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Klinefelter Syndrome

Klinefelter Syndrome - Symptoms

What are the features of KS?

KS does not usually cause any obvious symptoms early in childhood, and many boys and men often do not realise they have KS until they go through puberty. In these instances, puberty may be late or incomplete. Sometimes, KS may only be diagnosed in adulthood due to infertility.

The features of KS can vary and it is important to note that not all the features described will be seen in your child.

Most boys with KS can expect to live long and healthy lives.

The typical features of KS in an adult (if untreated) are:

  • Growth. A tall and thin body with disproportionate long arms and legs.
  • Physical features. Breast tissue development (gynaecomastia) and female pattern of fat distribution. Reduced facial and body hair.
  • Small testicles. This feature is present in most people with KS.


Children and adolescents with KS may experience:

  • Learning difficulties  
    • Delayed motor development
    • Difficulties with speech and reading
    • Poor muscle tone
    • Lower attention span
  • Behavioural problems


In adulthood, in addition to the main typical features, untreated adults may have:

  • Hypogonadism. Individuals with KS often have this condition where men are unable to produce enough of the male hormone, testosterone, for the body’s needs.

    Testosterone is important for normal reproductive and sexual function, and physical changes that happen during male puberty such as development of the penis and testes, and facial and body hair. It also helps the growth of bone and muscles.

    Hence, men with KS can have underdeveloped testes, low libido (sex drive), infertility and osteoporosis (thinning of the bones).

    Almost all men with KS will be infertile (sterile), which means they will be unable to father a child without medical help.

  • Physical features. A physique which is less muscular than other men.
  • Intelligence. Most men with KS have normal intelligence, though some may have their intelligence affected.
  • Anxiety and depression

The typical features of Klinefelter Syndrome in an adult (if untreated)


Other medical concerns

The following problems can also be seen in individuals with KS, and need to be monitored for and treated if present:

  • Cardiovascular diseases such as ischaemic heart disease, peripheral vascular disease and pulmonary embolism
  • Metabolic syndromes such as dyslipidaemia and diabetes mellitus
  • Breast cancer
  • Thromboembolism (blood clots in blood vessels)
  • Autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis and Sjogren’s syndrome


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Klinefelter Syndrome - Preparing for surgery

Klinefelter Syndrome - Post-surgery care

The information provided is not intended as medical advice. Terms of use. Information provided by SingHealth