The prevalence of fragile-X syndrome in an institution for people with learning disability

The prevalence of Fragile-X syndrome in those with learning disability has been reported. There is little agreement regarding the prevalence rate which varies between 0% and 16%. We report a study investigating the prevalence of Fragile-X syndrome in two institutions for those with learning disability, using DNA testing. We found a rate of 0.7%, which is one of the lowest record rates. We also found that physical signs could be used as a reliable discriminator to determine those likely to have the disorder. We conclude that indiscriminate mass screening of those with learning disability for the Fragile-X syndrome is probably not useful because, in adults, physical signs and a family history of learning disability can predict those likely to have the disorder.