Fragile X syndrome is a genetic condition that affects 1 in 4,000 boys and 1 in 8,000 girls worldwide, and yet many people have never heard of it. July 22nd marks the 14th anniversary of National Fragile X Syndrome Awareness Day, which was established to help raise awareness about this common yet ‘rare’ disease.

What is Fragile X syndrome?

Fragile X syndrome (FXS) is a genetic condition that causes developmental delay in affected individuals, mainly cognitive impairment and learning disabilities. It is the most common cause of autism. Other symptoms of FXS include ADHD and seizures.

How is it inherited?

FXS is caused by changes in the FMR1 gene on the X chromosome, meaning that it’s an X-linked condition. The specific genetic change that causes FXS is an expansion in the number of “CGG” repeats within the FMR1 gene. It is normal to have up to 44 CGG repeats. When a person has 200 or more CGG repeats (a full mutation), he or she can have FXS. Because males only have one X chromosome, all males with a full mutation will have FXS. In contrast, females have two copies of the X chromosome, therefore, not all females with a full mutation will have classic FXS, or they may have a milder form. Individuals who have between 45 and 54 CGG repeats have ‘intermediate’ mutations that can expand over generations, but they themselves are not at risk to have a child with FXS. Individuals who have between 55 and 200 repeats have a ‘premutation’, and women premutation carriers in particular are at risk to have a child with FXS. Individuals with premutations are also at risk for Fragile X-associated tremor/ataxia syndrome (FXTAS) and Fragile X-associated primary ovarian insufficiency (FXPOI). FXTAS is a movement disorder with symptoms including short-term memory loss, Parkinsonism, and lower limb muscle weakness. FXPOI causes problems with ovarian function leading to early menopause and infertility. Approximately 1 in 250 women and 1 in 800 men are premutation carriers.

What treatments are available?

Unfortunately, there is no cure for FXS and treatment focuses around managing the symptoms of the condition. Children with FXS are typically enrolled in early intervention programs and special education classes; these have been shown to improve developmental progress. Some children may need medication to manage behavioral issues.

Where can I learn more?

To learn more about FXS, please visit Visit Faces of Fragile X to read stories about individuals with FXS, and visit NFXF Let ‘Em Know 5K to learn about how you can help raise money for FXS research.