What Is Fragile X Syndrome

Autism and Fragile X

What is fragile X syndrome? Some people diagnosed on the autism spectrum have fragile X as well. However, the conditions do not always coexist. The disorder is the only cause for autistic traits that has been established.

What Is Fragile X Syndrome

Fragile X is inherited as a genetic mutation on the X chromosome. The condition results in a number of symptoms that exist on behavioral, physical, cognitive and developmental levels. This genetic condition does have physical characteristics, unlike autism, which has no real physical characteristics. Like autism, FXS has a wide range of severity, ranging from mild to severe.

Symptoms of FXS

The symptoms of fragile X vary according to the individual. Some people carry the gene, having no symptoms or very mild signs of FXS. It helps to organize the condition's population in order to evaluate the symptoms effectively. Since the disorder occurs on the X chromosome, and males have only one while females have two, gender is a significant factor to consider.

In addition, some people may carry altered genes without having a full mutation. Two groups stem from the male and the female populations, full mutations and premutations.

Fragile X and Gender

FXS affects males more profoundly than females, resulting in cognitive delays and disabilities. Macroorchidism (enlarged testicles) may be present. Not every male with the condition has autism, just as not all males share all of the behavioral and physical characteristics associated with FXS. Females affected by the disorder may have many of the same characteristics seen in males. Some females, including carriers, may experience primary ovarian insufficiency, a condition in which the ovaries stop functioning before the woman's 40th birthday. Roughly, one-third of females with FXS have considerable cognitive disabilities. Most experience the behavioral and physical characteristics less severely than males do.

Full Mutation

Full mutations lead to the most significant symptoms of fragile X syndrome. Females who have full mutations may exhibit some of the following traits:

  • Health
    • Increased risk for early menopause
    • Increased risk for ovarian failure
    • Mitral valve prolapse
    • Hyper-mobility in joints
  • Physical
    • Flat feet
    • Elongated face
    • High arched palate
    • Big ears
  • Cognition
    • No significant cognitive disability
    • Visual-spatial problems
    • Difficulty with problem-solving skills
    • Poor planning ability
    • Poor organization skills
    • Problems with visual memory
    • Difficulties in math
  • Social
    • Trouble adapting to new environments
    • Difficulty interpreting nonverbal communication
    • Anxiety
    • Depression
    • Shyness

    In spite of the obstacles, adequate emotional and social development is apparent in females with full mutation of the X chromosome. The condition affects males more drastically. Symptoms include but are not limited to:

  • Health
    • Hyper-mobility in joints
    • Double jointed thumbs
    • X-associated tremor ataxia syndrome (FXTAS)
    • Seizure disorder
    • Eye problems
    • Skin problems
    • Heart conditions
  • Physical
    • Prominent forehead and/or chin
    • Flat feet
    • Elongated face
    • High arched palate
    • Big ears
    • Flat feet
    • Elongated face
    • High arched palate
    • Big ears
  • Cognitive
    • Significant cognitive delays
    • Borderline to profound mental retardation
  • Behavioral
    • Stereotyped repetitive movements associated with autistic disorders
    • Hyperactive
    • Tantrums
  • Social
    • Poor eye contact
    • Easily distracted
    • Impulsive
    • Perseverative speech
    • Difficulty adapting to new situations

    Sensory problem may occur as well in both males and females with full mutations. Sensory integration therapy can be effective for treating the processing difficulties.


X-associated tremor ataxia syndrome is a neurological condition that appears later in life, more often in males than in females. The neurological problem causes tremors, intellectual decline and unstable mood. FXTAS was often mistaken for other conditions including Parkinson's, Alzheimer's, and dementia.

Premutation FXS

Both males and females can carry the genetic mutation on the X chromosome without displaying any apparent symptoms. Traditionally, carriers are individuals do not show symptoms. However, in FXS, this is not the case. A carrier can display the following signs of a problem on the X chromosome:

  • Males
    • X-associated tremor ataxia syndrome (FXTAS)
    • Very mild physical features of fragile X
    • Autism
    • Developmental disorders
    • ADHD
  • Females
    • Premature ovarian failure
    • Average IQ
    • X-associated tremor ataxia syndrome (FXTAS)
    • Difficulty attending to more than one task at a time
    • Score lower on math and vocabulary tests
    • Shyness
    • Social anxiety
    • Depression

    It is important to note that depressed feelings may stem from parenting a child with the disorder, making it questionable whether the mood disorder stems from genetic or situational factors.

Help and Information

The National Fragile X Foundation offers a free brochures detailing different topics related to the condition:

  • New diagnosis
  • Research
  • General information
  • FXS in females
  • Speech therapy
  • Occupational therapy
  • Behaviors
  • Testing
  • Social Security help
  • Siblings
  • Toilet training

Fragile X syndrome shares some characteristics with autism, and in some cases, the conditions coexist in the same individual. Just as apraxia and autism have deep connections, the two are distinct disorders with their own specific criteria for diagnosis.

Was this page useful?
Related & Popular
What Is Fragile X Syndrome