Klinefelter Syndrome – Cause, Signs, Symptoms, & Treatment

Today there is a plethora of genetic disorders in the field of medicine. Klinefelter syndrome is one of the common genetic conditions that is characterized by the development of an extra copy of the X chromosome. Typically, Klinefelter syndrome affects males, especially young boys. However, this condition may often go undiagnosed until the symptoms start to develop during adulthood.

Some of the symptoms of Klinefelter syndrome include small testicles, low production of testosterone, enlarged breast tissue, reduced muscle mass, and facial hair. It is essential to note that not every male affected by Klinefelter syndrome show the same effects.


Most of the time, educative learning programs, support groups, and assisted reproductive procedures may help to manage patients with Klinefelter syndrome. Since it is a genetic disorder, there is no cure for this condition. Let’s read the article to understand the effects of Klinefelter syndrome. Furthermore, we will look at the diagnosis and management of this unique disorder.

What is Klinefelter syndrome?

Klinefelter syndrome is a genetic condition that typically affects males. In this condition, the male is born with an extra copy of the X chromosome in the cells (a chromosome that carries the genetic material of females). (1)

Often, the affected males may develop smaller than normal testicles leading to a dramatic decrease in the production of testosterone in the body. Testosterone is a male hormone that usually stimulates sexual traits like body hair and muscle growth.

Reduced production of testosterone may cause several symptoms. In most cases, the men with Klinefelter syndrome are infertile. The prevalence of Klinefelter syndrome is around one in every 500 or 1000 newborn males. (2)

What causes Klinefelter syndrome?

Generally, humans are born with 23 pairs of chromosomes or 46 chromosomes in the total present in every cell of the body. Two among them are considered as the sex chromosome identified as X and Y.

The females are typically born with two X chromosomes (XX), which results in the formation of female sexual traits such as breasts and uterus. On the other hand, males are usually born with one X and one Y chromosome (XY), leading to the development of male sexual traits such as a penis and testicles.

As mentioned above, Klinefelter syndrome is a genetic disorder in which males are born with an extra copy of the X chromosome. This condition is also known as XXY disorder. One of the risk factors for this condition is pregnant women above 35 years of age. (3)

What are the signs and symptoms of Klinefelter syndrome?

Most of the symptoms of Klinefelter syndrome occur as a result of low testosterone in the body. Therefore, a person with Klinefelter syndrome may experience the symptoms after puberty when the testosterone levels start to develop sexual traits in males.

One of the earliest signs of Klinefelter syndrome is a delay in learning and speaking. Often, a boy with this condition might speak later than his peers.  Some of the common symptoms of Klinefelter syndrome are listed below –

  • Small-sized penis
  • Small and firm testicles
  • Little or no sperm production leading to sterility
  • Enlarged breast tissue, also known as, gynecomastia (4)
  • Reduced hair growth on the face and body
  • Abnormal height
  • Long legs with a short trunk
  • Reduced muscle mass leading to lower strength in the body
  • Lack of energy and sex drive
  • Problems with communicating and reading
  • Problems with social interaction
  • Low self-esteem leading to anxiety and depression
  • Metabolic disorders such as diabetes

In severe cases, the affected male may consist of more than one extra copy of the X chromosome. Such conditions may lead to bone problems, changes in facial features, poor coordination, and difficulty with speech and learning.

How is Klinefelter syndrome diagnosed?

There are a series of diagnostic tests performed to confirm the presence of an extra X chromosome. Some of the diagnostic criteria for Klinefelter syndrome are –

  • Amniocentesis – a small amount of amniotic fluid is drawn and examined
  • Chorionic villus sampling – chorionic villi are tiny finger-like projections that are a part of the placenta. The cells are removed from these projections for laboratory testing
  • Karyotyping – it is a type of blood test that identifies the extra copy of X chromosome (5)
  • Hormone test – the blood and the urine are sampled to check the levels of testosterone

What is the treatment for Klinefelter syndrome?

Typically, there is no cure for this genetic disorder. However, hormone therapy and assisted reproductive procedures can help to manage the symptoms. Usually, the treatment is started as early as possible, preferably during puberty. Some of the treatments for Klinefelter syndrome are as follows –

  • Testosterone replacement therapy – is used to trigger the development of male sexual traits such as deep voice, increased hair growth, muscle mass, size of the penis, and bone strength. This therapy can be taken in the form of a pill, cream, or patch. (6)
  • Speech and language therapy
  • Educational support program to help the boy function at school
  • Occupational therapy to function appropriately at work
  • Behavioral therapy to improve social skills
  • Counseling for people with depression
  • Surgical assistance to remove the breast tissue
  • Assisted reproduction procedures to treat infertility

Take away message

Klinefelter syndrome is one of the unique developmental disabilities that mainly affect males. It is caused by the development of one or more copies of the X chromosome in the cells. Often males affected by this genetic condition experience reduced testosterone production due to the small size of testicles and penis. Female sexual traits may increase, leading to enlarged breast tissue, less hair growth on the face and body, reduced muscle mass, and bone strength.


Additionally, males with Klinefelter syndrome are socially inactive and have problems with learning and communication. Treatment of Klinefelter syndrome includes hormonal therapy, assisted reproduction procedures, and behavioral therapy to better the lives of the person.


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