Fragile X

The Fragile X Syndrome topic includes research on the genetics, diagnosis, and treatment of fragile X syndrome, a genetic developmental disorder. Fragile X, which affects behavior and ability to learn, can be more severe among males because they have only one copy of the X chromosome. All racial and ethnic groups are affected as well.

Most cases of fragile X are caused by a change in the FMR1 gene, where a DNA segment known as the CGG triplet repeat, is expanded. Normally, the CGG segment is repeated from 5 to about 40 times, but in people with fragile X syndrome the CGG segment is repeated more than 200 times. This lengthened CGG segment silences the FMR1 gene and prevents it from producing a protein that prevents the syndrome.