What is Fragile X Syndrome (FXS)?
Fragile X syndrome is a genetic condition and the prevalence of FXS in males is estimated to be between 1 in 4000 and 1 in 7000, and in females between 1 in 6000 and 1 in 11,000 in the US. FXS has been detected in all populations and ethnic groups.
FXS is caused by mutations in the FMR1 gene which is on the X chromosome. It is diagnosed more commonly in males than females, and males display more severe symptoms of the syndrome. Males, having only one X chromosome (XY), will develop FXS because the mutation is on their single X chromosome. Females, who have two X chromosomes (XX), can have the unaffected X reduce the effects of the affected X. This typically leads to no or milder symptoms of FXS. Changes in the FMR1 gene prevent the protein production of this gene, a protein needed for brain development.
How is Fragile X Syndrome diagnosed?
The FMR1 DNA test — also called the Fragile X DNA test. DNA testing detects more than 99% of individuals (both males and females) with FXS, as well as premutation carriers. Many labs now offer the ability to do Fragile X testing on a saliva or buccal (cheek swab) sample. The testing is very accurate for all sample types, and the type of sample submitted does not influence the results.
Major genetic testing labs currently require an order from a healthcare provider. This is an important safeguard to ensure that individuals being tested receive appropriate notification, education, follow-up, and medical support about the meaning of the results. Talk to the individual’s primary care provider
(PCP) if there are concerns.
When a child is diagnosed with FXS it is important to seek out Early Intervention. The PCP or the local school district should be able to provide more information.
Behavioral characteristics may include ADD/ADHD, autism spectrum disorder and autistic behaviors, social anxiety, hand-biting and/or flapping, poor eye contact, sensory processing issues, and increased risk for aggression.
Cognitive abilities in FXS range from moderate learning disabilities to more severe intellectual disabilities. Most males with Fragile X syndrome demonstrate moderate intellectual disability.
Physical features may include large ears, long face, soft skin, and large testicles (called “macroorchidism”) in post-pubertal males.
Connective tissue features may include ear infections, flat feet, high arched palate, double-jointed fingers, and hyper-flexible joints.
It is important to note the many positive aspects are often found in those with FXS including that they can be very social and friendly, have excellent imitation skills and strong visual memory/long term memory. They like to help others, want to please and make others happy, are nice, thoughtful, and have a wonderful sense of humor.
Strategies for Working with Individuals with FXS
Individuals with FXS are prone to hyperarousal and anxiety. It is how their nervous systems are wired. Don’t force eye contact. Eye contact will come naturally as the individual becomes more comfortable with you.
Individuals with FXS are “simultaneous” vs “sequential” learners. They are good sight word learners. They need to see and understand the “whole” and not the parts that add to a whole. When doing an activity, allow and/or encourage frequent breaks. Accommodate attention difficulties by keeping tasks brief.
Verbal expression is cognitively taxing. Avoid direct, open-ended questioning: prompt “The President of the United States is …” vs. “Who is the President of the United States?” Think “indirect”. There are times when individuals with FXS enjoy attention, but most often they are averse to the limelight. Give compliments in the 3rd person about the individual to others within earshot.
Prepare for transitions. Give 10- and 5-minute prompts. Allow to be at the head or back of the line. Use social stories about routine transitions. Provide a purposeful errand so the focus is on the outcome (e.g., delivering an envelope) rather than moving from one place to another. Individuals with FXS are visual learners. Visuals function as an ongoing means of keeping hyperarousal in check.
Work with an occupational therapist knowledgeable about sensory integration. A sensory diet consists of a carefully planned program of specific sensory-motor activities that is scheduled according to each child’s individual needs. Integrate these activities throughout the day to sustain a calm, regulated nervous system: heavy work like rearranging desks, cleaning windows, or moving stacks of books; vestibular input, like going for a walk, doing wall push-ups, and swinging.
Notice environmental triggers. Individuals with FXS often have sensory sensitivities to sound, light, textures, taste, and smell that provoke hyperarousal. Make adjustments to the environment as much as possible. It is critical to integrate knowledge of hyperarousal into any intervention strategy and especially for those treatments that come from a tradition of autism intervention.
The National Fragile X Foundation (NFXF) was founded in 1984 to support individuals with Fragile X syndrome (FXS), their families, and the professionals who work with them. Today, it is a comprehensive resource not only for FXS, but also for the conditions of Fragile X-associated tremor/ataxia syndrome (FXTAS), Fragile X-associated primary ovarian insufficiency (FXPOI), and other premutation carrier issues.
The organization offers help for today and hope for tomorrow with personalized support, community, education, awareness, advocacy, and research. Get your free Fragile X 101 e-book, Welcome Packet, connect with your local chapter, learn about the upcoming conference, and more at
If you have specific questions about what to expect, treatments, clinics, well, just about anything, please email firstname.lastname@example.org or call (800) 688-8765.