About Fragile X Syndrome

What is Fragile X Syndrome?

Fragile X Syndrome is a genetic condition and is the most common inherited cause of learning disabilities. It affects around 1 in 4000 boys and men, as well as 1 in 8000 girls and women. 


Below you will find an introduction to Fragile X. If you would like more detailed information about Fragile X, including about specific issues like behaviour or educational needs, then you can download our publications. You can also get support and information from the Fragile X Society via our Families and Professionals Advisors


How does Fragile X Syndrome affect people? 

There are a wide range of characteristics associated with Fragile X, but an individual person may only experience some of these. Learning disabilities occur in almost all boys with Fragile X, to differing degrees. Some boys have severe learning disabilities, although this is rare. Girls usually have milder learning disabilities than boys, but this is not always the case. Some girls with Fragile X Syndrome may be clinically unaffected.


As well as learning disabilities, common behavioural features include short attention span, distractibility, impulsiveness, restlessness, over activity and sensory problems. Girls with or without learning disabilities may show concentration problems and social, emotional and communication difficulties related to extreme shyness and anxiety in social situations.


Many children and adults show autistic like features, including: avoiding eye contact, anxiety in social situations, insistence on familiar routines and hand flapping or hand biting. Although many people with Fragile X relate well to others, anxiety in unfamiliar or unpredictable situations may cause them to act in this way. A substantial minority of individuals with Fragile X will show greater problems relating to others and may receive a dual-diagnosis of autism. Speech and language are usually delayed with continuing speech and communication problems. Some children and adults develop epilepsy.


However, strengths associated with Fragile X include good imitation skills, visual learning and long term memories. People are also often described as having likable personalities, being sensitive to others' emotions and as having a good sense of humour! 


There are some physical features associated with Fragile X, including a long narrow face with prominent jaw bones and ears. However, these are rarely obvious in young children. The lack of distinguishing features is one of the reasons that diagnosis can be delayed. You cannot tell that someone has Fragile X just based upon their appearance or behaviour. The only way to tell if someone has Fragile X Syndrome is to do a genetic test


You can also find out about how Fragile X Syndrome affects people by reading some of our members' family stories.