Other Names for this Disease
- Klinefelter's syndrome
- XXY syndrome
What are the signs and symptoms of Klinefelter syndrome?
What causes Klinefelter syndrome?
Is Klinefelter syndrome inherited?
How might Klinefelter syndrome be treated?
The most common symptom of Klinefelter syndrome is infertility. Other symptoms may include:
- Small, firm testicles
- Small penis
- Only a small amount of body hair
- Sexual difficulties
- Enlarged breasts (gynecomastia)
- Tall height
- Abnormal body proportions (long legs, short trunk)
Boys with Klinefelter syndrome may also have learning disabilities and difficulty with speech and language development. They tend to be quiet, sensitive, and unassertive, but personality characteristics vary among males with this condition. 
Because symptoms of Klinefelter syndrome (KS) can sometimes be very mild, many individuals are never diagnosed or treated. The type of therapies available for individuals seeking treatment depends on the type of symptoms present. There are conflicting opinions in some of the literature about when treatment should be started and who should be treated. The earlier in life that KS symptoms are recognized and treated (for example, by early puberty), the more likely it is that the symptoms can be reduced or eliminated. However, although the majority of boys with KS grow up to live as males, some reportedly develop atypical gender identities. For these individuals, certain therapies (such as supplemental testosterone) may not be suitable. Gender identity should be discussed with health care providers before starting treatment.
Management options available to individuals with signs and symptoms of Klinefelter syndrome may include:
- Educational interventions – As children, many individuals with Klinefelter syndrome qualify for special services to help them in school. Teachers can also help by using certain methods in the classroom, such as breaking bigger tasks into small steps.
- Therapeutic options – A variety of therapists, such as physical, speech, occupational, behavioral, mental health, and family therapists, can often help reduce or eliminate some of the symptoms of Klinefelter syndrome such as poor muscle tone, speech and language problems, or low self-confidence.
- Medical management – About half of individuals with KS have low testosterone levels, which may be raised by taking supplemental testosterone. Having a more normal testosterone level can help individuals develop bigger muscles, a deeper voice, and facial and body hair. Many healthcare providers recommend testosterone therapy when a boy reaches puberty. However, not all males with KS benefit from testosterone therapy, and this therapy also may not be suitable for some individuals depending on gender identity. Some individuals may opt to have breast removal or reduction surgery.
- Aksglaede L, Link K, Giwercman A, Jørgensen N, Skakkebaek NE, Juul A. 47,XXY Klinefelter syndrome: clinical characteristics and age-specific recommendations for medical management. Am J Med Genet C Semin Med Genet. February 15, 2013; 163C(1):55-63.
- Klinefelter Syndrome: Condition Information. NICHD. November 30, 2012; http://www.nichd.nih.gov/health/topics/klinefelter/conditioninfo/Pages/Default.aspx. Accessed 1/1/1900.
- Kirmse B. Klinefelter syndrome. MedlinePlus Web site. December 11, 2006; http://www.nlm.nih.gov/medlineplus/ency/article/000382.htm. Accessed 4/1/2008.
- Klinefelter syndrome. Genetics Home Reference (GHR). July 2008; http://ghr.nlm.nih.gov/condition=klinefeltersyndrome. Accessed 12/10/2008.
- Learning about Klinefelter syndrome. National Human Genome Research Institute (NHGRI) Web site. May 27, 2008; http://www.genome.gov/19519068. Accessed 12/10/2008.
- Klinefelter syndrome. Genetics Home Reference (GHR). 2006. Available at: http://ghr.nlm.nih.gov/condition%3Dklinefeltersyndrome.Accessed September 21, 2007..
- What are the treatments for symptoms in Klinefelter syndrome?. NICHD. November 30, 2012; http://www.nichd.nih.gov/health/topics/klinefelter/conditioninfo/Pages/treatments.aspx. Accessed 9/17/2013.
- Klinefelter Syndrome. National Institute of Child Health and Human Development (NICHD) . November 2012; http://www.nichd.nih.gov/health/topics/klinefelter/conditioninfo/Pages/Default.aspx. Accessed 8/21/2013.