What is Fragile X syndrome?

Fragile X syndrome is an inherited (genetic) condition that causes intellectual disability and physical, behavioural and emotional problems.

Fragile X syndrome is the most common inherited cause of intellectual disability. It affects around 1 in 4,000 males and around 1 in 6,000 females.

What are the symptoms of Fragile X syndrome?

Fragile X syndrome affects different people differently. Someone with Fragile X syndrome may experience only some of the symptoms. Females are usually less affected than males and may have no symptoms.

Fragile X often causes developmental problems, including:

• intellectual disability
• learning problems
• difficulties with communication
• difficulties with coordination and movement

Behavioural and emotional symptoms may include:

• anxiety
• autism spectrum disorder (ASD)
• attention deficit hyperactivity disorder (ADHD)
• mood disorders
• sensitivity to loud noises, bright lights or touch
• trouble making eye contact

Physical symptoms may include:

• weak muscles and joints
• a heart murmur
• a long narrow face
• flat feet
• vision and hearing problems

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What causes Fragile X syndrome?

Fragile X syndrome is caused by a change (mutation) in a gene called FMR1. This gene is needed for healthy brain development. The FMR1 gene is found on the X chromosome. Males have only one X chromosome, while females have 2. This explains why males and females are affected differently.

People with Fragile X syndrome may have a full mutation or a pre-mutation, depending on how much the FMR1 gene has been changed.

Males and some females with the full mutation have symptoms of Fragile X syndrome.

People with the pre-mutation are Fragile X carriers. They usually do not have any symptoms, but they can pass the mutation on to their children.

When should I see my doctor?

Ask your doctor about Fragile X testing if you have a family history of Fragile X syndrome, intellectual disability or autism spectrum disorder.

It’s also a good idea to talk to your doctor about testing if you are pregnant or planning a pregnancy.

Talk to your doctor if you are concerned that your child has symptoms of Fragile X syndrome.

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How is Fragile X syndrome diagnosed?

Fragile X syndrome can be diagnosed at any age by a blood test or a saliva test. This test can show if you have Fragile X syndrome or are a carrier.

If you or your partner is a Fragile X carrier and you are pregnant, you might choose to have a prenatal test to find out whether your baby will be affected. The test involves taking a sample from inside the womb, by amniocentesis or chorionic villus sampling.

How is Fragile X syndrome treated?

Although there is no cure for Fragile X syndrome, there are treatments that can help manage symptoms. The earlier you start the treatment, the more effective it will be. Someone with Fragile X syndrome will be cared for by a multidisciplinary team of health professionals.

Treatment might include:

• medicines to help with mood problems, anxiety or ADHD
• speech therapy to improve communication
• physiotherapy to help with movement problems
• psychological therapies
• help with learning problems

Living with Fragile X syndrome

Some adults with Fragile X syndrome can live independently, while others benefit from supported accommodation. They may need help with finding employment that is a good fit for them.

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Can Fragile X syndrome be prevented?

If you or your partner is a Fragile X carrier and you are planning a pregnancy, it’s important to have genetic counselling. A genetic counsellor can tell you about your risk of having a child with Fragile X syndrome.

If you are at high risk, you may want to use preimplantation genetic diagnosis (PGD) to avoid having a child with Fragile X syndrome. This involves using in vitro fertilisation (IVF) instead of becoming pregnant naturally. Your embryos can then be tested for the Fragile X mutation, and only embryos who do not carry the mutation will be transferred back into your uterus (womb).

Complications of Fragile X

Carriers of the Fragile X pre-mutation might develop health problems such as:

• Fragile X tremor ataxia syndrome, which causes a tremor, movement difficulties and memory problems after 40 years of age
• Fragile X primary ovarian insufficiency, which can cause infertility and early menopause in females
• mental health conditions such as depression and anxiety

Resources and support

The Fragile X Association of Australia provides support and counselling to families living with Fragile X syndrome.

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

Funding for support services may be available through the National Disability Insurance Scheme (NDIS).