What causes Fragile X?
In 1991, scientists discovered the gene (called FMR1) that causes Fragile X. In individuals with Fragile X Syndrome, a defect in FMR1 (a full mutation) shuts the gene down. Like a defective factory, the FMR1 gene cannot manufacture the protein that it normally makes. Some indiviuals are carriers: they have a small defect in the FMR1 gene (called a premutation) but do not show symptoms of Fragile X. Fragile X is inherited. Carrier men (transmitting males) pass the premutation to all their daughters but none of their sons. Each child of a carrier woman has a 50% chance of inheriting the gene. The fragile X premutation can be passed silently down through generations in a family before a child is affected by the syndrome. A DNA blood test identifies both carriers and affected individuals. While the exact prevelance of Fragile X is unknown, recent studies indicate the statistics below: 1 in 2000 boys and 1 in 4000 girls are estimated to be affected Typical characteristics of Fragile X Syndr
