What is Fragile X syndrome?

People with Fragile X syndrome (or Fragile X) have intellectual disability, behavioural and learning challenges as well as certain physical characteristics. Fragile X is the most common inherited cause of intellectual disability, and also the most common known genetic cause of autism. It affects around one in 4,000 males and around one in 6,000 females.

Fragile X is caused by a change in a single gene, the FMR-1 gene. This gene helps create a protein that is needed for healthy brain development.

Types of Fragile X syndrome

Depending on how a person’s FMR1 gene has been changed by the Fragile X mutation, they are said to either have the full mutation, or a pre-mutation.

People with the full mutation show symptoms of Fragile X. People with the pre-mutation may not show any symptoms, but are carriers of Fragile X.

Symptoms or signs of Fragile X syndrome

Fragile X can affect people differently. Girls and women are usually less affected than boys and men. A person may be fully affected by Fragile X but not show all of these signs below:

• intellectual disability, slow development and difficulties with communication, coordination, motor skills and learning
• behavioural and emotional features such as aggression, anxiety, shyness and repetitive speech
• physical symptoms such as weak muscles and joints, a heart murmur and a high palate

Fragile X syndrome diagnosis

A diagnosis of Fragile X can be made at any age, by doing a blood test. This test can show whether or not someone is affected by Fragile X or whether they are a genetic carrier.

If you or your partner have Fragile X or are a carrier, and are expecting a baby, you might be able to get a pre-natal test to find out whether your baby will be affected.

Visit Pregnancy, Birth and Baby website for more information about Fragile X and babies.

Carriers of Fragile X

Carriers of Fragile X might develop certain health conditions later in life, such as:

• Fragile X tremor ataxia syndrome, or FXTAS, which causes a tremor and mainly affects men over 50 years
• Fragile X primary ovarian insufficiency, or FXPOI, which can cause infertility and early menopause in women

Living with Fragile X syndrome

Although there is no cure for Fragile X, treatments (including some medications) can help improve quality of life, especially if received early on. Ideally, each person with Fragile X will be cared for by a multidisciplinary team of health professionals.

Where to go for help

The Fragile X Association of Australia provides support to families living with Fragile X syndrome. This includes specialised clinics, workshops, genetic counselling and casework.

More information

Visit healthdirect's genetic disorders guide to learn more about genes, types of genetic disorders and where to go for help and more information.