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Klinefelter syndrome


Disease: Klinefelter syndrome Klinefelter syndrome
Category: Genetic Diseases

Disease Definition:

One of the most common genetic conditions that affect males is klinefelter syndrome, which is usually the result of an extra copy of the X chromosome in each cell. Between 1 in 500 and 1 in 1,000 men are affected by this syndrome.


Usually, the effects of this syndrome vary from one person to another. Boys who are born with this syndrome have low levels of the sex hormone testosterone because this condition could affect testicular growth, which could result in reduced muscle growth, gynecomastia (enlarged breast tissue) and reduced body and facial hair. In some cases, this syndrome could cause learning and social difficulties during childhood and adolescence.


This syndrome is usually not diagnosed until adulthood. However, treatment could help prevent or treat problems caused by the condition in case it has been diagnosed with a genetic test before birth or during childhood. Although new procedures are making it possible for men with this syndrome to father children, however, most men with Klinedelter syndrome are infertile.

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Symptoms, Causes


Klinefelter syndrome has been linked to learning and language problems in some cases. The signs and symptoms of this syndrome vary. It has a noticeable impact on growth or appearance in some males. Most of the time, this condition goes undiagnosed until adulthood, and many people with this syndrome have only a few noticeable symptoms.


The signs and symptoms of klinefelter syndrome vary by age:


This syndrome may not show any noticeable signs and syndromes at first. However, as they get older, they may walk later than other infants do, and they may have weak muscles and take longer to sit up and crawl.

Boys and teenagers:

This syndrome could cause boys and teenagers to be taller and have longer legs than others. They may reach puberty later than other adolescents do, and when they reach it, they may have less muscular bodies and less facial and body hair. Their testicles may also be smaller and firmer. Sometimes, weaker bones, lower energy levels and gynecomastia may be caused due to the low testosterone levels caused by klinefelter syndrome. Boys with this syndrome may be less assertive than others, and they may be shy.


Although men with klinefelter syndrome may be taller than average, otherwise they are normal in appearance. They are likely to have weak bones (osteoporosis), unless they are treated with testosterone, and even though they have normal sexual function, however, they are infertile. With the help of new treatments, some men are able to have children.


A person should see a doctor to rule out klinefelter syndrome or another health condition in case he or his son has:

Slow development during infancy or boyhood:

Parents should see their son's doctor in case he is developing more slowly than other boys, though some variation in physical and mental development is quite normal among boys. However, in the case of having any concerns, it is best to check with a doctor. A number of conditions that need treatment including Klinefelter syndrome could have delays in growth and development as their initial sign or symptom. Starting testosterone therapy at the time of the usual onset of puberty could be helpful in treating or preventing a number of problems caused by Klinefelter syndrome.

Male infertility:

A person should see a doctor in case he hasn’t been able to get his partner pregnant after a year of regular, unprotected sex. Although infertility could be caused by something other than this syndrome, however, men are not diagnosed with this condition until they realize that they are not able to father a child. Although a person will still need treatment for the condition, however, he probably won't have children in case he has Klinefelter syndrome.


When an extra sex chromosome is inherited from one of the parents during the formation of the embryo, Klinefelter syndrome occurs, which happens entirely by chance because it is a random occurrence. Having a family history of Klinefelter syndrome or having an older mother at birth won't make a person more susceptible to this disorder unlike other chromosomal disorders, such as Down syndrome.



Usually, the complications of Klinefelter syndrome vary from one person to another. Testosterone therapy could prevent or treat some of these complications. Klinefelter syndrome could cause some of these complications:


  • Weak bones (osteoporosis)
  • Delayed puberty
  • Social development or learning problems
  • An increased risk of venous ulcers, varicose veins and other problems with blood vessels.
  • Increased belly fat, which raises the risk of health problems, such as heart disease and diabetes
  • Noticeable physical features, including unusually long legs, gynecomastia (enlarged breast tissue), limited facial and body hair and lack of muscular development.
  • Increased risk of certain health conditions that usually affect women, such as breast cancer
  • Infertility; only in some rare cases can men with Klinefelter syndrome have children.


Low testosterone (hypogonadism) is associated with a number of complications that are caused by Klinefelter syndrome. When started at the beginning of puberty, testosterone replacement therapy could reduce the risk of certain health problems.


Treatment could help minimize the effects of Klinefelter syndrome despite the fact that the sex chromosome changes cannot be repaired.



When males have Klinefelter syndrome, they don't produce enough of the male hormone testosterone, which could have some lifelong effects. As mentioned before, when testosterone treatment is started at the usual onset of puberty, it could prevent a number of problems that are caused by this syndrome. Testosterone could be given either as injections or with a gel or patch on the skin. This therapy allows the development of facial and body hair, increase in muscle mass and enlargement of the penis, along with other changes that normally occur at puberty. The risk of osteoporosis (thinning bones) is also decreased by this treatment. However, it will not improve infertility or result in testicle enlargement.



Due to the effects of Klinefelter syndrome, some males develop breasts, a condition known as gynecomastia. For a teenage boy or a young man, this could be a serious emotional challenge. A plastic surgeon could remove excess breast tissue and leave a normal-looking male chest. The growth of breast tissue could also be reduced by testosterone replacement.



Most of the men with Klinefelter syndrome are infertile. However, there are alternatives such as artificial insemination with donor sperm or adoption. A procedure known as TESE (testicular sperm extraction) and ICSI (intracytoplasmic sperm injection), in which sperm is removed from the testicle with a biopsy needle and injected directly into the female egg, could benefit some men with Klinefelter syndrome. However, this procedure is not widely available and is quite costly.  Some men with Klinefelter syndrome have fathered children since the introduction of this treatment in 1996.



Particularly during puberty and young adulthood, having Klinefelter syndrome could be a challenge. Additionally, coping with infertility could be difficult for men with this disorder. Meeting with a psychologist or a counselor in order to work through these emotional issues could be beneficial.



In some cases, boys with Klinefelter syndrome could benefit from extra assistance because they have trouble learning. Parents could talk to their child's teacher or school counselor about the kind of support that could help the child. It is important to monitor their development and seek help. However, not all boys with Klinefelter syndrome have learning difficulties.



These are the kinds of treatments that help boys with Klinefelter syndrome overcome poor muscle tone and speech and language problems, as well as other signs and symptoms of this disorder.


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