Fragile X syndrome (FXS) is a genetic problem that results in intellectual disability.
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FXS is inherited from parents. It is caused by problems with the FMR1 gene. These problems stop the fragile X mental retardation protein (FMRP) from developing. This protein is needed to make connections in the brain.
The risk of this problem is higher in people who have a family history of the faulty FMR1 gene.
Problems are different from person to person. They happen less often and are mild in females. Problems may be:
- Learning problems
- Slowed development
- Speech problems
Behavioral problems, such as:
- Mood swings
- Being very sensitive to loud noises or bright lights
- Extreme shyness, especially in girls
Physical problems, such as:
- A long face with a jaw that sticks out
- Large ears
- Flat feet
- Joints that bend past normal limits
- A high-pitched voice and enlarged testes in males after puberty
- Floppy muscles
- Problems with motor skills like sitting and walking
The doctor will ask about your child's symptoms and health history. A physical exam will be done.
The diagnosis can be confirmed with a genetic test.
There is no cure for FXS. The goal is to manage symptoms. Choices are:
- Medicines, such as:
- Stimulants to treat attention and behavior problems
- Medicine to control mental health problems
- Antiseizure medicines
- Speech, occupational, physical, or behavioral therapy
- Special education services to help with learning
There are no known guidelines to prevent this health problem.
Fragile X syndrome. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/fragile-x-syndrome. Accessed November 4, 2020.
Fragile X syndrome overview. National Institute of Child Health and Human Development website. Available at: http://www.nichd.nih.gov/health/topics/fragilex/Pages/default.aspx. Accessed November 4, 2020.
Lozano R, Azarang A, et al. Fragile X syndrome: A review of clinical management. Intractable Rare Dis Res. 2016 Aug;5(3):145-157.
What is fragile X? FRAXA Research Foundation website. Available at: http://www.fraxa.org/fragilex. Accessed November 4, 2020.
Last reviewed September 2020 by EBSCO Medical Review Board
Kari Kassir, MD
Last Updated: 5/11/2021