One of my best friends deals with this question all the time, at school, at doctors’ offices and even at adoption and foster care support groups. I guess it is rather surprising that more people don’t know about it considering the statistics I found.

“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 from having the extra chromosome-is uncommon. Many men live out their lives without ever even suspecting that they have an additional chromosome.”

If your son is affected by this syndrome it should become apparent by the time you begin potty training if you hadn’t already noticed some deficiency. My friend’s son’s testes are about the size of frozen green peas and she says that his penis hasn’t grown at all since he was first placed with her at eighteen months of age. Other characteristic he displays are lack of body hair and speech and language delays. He isn’t old enough yet at eight years old to know if he will develop breast and he isn’t currently tall for his age or overweight.

“In addition to occasional breast enlargement, lack of facial and body hair, and a rounded body type, XXY males 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.

A far more serious symptom, however, is one that is not always readily apparent. Although they are not mentally retarded, most XXY males have some degree of language impairment. As children, they often learn to speak much later than do other children and may have difficulty learning to read and write. And while they eventually do learn to speak and converse normally, the majority tends to have some degree of difficulty with language throughout their lives. If untreated, this language impairment can lead to school failure and its attendant loss of self esteem. ”

My friend’s son’s diagnosis is complicated by the fact that he also has FAS and Autism. The fact that he is short may be because of the FAS. The endocrinologist felt that he met the criteria to give him growth hormone injections; however my friend declined because the Klinefelter’s syndrome may at some point cause abnormal growth. He has participated with early-on services and continues to participate with services for the learning disabled, speech and physical therapy.


For more information, see this guide to Understanding Klinefelter Syndrome.

Elsewhere on the Web
Klinefelter Syndrome Support Groups

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