NOTE: The following information is meant for educational and informational purposes only and is not intended as a tool to diagnosis or treat any medical condition.

Klinefelter Syndrome

What is Klinefelter Syndrome?

Klinefelter syndrome (KS), also known as XXY-Syndrome is a genetic condition that occurs in males who are born with an extra copy of the X chromosome. Klinefelter syndrome can affect different stages of male development, such as physical appearance, language, and social maturity.


Signs and symptoms of Klinefelter syndrome vary by age. Prior to puberty, boys with Klinefelter syndrome may be taller and may have more fat around their abdomen than other boys their age. After puberty, they may have:

  • Smaller genitals
  • Small firm testicles
  • Enlarged breast tissue (gynecomastia)
  • Reduced body and facial hair
  • Less muscle tone
  • Longer legs, wider hips and narrower shoulders compared to other boys
  • Bone weakness
  • Lower sexual interest
  • Reduced energy levels

Young men with Klinefelter syndrome may have language or learning problems. Many are shy and quiet and tend to have difficulty interacting socially. In adult males, infertility is the most symptom.


In addition to a physical examination of the genital area and chest, two other tests are commonly used to diagnose Klinefelter syndrome:

  • Hormone testing: Blood and urine samples are evaluated for abnormal hormone levels
  • Chromosome analysis: A blood sample is taken and analyzed in a lab to check the shape and number of chromosomes


Although there is no cure for Klinefelter syndrome, early treatments can help minimize its effect. The earlier treatment is initiated, the more promising the outcome. Treatments may include:

  • Testosterone replacement therapy
  • Breast tissue removal or gynecomastia reduction surgery
  • Speech and physical therapy
  • Additional education support
  • Fertility treatments

Resources and Support

To learn more about Klinefelter Syndrome visit:

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