Fragile X syndrome is just one of many developmental disabilities . Because many persons affected by fragile X have autistic-like symptoms, it is often listed among the autism spectrum disorders. The National Fragile X Foundation is the oldest advocacy group on fragile X syndrome. This site contains a comprehensive overview of fragile X syndrome as well as summaries of the latest research from the biennial international conference it sponsors. Much of the information is of great practical value to parents and professionals alike.
Basic information is available in a number of other languages.
Another excellent source of information. This is by no means a comprehensive list, but contains sites that are particularly good or of personal interest. In English, French, and Portuguese Interessengemeinschaft Fragiles-X e. V. German Parents Group. Some translation from German to English.