Understanding Fragile X
Fragile X-associated Disorders are a family of inherited conditions caused by alterations (expansions) in the FMR1 gene (Fragile X gene) which is located on the X chromosome. These disorders include a wide range of physical, intellectual and behavioural symptoms that can affect family members in different ways.
It is estimated that about 90,000 people in Australia are impacted by Fragile X in some way – as carriers of Fragile X, or with Fragile X syndrome.
Fragile X syndrome
Fragile X syndrome is the leading cause of inherited intellectual disability, affecting about 1 in 4,000 males and about 1 in 6,000 females.
Both males and females can be carriers of the Fragile X gene alteration, and are called premutation carriers. About 1 in 250 women and 1 in 800 men are Fragile X premutation carriers.
Conditions associated with being Fragile X Premutation Carriers include:
- Fragile X-associated Tremor Ataxia syndrome (FXTAS): A neurological condition with symptoms including shaking (intention tremor), unsteadiness (ataxia) and memory problems. FXTAS is often misdiagnosed as Parkinson’s disease
- Fragile X-associated Primary Ovarian Insufficiency (FXPOI): Which can lead to fertility problems and early menopause
- Fragile X-associated Neuropsychiatric Disorders (FXAND): A term to describe a range of physical and psychological issues some carriers may experience
How is Fragile X passed on in families?
With each pregnancy, female premutation carriers have a 50% chance of passing on the Fragile X gene change either as a premutation or a full mutation to a child of either sex.
Testing and Screening for Fragile X
As Fragile X is an inherited genetic condition, if a person finds out they have the premutation or full mutation other family members may also be carriers and/or may have a Fragile X associated condition.