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Symptoms
By Mayo Clinic staffSigns and symptoms of Klinefelter syndrome vary. In some males, the condition has a noticeable impact on growth or appearance. Klinefelter syndrome can also be linked to learning and language problems in some cases. However, many people with Klinefelter syndrome have few noticeable symptoms, and in many cases the condition goes undiagnosed until adulthood.
Klinefelter syndrome symptoms vary by age:
- Babies with Klinefelter syndrome may have no noticeable signs or symptoms at first. As they get older, they may have weak muscles and take longer to sit up and crawl and may walk later than other infants do.
- Boys and teenagers with Klinefelter syndrome may be taller and have longer legs than do other boys. They may reach puberty later than other adolescents do. When they do reach puberty, they may have less muscular bodies and less facial and body hair than other teens do. They also may have testicles that are smaller and firmer than those of other boys. In some cases, low testosterone levels caused by Klinefelter syndrome can lead to enlarged breast tissue (gynecomastia), weaker bones and lower energy levels. Boys with Klinefelter syndrome may be shy and may not be as assertive as other boys are.
- Men with Klinefelter syndrome are usually normal in appearance, though they may be taller than average. Unless they're treated with testosterone, the men are likely to have weak bones (osteoporosis). Most men with Klinefelter syndrome have normal sexual function but cannot father children. Some men with the condition are able to father children with the help of new treatments.
When to see a doctor
You should see a doctor to rule out Klinefelter syndrome or another health condition if you or your son has:
- Slow development during infancy or boyhood. If your son seems to be developing more slowly than other boys are, see your son's doctor. Some variation in physical and mental development is normal among boys. But it's always best to check with a doctor if you have any concerns. Delays in growth and development can be the first sign of a number of conditions that need treatment — including Klinefelter syndrome. If your son does have Klinefelter syndrome, starting testosterone therapy at the time of the usual onset of puberty can help treat or prevent a number of problems caused by the disorder.
- Male infertility. If you haven't been able to get your partner pregnant after a year of regular, unprotected sex, see a doctor. Chances are it's caused by something other than Klinefelter syndrome, but many men aren't diagnosed with the condition until they realize they're unable to father a child. If you do have Klinefelter syndrome, you'll probably never be able to father a child — but you still may need treatment for the condition.
- Klinefelter syndrome. National Institutes of Health. http://www.nichd.nih.gov/health/topics/klinefelter_syndrome.cfm. Accessed Feb. 19, 2008.
- Klinefelter syndrome. Madison's Foundation. http://www.madisonsfoundation.org/index.php/component/option,com_mpower/diseaseID,195/. Accessed Feb. 19, 2008.
- Lanfranko F, et al. Klinefelter's syndrome. The Lancet. 2004;364(9430):273-283
- Bojesen A, et al. Klinefelter syndrome in clinical practice. Nature Clinical Practice Urology. 2007;4(4):192-193.
- Klinefelter syndrome. U.S. National Library of Medicine. http://ghr.nlm.nih.gov/condition=klinefeltersyndrome. Accessed Feb. 26, 2008.
- Klinefelter (XXY) syndrome. California Department of Developmental Services. http://www.ddhealthinfo.org/coursebuilder/?id=25. Accessed Feb. 19, 2008.
