Fragile X syndrome can present itself in a variety of ways and in varying degrees. Some individuals experience significant challenges, while the impact on others is so minor they may never be diagnosed.

Symptoms can include:

  • Intellectual impairment to varying degrees
  • Delayed and abnormal speech
  • Attention deficit hyperactivity disorder
  • Anxiety and unstable moods
  • Autism in 20-25% of people
  • Long face, large ears, flat feet
  • Hyperextensible joints, especially fingers
  • Seizures (epilepsy) in about 25% of people

The effect on boys tends to be more severe. Most boys have mental impairment and have some symptoms of autism.

Girls generally exhibit a milder form of Fragile X because they have two X chromosomes — one that works properly and one that doesn’t. As a result, females are able to produce enough of the FMRP to fill most of the body’s needs, but not all. Autism is less common in girls and only one-third to one-half of girls have significant intellectual impairment. The rest have either normal IQ and/or learning disabilities.