Fragile X syndrome is the most common known cause of inherited intellectual disability, affecting around 1 in 4000 males and about 1 in 6,000 females.

It is one of a family of conditions caused by a mutation (change) to the FMR1 gene on the X chromosome. The FMR1 gene is responsible for producing a protein important for brain development. When the gene lengthens through the mutation, it switches off production of that protein involved in brain development and other functions.

Fragile X syndrome can cause a wide range of difficulties with learning, as well as social, language, attentional, emotional, behavioural and medical problems. The effects of Fragile X syndrome on an individual vary and can range from mild to severe. Men and boys commonly appear more severely affected by Fragile X syndrome, but women and girls may also be severely affected.

Fragile X syndrome is also the most common known single-gene cause of autism spectrum disorder. Up to 50% of males with Fragile X syndrome will meet the criteria for autism spectrum disorder. Approximately 2% of people who meet the criteria for a diagnosis of autism spectrum disorder have been found to have Fragile X syndrome.

It is estimated that in Australia, each week one child is born with Fragile X syndrome, and 20 children are born who are carriers of the FMR1 gene premutation.

While there is as yet no cure for Fragile X syndrome, there are a range of treatment interventions and management strategies that are of great benefit.

Photo credit: Genome Research Limited