Fragile X syndrome (FXS) is a genetic condition that causes intellectual disability, behavioral and learning challenges, and various physical characteristics. Though FXS occurs in both genders, males are more frequently affected than females, and generally with greater severity.

  • 46% of Fragile X males have autism
  • 16% of Fragile X females have autism
  • 1-6% of individuals with autism, also have Fragile X

FXS is inherited, which means it is passed down from parent to child. The changes in the gene can become greater when passed from mother to child. So, a woman who has no symptoms related to Fragile X can have a child affected with FXS. A male carrier can only pass the premutation, and will pass it to all of his daughters, but none of his sons. FXS affects people of all ethnicities, races, and socio-economic backgrounds. Fragile X syndrome is named because of the appearance of the X chromosome where the gene mutation occurs, not because individuals with the FMR1 mutation are in any way “fragile”.

When someone is unfamiliar with FXS and is interacting for the first time with an individual who has been diagnosed with it, Fragile X individuals may appear to have behavioral traits that are similar to someone who has been diagnosed with autism. This comparison is especially true in children who have Fragile X Syndrome.


Photo of Family with green shirts supporting the Fragile X annual walk