What is Klinefelter Syndrome?

About one in 600 newborn boys will have the genetic condition Klinefelter syndrome (sometimes called Klinefelter's or XXY), which means they are born with an extra X chromosome.

This will have happened randomly during the formation of the egg or sperm, or after the baby boy was conceived. The extra chromosome is not inherited.

Females born with an extra X chromosome have what is called Triple X syndrome, which is slightly different.

Adult males with Klinefelter syndrome may not be able to produce enough testosterone, the sex hormone responsible for the development of male characteristics and important for maintaining bone strength, libido and fertility in men.

The features that result from this – such as low energy and sex drive, lack of muscle and too much body fat around the middle – may not be noticeable until after the age of puberty.

Most men with Klinefelter syndrome live independently and have normal lives, jobs and relationships, and will be unaware of their chromosome variation. Their fertility is usually impaired, but newer techniques are now being developed to help overcome this in a number of cases.


Signs & Symptoms

Boys and young adults

  • low self-confidence
  • low energy levels
  • mild learning disabilities such as dyspraxia and dyslexia 
  • difficulty socialising or expressing their feelings
  • Boys may grow more quickly than usual during childhood

Puberty starts at the normal time (11-13 years) with testicle growth as in all boys, but the testicle size does not increase as usual.

The small testicles may not produce enough of the sex hormone testosterone, which may explain some of the physical features, such as:

  • a flabby body with low muscle tone
  • a reduced amount of facial and body hair
  • small, firm testicles and a small penis
  • enlarged breasts (gynaecomastia; affects about two-thirds)
  • reduced calcium in the bones

Adult males

If a man with Klinefelter syndrome was not diagnosed and treated at the time of puberty, he may have some or all of the following features:

  • a low sex drive
  • taller than average for the family 
  • reduced amounts of facial and body hair
  • belly fat and looser muscles
  • enlarged breasts (gynaecomastia) 
  • small testicles and sometimes also a small adult-sized penis
  • anxiety
  • learning difficulties
  • depression
  • intelligence is usually unaffected

Despite these problems, most men with Klinefelter syndrome will have normal independent lives, holding down relationships and jobs.


Support for Klinefelter syndrome

How can we help?

The Practice MK offers an extensive range Counselling and Psychotherapy, often called Talking Therapies to help individuals and their families to manage anxiety and depression. Therapy sessions are delivered by accredited and experienced counsellors and therapists and will provide the opportunity to discuss issues in a safe, understanding and supportive environment.  

Individuals and therapist may wish to discuss current or past issues affecting them, feelings they have around these issues and how these issues affect them and those around them. During sessions, individuals and therapists will look at coping strategies and methods to ensure positive outcomes for all concerned.


Useful information from our Mental Health Collection

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