What is fragile X syndrome?

Fragile X syndrome is an inherited (genetic) condition that affects around 1 in 4000 males and 1 in 6000 females. It is caused by a change (mutation) in a gene on the X chromosome that is important for healthy brain development.

Fragile X syndrome is the most common inherited cause of intellectual disability and the most common genetic cause of autism.

What are the symptoms of fragile X syndrome?

Some children with fragile X have very few symptoms, while others have significant health problems. Symptoms also differ between males and females. Females tend to have less or milder symptoms than males.

Fragile X syndrome often causes developmental problems, including:

• speech and language delays
• intellectual disabilities and learning difficulties
• hyperactivity and ADHD
• difficulties with communication
• difficulties with coordination and movement

Physical features of fragile X include:

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

Children with fragile X syndrome may also have behavioural and emotional problems including:

• shyness, aggression or mood swings
• attention deficit hyperactivity disorder (ADHD) or autism spectrum disorder
• anxiety and related problems such as obsessive-compulsive disorder

What causes fragile X syndrome?

Fragile X syndrome is caused by a genetic mutation (change) on the X chromosome — 1 of the 2 chromosomes that determine your sex at the time of conception.

Chromosomes carry DNA (deoxyribose nucleic acid). A gene is a small section of that DNA responsible for inherited characteristics. Sometimes, the X chromosome develops a fault, causing its DNA to change.

Fragile X syndrome occurs when a specific gene on the X chromosome mutates (changes). If the gene changes a lot, you may have a full mutation. A person with a full mutation will be born with symptoms of fragile X syndrome.

If the gene only changes a bit, you may have what is known as a ‘pre-mutation'. People with a pre-mutation can pass the faulty gene on to their children (be carriers), but may not have any symptoms.

Fragile X syndrome is more common and severe in males, as they have one X chromosome and one Y chromosome. Females have two X chromosomes. This means that even if females carry the fragile X mutation on one X chromosome, the other one usually functions properly.

When should my child see a doctor?

Speak to your doctor about testing for Fragile X syndrome if:

• your child show signs of intellectual or learning disability and developmental delays
• your child show signs of behavioural or emotional problems
• you have a family history of fragile X syndrome, intellectual disability or autism spectrum disorder.

How is fragile X syndrome diagnosed?

If you have a child of any age showing symptoms of fragile X syndrome, your doctor can refer them for a DNA blood test to see if they have the condition. Having a diagnosis can help your child get the help they need.

Fragile X syndrome is detected by a DNA test. This is usually a blood test or saliva test.

The test will identify the gene that causes fragile X syndrome and can tell you whether your child has a normal gene, a pre-mutation or full mutation.

How do I know if I am a carrier for fragile X?

You can be tested before becoming pregnant to see if you are a carrier of the gene for fragile X. Carrier testing is recommended if you:

• have a family history of fragile X
• have a family history of fragile X-associated disorders, intellectual disability or autism spectrum disorders
• are planning a pregnancy
• experience early menopause (primary ovarian insufficiency)

If you are a carrier, there is a chance that you can pass the gene on to your children. Even if you don't have a family history of fragile X, you can still have a genetic test to find out if you are a carrier for the condition.

If you do have a family history of fragile X syndrome or any associated disorders, the diagnostic test may be covered under Medicare.

If you are a carrier of the fragile X gene, a genetic counsellor can help you explore ways of having a healthy baby.

Can fragile X syndrome be detected during pregnancy?

If you or your partner are a known carrier for fragile X, your baby can be tested during pregnancy using amniocentesis or chorionic villous sampling.

If your baby is found to have fragile X, you can consider whether to continue with the pregnancy or think about a termination. Your doctor can refer you to a genetic counsellor who specialises in helping people in your situation. You can also call Pregnancy, Birth and Baby for advice and support.

How is fragile X syndrome treated?

There is no cure for fragile X but there are effective treatments for problems your child may experience. You can help your child reach their potential by getting them help as soon as possible after diagnosis. This is called early intervention.

A team of different specialists can work together to look after your child's educational, behavioural and medical needs. This team may also include a psychologist to help your family work through some of the challenges involved in supporting a person with a disability. They can also help you to speak to your child's school to develop an educational plan. If needed, you may also meet with:

• an audiologist to assess your child's hearing
• an optometrist or ophthalmologist to check vision
• a podiatrist to fit orthotics
• a speech pathologist to help your child with communication
• an occupational therapist to assist with behaviour management

Your doctor can advise you about any medicines that can help your child any behavioural and emotional challenges.

Living with fragile X syndrome

It can be overwhelming to receive a diagnosis of fragile X syndrome. It's a good idea to think about seeking support from family or friends as you process the diagnosis.

Your child may have behavioural challenges and a unique style of learning. Speak to your doctor or occupational therapist about creating a learning environment best suited to your child.

If your child is diagnosed with fragile X syndrome, you may be eligible for support from the National Disability Insurance Scheme (NDIS). This can help you to fund early intervention therapies for your child.

What are the complications of fragile X syndrome?

Children with fragile X syndrome may have additional health challenges that can affect their daily lives. Common health problems include:

• anxiety
• increased sensitive to environmental triggers
• attention deficit hyperactivity disorder (ADHD)
• aggression
• epilepsy or seizure disorders

Carriers of the fragile X pre-mutation might develop health problems including:

• 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
• mental health conditions such as depression and anxiety

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 choose 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).

Resources and support

Raising a child with a disability is not easy, but help is available.

• Call the Carer Gateway on 1800 422 737 for support and services.
• The Fragile X Association has a helpline on 1300 394 636 and provides advice on treatments and early intervention.
• The National Fragile X Foundation has resources for parents and teachers on living with Fragile X. They also provide real-life stories about living with Fragile X.

For more information for people planning a pregnancy:

• Genetic services and clinics can be found through the Centre for Genetics Education website.
• Find genetic counselling services on the Human Genetics Society of Australasia website.