Fragile X syndrome

Fragile X syndrome is the most common inherited cause of intellectual disability and autism features. It results from the loss of function of the FMR1 gene.
Fragile X syndrome (FXS) affects about one in 4,000 males and 1 in 9,000 females.
It is caused by an expanded CGG repeat (>199 repeats) in the FMR1 gene. This in turn causes a chemical change to DNA called methylation that silences the gene. A smaller sequence of 55 to 199 CGG repeats in the FMR1 gene is known as premutation. Premutations are common, found in about 1 in 700 males and 1 in 300 females. Women who have a premutation are at risk of having children affected with FXS.
Diagnosis is by a genetic test usually ordered by a paediatrician. Early diagnosis enables early interventions and genetic counselling.

Who does it affect?
Who does it affect?
- In Australia, about one in 4,000 boys and 1 in 9,000 girls have Fragile X syndrome.
- Fragile X syndrome occurs in children of all ethnic backgrounds.
- More than 7,000 Australians have Fragile X syndrome
- More than 50,000 Australian women are at risk of having children with Fragile Syndrome because they have a premutation.
Our Fragile X syndrome research
Our Fragile X syndrome research
We are working on the development of new tests to enable earlier diagnosis, including newborn screening. These tests may be able to predict future problems with health and development and detect children who are missed by existing tests.
One is a world-first test we developed which can detect the syndrome at birth. We are studying how often the syndrome occurs and how well this test works in the world’s largest Fragile X trial involving 100,000 newborns.
We are using the co-design framework and online surveys to understand the needs and experiences of adult premutation carrier females.
We are developing gait-analysis wearable technology for use as a real-world (non-laboratory) digital-endpoint in clinical trials and research with children who have Fragile X syndrome.
Impacts of our research

Impacts of our research
- Fragile X syndrome is estimated to cost the Australian economy up to $180 million a year, or $2.5 million per affected child.
- We have developed world-first genetic tools that may make possible the inclusion of fragile X as part of the newborn heel-prick test. If the condition is detected early as part of newborn screening it would also give families more options for the future, including faster access to treatments and the choice to have children using preimplantation genetic diagnosis through IVF, who would be unaffected.
- In addition to screening for fragile X, this blood test screens babies for three chromosome 15 imprinting disorders, including Prader Willi Syndrome, where there are targeted treatments available from birth.
- We are also collecting information on the cost of raising a child with Fragile X to show the government that routine screening is cost-effective.
- Our work with adult female premutation carriers is being conducted with the goal of ultimately informing the development of a national standard of care for this group that is evidence-based, with carefully planned dissemination that is effective, ethical and meaningful.
- Our new techniques in non-laboratory testing of gait and balance in children who have Fragile X syndrome could one day reduce the testing load for families in clinical trials and lead to highly sensitive, objective data collection from the home or community environment.
Our vision
Our vision
Our vision is to effectively diagnose and build national consistent frameworks around the care and management of Fragile X as early as possible. This will enable timely access to interventions and treatments that improve life for children affected by this complex syndrome and to provide accurate advice to their families from birth to enable informed future reproductive options.