What are the symptoms of Fragile X syndrome?

People with Fragile X do not all have the same signs and symptoms, but they do have some things in common. Symptoms are often milder in females than in males.

  • Intelligence and learning. Many people with Fragile X have problems with intellectual functioning.
    • These problems can range from the mild, such as learning disorders or problems with mathematics, to the severe, such as an intellectual or developmental disability.
    • The syndrome may affect the ability to think, reason, and learn.
    • Because many people with Fragile X also have attention disorders, hyperactivity, anxiety, and language-processing problems, a person with Fragile X may have more capabilities than his or her IQ (intelligence quotient) score suggests.
  • Physical. Most infants and younger children with Fragile X don’t have any specific physical features of this syndrome. When these children start to go through puberty, however, many will begin to develop certain features that are typical of those with Fragile X.
    • These features include a narrow face, large head, large ears, flexible joints, flat feet, and a prominent forehead.
    • These physical signs become more obvious with age.
  • Behavioral, social, and emotional. Most children with Fragile X have some behavioral challenges.
    • They may be afraid or anxious in new situations.
    • They may have trouble making eye contact with other people.
    • Boys, especially, may have trouble paying attention or be aggressive.
    • Girls may be shy around new people. They may also have attention disorders and problems with hyperactivity.
  • Speech and language. Most boys with Fragile X have some problems with speech and language.
    • They may have trouble speaking clearly, may stutter, or may leave out parts of words. They may also have problems understanding other people’s social cues, such as tone of voice or specific types of body language.
    • Girls usually do not have severe problems with speech or language.
    • Some children with Fragile X begin talking later than typically developing children. Most will talk eventually, but a few might stay nonverbal throughout their lives.
  • Sensory. Many children with Fragile X are bothered by certain sensations, such as bright light, loud noises, or the way certain clothing feels on their bodies.
    • These sensory issues might cause them to act out or display behavior problems.
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