Klinefelter syndrome (KS) is a chromosomal condition that describes boys and men with common features, physical traits and medical conditions that are caused by the presence of an extra X chromosome (i.e., XXY).
Both males and females generally have 46 chromosomes. In females, this includes two X chromosomes, while males have one X and one Y chromosome.
It is estimated that
one in 500 to 1,000 males are born with 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:
Children and adolescents with KS may experience:
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.
The following problems can also be seen in individuals with KS, and need to be monitored for and treated if present:
KS occurs when an extra X chromosome is present before or soon after the time of conception. In most instances, this occurs spontaneously and is not inherited from either parent.
The diagnosis of KS is made by looking at the complete set of chromosomes of the individual. This is called a karyotype. A karyotype shows the number and visual appearance of the chromosomes found in the cells of a person.
While it is not possible to cure KS, much can be done to make sure your child has the best possible outcome.
The multidisciplinary medical team looking after your child will be able to address specific medical concerns and routine KS-related healthcare issues.
Below are some related medical issues and how they can be managed:
Testosterone therapyTestosterone can be given in the form of injections or tablets. It is usually started from puberty and continued through adulthood.
Testosterone replacement can help to:
Recurrence risk is low (<1%). However, risk has been shown to increase with increasing maternal age.
KS is a lifelong condition. Should you require financial assistance or emotional support, please approach your doctor for referral to a medical social worker.
Download the Klinefelter Syndrome brochure.
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