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Klinefelter Syndrome

Klinefelter syndrome, also known as XXY syndrome, is a genetic condition that occurs when males have an extra X chromosome in most of their cells. Klinefelter syndrome occurs in 1/500 – 1/1000 male births.  It typically happens by chance and does not run in families.  The most common feature is infertility.

Symptoms

• Tall stature
• Delayed motor and language skills
• Learning disabilities
• Small testes, low testosterone
• Infertility due to low or absent sperm production
• Breast development (due to reduced testosterone)

Causes/Risk Factors

• Increasing maternal age

Genetic Test/Carrier Screen

The following genetic tests may be appropriate based on your personal and/or family history.

• Blood chromosome analysis
• Prenatal diagnostic testing for chromosome abnormalities
  
  • Chorionic villus sampling (CVS)
  • Amniocentesis

See our pre-conception and prenatal services

Schedule an Appointment

To speak with a board-certified genetic counselor about your risks for this disease:

• Schedule genetic counseling appointment online
• Or call 1-800-975-4819
• Send email

Learn More

NIH Genetics Home Reference Page

MedlinePlus

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