Fragile X Syndrome (FXS)

What is Fragile X Syndrome (FXS)?

Fragile X syndrome (FXS) is a genetic or hereditary disorder passed down from parent to child. FXS is the most common cause of inherited intellectual and developmental disabilities. It affects both boys and girls, though it is more common and more severe in boys. Signs that a child might have FXS include not meeting developmental milestones, such as sitting, walking, and talking, on time, trouble learning new skills, social problems, such as not making eye contact, and behavior problems (e.g., anxiety, trouble paying attention, hand flapping, acting and speaking without thinking, and high levels of activity).

Doctors can perform blood tests to determine whether your child has FXS. Males who have FXS may also have an intellectual disability that can range from mild to severe. Females with FXS can have normal intelligence or some degree of intellectual disability. FXS is a common cause of autism spectrum disorders (ASD).

There is no known cure for FXS. However, various therapies and services can help people learn important skills, such as walking, talking, and interacting with others, to live a better life. Important services may include special education programs, occupational therapy (OT), physical therapy (PT), speech/language therapy, behavioral therapy, genetic counseling, and medication management. FXS is a family diagnosis, so it is important for all family members to be tested.