Who is at risk for Fragile X syndrome?
The inheritance of fragile X syndrome is complex. Expansion of the fragile X premutation into a full mutation has only been reported when the premutation is passed on by the mother.2,3 Therefore, a woman that is a carrier of fragile X syndrome has a 50% chance with each pregnancy to pass on the unstable fragile X gene.3 The chance that the unstable gene will expand into a full mutation varies with the repeat size.
