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Fragile X syndrome (FXS) in children

Overview

What is fragile X syndrome (FXS) in children?

Fragile X syndrome (FXS) is caused by a mutation of a single gene FMR and is a genetic or hereditary disorder passed down from parent to child. FXS is the most common cause of inherited intellectual and developmental disabilities. 

Risk factors

It affects both boys and girls, though it is more common and more severe in boys.

  • Males - approximately 1 in 4,000 to 1 in 7,000

  • Females - approximately 1 in 6,000 to 1 in 11,000

Signs and Symptoms

What are the signs and symptoms of fragile X syndrome (FXS) in children?

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). 

FXS is a common cause of autism spectrum disorders (ASD).

  • 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.

Diagnosis

How is fragile X syndrome (FXS) diagnosed?

Doctors can perform blood tests to determine whether your child has FXS. FXS is a family diagnosis, so it is important for all family members to be tested.

Treatment

How is fragile X syndrome (FXS) treated?

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:

Resources