Klinefelter's Syndrome

KLINEFELTER'S SYNDROME
Klinefelter's syndrome is a condition caused by a chromosomal abnormality in males; sufferers have a pair of X chromosomes instead of just one. The XXY chromosome arrangement is a common genetic abnormality, occurring as frequently as 1 in 1,000 male births, but the symptoms that may result from having the extra chromosome is less common. Because of this extra chromosome,individuals with the abnormality are usually referred to as "XXY Males" rather than as "suffering from Klinefelter's syndrome."

In mammals with more than one X chromosome, the genes on all but one X chromosome are barred from being expressed. This happens in XXY males as well as XX females. A few genes, however, have corresponding genes on the Y chromosome and are not barred. These triploidgenes in XXY males may be responsible for the symptoms of Klinefelter's syndrome.

In adults, the syndrome is characterised by gynecomastia (enlarged breasts), a rounded body type with abnormal body proportions, sparse facial and body hair, small testes, and an inability to produce sperm. Most XXY males have some degree of language impairment as well. The syndrome is associated with an increasedrisk of breast cancer, pulmonary disease, varicose veins, and osteoporosis.
The condition was identified in 1942 by Dr. Harry Klinefelter in Boston. The cause was not found until the 1950s; the condition is incurable, but its symptoms can be treated in a number of ways, including testosterone treatment and other therapies.

What is Klinefelter's Syndrome?

In 1942, Dr. Harry Klinefelter and hiscoworkers at the Massachusetts General Hospital in Boston published a report about nine men who had enlarged breasts, sparse facial and body hair, small testes, and an inability to produce sperm.
By the late 1950s, researchers discovered that men with Klinefelter syndrome, as this group of symptoms came to be called, had an extra sex chromosome, XXY instead of the usual male arrangement, XY.(For a more complete explanation of the role this extra chromosome plays, see the accompanying section, "Chromosomes and Klinefelter syndrome.")
In the early 1970s, researchers around the world sought to identify males having the extra chromosome by screening large numbers of newborn babies. One of the largest of these studies, sponsored by the National Institute of Child Health and HumanDevelopment (NICHD), checked the chromosomes of more than 40,000 infants.
Based on these studies, the XXY chromosome arrangement appears to be one of the most common genetic abnormalities known, occurring as frequently as 1 in 500 to 1 in 1,000 male births. Although the syndrome's cause, an extra sex chromosome, is widespread, the syndrome itself-the set of symptoms and characteristics that may result fromhaving the extra chromosome-is uncommon. Many men live out their lives without ever even suspecting that they have an additional chromosome.
" I never refer to newborn babies as having Klinefelter's, because they don't have a syndrome," said Arthur Robinson, M.D., a pediatrician at the University of Colorado Medical School in Denver and the director of the NICHD-sponsored study of XXY males."Presumably, some of them will grow up to develop the syndrome Dr. Klinefelter described, but a lot of them won't."
For this reason, the term "Klinefelter syndrome" has fallen out of favor with medical researchers. Most prefer to describe men and boys having the extra chromosome as "XXY males."
In addition to occasional breast enlargement, lack of facial and body hair, and a rounded body type, XXYmales are more likely than other males to be overweight, and tend to be taller than their fathers and brothers.
For the most part, these symptoms are treatable. Surgery, when necessary, can reduce breast size. Regular injections of the male hormone testosterone, beginning at puberty, can promote strength and facial hair growth-as well as bring about a more muscular body type.
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