Fragile X Syndrome is now recognized as the leading hereditary cause of developmental and learning disabilities. Males are usually more severely affected than females.
Boys are typically more severely affected than girls.
Emotional and behavioral problems are common in both sexes. Fragile X is one of the most common inherited diseases. It affects all races and ethnic groups. Like a defective factory, the FMR1 gene cannot manufacture the protein that it normally makes. The fragile X premutation can be passed silently down through generations in a family before a child is affected by the syndrome.