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Kleinfelter's Syndrome

Genetic Condition Affecting Males


Updated June 10, 2014

Klinefelter's syndrome is a genetic abnormality that affects only males. Named after an American physician, Harry Klinefelter in 1942, Klinefelter's syndrome affects approximately 1 per 1,000 males, making it a very common genetic abnormality.

Chromosomes are genetic material and a person's sex is determined by X and Y chromosomes. Males usually have one X and one Y chromosome (XY). Males with Klinefelter's syndrome have extra X chromosome (XXY).

Althought the extra sex chromosome is common the syndrome itself, its signs and symptoms, are not. Most men with an extra X chromosome never realize they have an additional chromosome.

Causes of Klinefelter's Syndrome
Women who have babies after the age of 35 have a slightly higher incidence of Klinefelter's Syndrome.

Signs Symptoms of Klinefelter's Syndrome

  • Infertility. This symptom is often the one that brings the man with Klinefelter's syndrome to the attention of his doctor. Men with Klinefelter's do not produce sperm

  • Enlarged breasts-gynecomastia

  • Small firm testicles

  • Small penis

  • Sparse facial and body hair

  • Abnormal body proportions. A tendency to long legs and a short trunk.
  • Test for Klinefelter Syndrome
    Genetic tests will show the presence of an extra X chromosome.

    Treatment for Klinefelter's Syndrome
    Klinefelter's syndrome may be identified in adolecense when the testes do not develop when they should. Testosterone therapy can have a number of positive effects although most men with Klienfelter's are never able to father a child. However testosterone can improve sex drive, promote hair growth, increase muscle strength.

    More about Kleinfelter's Syndrome

  • Understanding Klinefelter Syndrome
  • Klinefelter's Syndrome
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