Fragile X Syndrome

[fra-jɘl \- ‘eks-\ sin-drōm]

DNA illustration of Fragile X syndrome

Fragile X syndrome is one of the most common inherited causes of intellectual disability, which is a term used when there are limits to a person’s ability to learn at an expected level, and function in daily life. Fragile X syndrome is caused by a change in a gene. This change makes it hard for cells to produce a protein that is needed for normal brain function. Currently, there is no cure for fragile X syndrome. The sooner children are diagnosed with fragile X syndrome, the sooner they can benefit from care and services. There are behavioral treatments, medicines, and educational services that may help.


Key Facts

  • The average age at diagnosis for fragile X syndrome is 35 to 37 months for boys and 42 months for girls.
  • Learning disabilities, hyperactivity, attention problems, developmental delays, and seizures are some possible symptoms of fragile X.
  • Fragile X syndrome can increase the chance of being diagnosed with autism spectrum disorder.
  • Females with fragile X syndrome often have milder symptoms than males.
  • The gene involved in fragile X syndrome is called Fragile X Messenger Ribonucleoprotein 1 (FMR1).


Magnified ear
Magnified Ear

Sometimes people with fragile X syndrome can have certain physical features like larger ears, but that’s not always the case.

Doctor consulting with mother and daughter
Family Check-Up

Both girls and boys can have fragile X syndrome, and both can have symptoms that range from mild to severe.

Large family smiling
Extended Family

Fragile X syndrome is caused by an abnormal increase in size of some genetic material when it is passed from one generation to the next. Changes that exceed a certain size often cause fragile X syndrome.

Boy getting blood test
Fragile X Blood Test

Fragile X syndrome requires a special blood test that is not usually included in the genetic tests that a pregnant woman gets or in the tests done right after a baby is born. The only way to diagnose fragile X syndrome is by getting the “FMR1 DNA Test for Fragile X.”

Prevention Tips

Although FXS is not a preventable condition, here are some tips for early detection and better management:

  • If you’re concerned about your child’s development, talk to your child’s doctor.
  • If your child has developmental or intellectual disability with no known cause, consider asking your doctor for the fragile X syndrome test, which is called the “FMR1 DNA Test for Fragile X.”
  • Currently, there is no cure for fragile X syndrome, but there are behavioral treatments, medicines, and educational services that may help your child.
  • Having a diagnosis of fragile X syndrome for your child can help you connect with support groups of other families in the same situation.
  • Tremors and early menopause are symptoms of disorders that can be related to fragile X syndrome. If you or other members of your family have these symptoms, discuss them with your doctor, even if you don’t have a family history of fragile X syndrome.d