Klinefelter syndrome

* This composite image of Klinefelter Syndrome was created to help geneticists get a better analysis

What is Klinefelter syndrome?

This rare disease is a genetic syndrome which occurs when a male infant is born with an extra X chromosome, instead of being born with XY chromosomes. Another name for Klinefelter syndrome is XXY syndrome.

There are three types of the syndrome: where the male has an extra X chromosome in each cell, the mosaic form of the syndrome which is an extra X chromosome in only some of the cells, or the presence of more than one extra X chromosome which is particularly rare and a very severe form of the condition.

What gene change causes Klinefelter syndrome?

The syndrome is caused by the presence of an extra X chromosome in the either all or some of the cells of males.

Usually is sporadic, or de-novo, which mean that it is not inherited.

What are the main symptoms of Klinefelter syndrome?

The symptoms of the syndrome can vary widely between individuals. A lot of males with the syndrome are not diagnosed until puberty or even adulthood due to the absence of symptoms, or the presence of only very mild ones.

The symptoms of the syndrome may vary with age. But the main symptoms include hypotonia (low muscle tone in infancy), delayed physical development and delayed speech development. In later childhood learning difficulties are often identified.

Most males with the syndromes experience issues concerning their puberty. Either they don’t experience it, it starts much later than the average or it never ends.

Physical symptoms of the syndrome include longer arms and legs, a tall stature but a shorter torso.

Infertility and hypogonadic hypogonadotropism are often causes of consultation when diagnosis has not been made until adulthood.

How is Klinefelter syndrome diagnosed?

To find out if someone has a diagnosis of Klinefelter syndrome, it is important to have a consultation and evaluation with a clinical genetic specialist.  Specialists may also suggest specific genetic testing or other types of tests to help reach a diagnosis.  FDNA’s AI technology can help speed up the diagnostic process by analyzing facial features and other health information.

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* This composite image of Klinefelter Syndrome was created to help geneticists get a better analysis

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