What happens in fragile X syndrome, exactly?

What is it?

Fragile X syndrome (FXS) is a genetic syndrome that leads to intellectual disability. People suffering from FXS often have certain typical physical characteristics like a long face, large ears, and less muscle mass. They often suffer from learning difficulties and social anxiety, and their speech can be cluttered and nervous. Almost half of the children affected by FXS qualify for the diagnosis of autism.

Because the severity of FXS come in “grades” it’s not obvious who should be diagnosed with the syndrome and who shouldn’t. It is thought, however, that about 1 in 3600-4000 males suffer from FXS, while the number in females is 1 in 4000-6000.

What causes it?

FXS is caused by a mutation in a gene in the X chromosome.Women inherit two X chromosomes, one from each parent, but men inherit only one from their mother. This is why all men who get the faulty gene will be affected by the syndrome while not all women who get only one faulty gene will develop symptoms.

What happens during it?

Genes are the instructions of proteins, and proteins are essential to basically everything that happens in our bodies. The gene that is mutated in FXS happens to be a very important one – it helps to form new connections between neurons, which is essential to learning and the development of normal cognitive skills.

The mutations don’t actually happen in the area that codes for the protein. They happen in an area that is supposed to help begin the reading of the gene so that it can be translated into a protein. There are normally about 5-55 repeats of a certain coding unit in this area, but this number can increase through mutation. Over 200 repeats means that this area of the gene will undergo chemical changes that prevent it from ever being read. The cell has the right instructions to produce the protein, but it just never gets produced because the reading can’t be started.

How can it be treated?

There is currently no treatment or cure that would address the underlying problem of FXS. Treatment is mainly focused on alleviating symptoms like hyperactivity, anxiety, and impulsivity, and helping the patient live as normal a life as possible. Medication, therapy, and supporting and guiding the parents of a child with FXS can all be very useful.



Sources: en.wikipedia.org/wiki/Fragile_X_syndrome, https://en.wikipedia.org/wiki/FMR1, https://fragilex.org/fragile-x/prevalence/




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