Tetrasomy 18p syndrome

What is Tetrasomy 18p syndrome?

It is a rare chromosomal syndrome that affects multiple parts of the body. The main symptoms of the syndrome are usually very obvious in infancy and included difficulties with feeding, delayed development and intellectual disability. However these can vary according to the individual.

As a rare syndrome it is known to affect around 250 families worldwide.

What gene changes cause Tetrasomy 18p syndrome?

The syndrome is caused because of the presence of an extra isochromosome 18p in each cell. This creates extra genetic material disrupts development within an affected individual and triggers the related syndromes.

Generally the syndrome is not inherited, except in very rare cases. It is the result of spontaneous mutations during the process of reproduction.

What are the main symptoms of Tetrasomy 18p syndrome?

The main syndromes affecting infants with the syndrome include difficulties with feeding, frequent vomiting and a subsequent failure to gain sufficient weight. Symptoms in infancy might also include respiratory issues which affect breathing and jaundice.

Delayed development of motor skills (sitting, crawling and walking) is common with the syndrome. This can be caused by weak muscle tone, increased muscle tone or a stiffness known as spasticity.
Some affected individuals might also show symptoms that include ADHA, anxiety and other behavioural issues.
Unique facial features associated with the syndrome include low set ears, a small mouth, a flat philtrum (the area between the upper lip and nose), a thin upper lip and a high arched palate. A cleft palate may also be present.
Seizures, constipation, an abnormal curving of the spine are also possible symptoms.

How does someone get tested for Tetrasomy 18p syndrome?

The initial testing for Thanatophoric dysplasia 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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