberty he may have less facial and body hair and be broader in the hips than other boys. Enlarged breasts (gynecomastia), weaker bones and less energy are experienced in teens, and adult men with XXY are often taller than their peers. Most men with XXY are able to enjoy a normal sex life, but 95 to 99 percent of them are infertile. In fact, the condition is often not even discovered until a man undergoes genetic testing in order to determine the cause of his sterility.

Children with XXY may also have trouble learning to talk, using language to express their thoughts and needs, and processing what they hear. These problems generally resolve themselves as the child ages, but adult men may continue to have trouble with tasks that involve reading and writing. Pronounced shyness, lack of self-confidence, and a tendency to more helpful and obedient than other children are also possible early symptoms of XXY.

The only way to conclusively determine if a child or adult's symptoms are caused by XXY is through genetic testing. There is no cure, but the earlier the condition is found the easier it is to treat the symptoms. If discovered early in life most of the language-related and social development symptoms can be treated with therapies directed at those issues, as can the problems with coordination and muscle control. Physical symptoms such as gynecomastia, reduced facial hair, and broadened hips can usually be alleviated by testosterone replacement therapy.

American Association for Klinefelter Syndrome Information and Support


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The Robinson Library >> Medicine >> Diseases of the Genitourinary System

This page was last updated on 07/28/2017.