Symptoms usually include:
- intellectual disabilities, ranging from mild to severe
- attention deficit and hyperactivity, particularly in young children
- anxiety and unstable mood
- autistic behaviors
- sensory integration problems, such as hypersensitivity to loud noises or bright lights
- speech delay, with expressive language more severely affected than receptive language
- seizures (epilepsy) affect about 25% of people with Fragile X
These features may be hard to recognize in babies and young children, but sometimes become more apparent with age.
- long face, large prominent ears, flat feet
- hyperextensible joints, especially fingers
- low muscle tone
- males may have large testes, after puberty
Boys are typically more severely affected than girls. While most boys have mental retardation, only one-third to one-half of girls have significant intellectual impairment; the rest have either normal IQ or learning disabilities. Math is often a particular challenge for girls. Emotional and behavioral problems are common in both sexes.
About 30% of boys with fragile X meet full criteria for autism. Most boys and some girls have some symptoms of autism, but many tend to be very social and interested in other people.