- Patient Comments: Fragile X Syndrome - Experience
- Patient Comments: Fragile X Syndrome - Carrier
- Patient Comments: Fragile X Syndrome - Educational Options
- Fragile X syndrome facts*
- What is Fragile X syndrome?
- What causes Fragile X syndrome?
- What keeps the FMR1 gene from producing FMRP in Fragile X syndrome?
- Human cells 101
- How many people are affected by Fragile X syndrome?
- How is Fragile X syndrome inherited?
- What are the signs and symptoms of Fragile X syndrome?
- Intelligence and learning
- Social and emotional
- Speech and language
- Is there a cure for Fragile X syndrome?
- Are there treatments for Fragile X syndrome?
- Educational options
- Therapeutic options
- Medication options
- What are the options for adults who have Fragile X syndrome?
- What should I do if I find out someone in my family has Fragile X syndrome?
- What is being done to develop treatments or a cure for Fragile X syndrome?
- Where can I go for more information about Fragile X syndrome?
What is Fragile X syndrome?
Fragile X syndrome (also called Fragile X) is the most common inherited form of mental retardation.* It results from a change, or mutation, in a single gene, which can be passed from one generation to the next. Fragile X appears in families of every ethnic group and income level.
Symptoms of Fragile X syndrome occur because the mutated gene cannot produce enough of a protein that is needed by the body's cells, especially cells in the brain, to develop and function normally. The amount and usability of this protein, in part, determine how severe the effects of Fragile X are.
The most noticeable and consistent effect of Fragile X is on intelligence. More than 80 percent of males with Fragile X have an IQ (intelligence quotient) of 75 or less.1 The effect of Fragile X on intelligence is more variable in females. Some females have mental impairment, some have learning disabilities, and some have a normal IQ.
People with Fragile X syndrome also share certain medical problems as well as many common physical characteristics,2 such as large ears and a long face. In addition, having Fragile X is often associated with problems with sensation, emotion, and behavior.
The National Institute of Child Health and Human Development (NICHD), part of the National Institutes of Health (NIH), is a major sponsor of research on Fragile X syndrome. Since 1991, when researchers funded by the NICHD discovered the gene that causes Fragile X, scientists have learned a great deal about that gene's structure and functions. The NICHD continues to support clinicians and scientists around the world who are working to find effective behavioral or other therapies, medical treatments, and prevention strategies for Fragile X.
* The NICHD recognizes that there is a debate about the use of the term "mental retardation," and that self-advocacy groups and professional associations are currently discussing alternative terms. Until a consensus is reached, and with the goal of addressing health-related issues faced by people with what has been traditionally known as "mental retardation," this article uses that term to describe some features related to Fragile X syndrome. For more information, please see the Additional Resources section of this article.