49,XXxxy syndrome

What is 49,XXxxy syndrome?

This rare disease is a chromosomal condition that affects only males.

It is sometimes referred to as a variant of Klinefelter syndrome, but it affects individuals much more severely and varies in many ways in terms of the possible symptoms.

The main features of this syndrome include intellectual disability, infertility, birth defects and unique facial features.

What gene changes cause 49,XXxxy syndrome?

The condition is caused by the presence of 3 extra x chromosomes in affected males. It is not inherited.

It is believed to be the result of mosaicism.

Mosaicism occurs when an individual has cells in their body with more or less chromosomes than the usual 46. This can trigger issues that affect different systems and parts of the body.

What are the main symptoms of 49,XXxxy syndrome?

Symptoms may vary considerably between individuals with the syndrome.

Some of the main symptoms include intellectual disability and developmental delay.
Delayed growth is common and may present as early as in the uterus.

Birth defects are also common and may affect the heart, brain, bones and kidneys.

Unique facial characteristics of the syndrome include a short stature, short neck, folder ears, a protruding lower jaw, a large and flat nose with a turned up tip, and wide-set eyes.

Infertility is also a main symptom of the syndrome.

How does someone get tested for 49,XXxxy syndrome?

The initial testing for 49,XXxxy syndrome can begin with facial analysis screening, through the FDNA Telehealth telegenetics platform, which can identify the key markers of the syndrome and outline the need for further testing. A consultation with a genetic counselor and then a geneticist will follow. 

Based on this clinical consultation with a geneticist, the different options for genetic testing will be shared and consent will be sought for further testing.   

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