Fragile X Syndrome: Symptoms & Signs

Medically Reviewed on 6/12/2020

Fragile X syndrome is the most common form of inherited mental disability. The intellectual disability is more pronounced in males with the condition because all affected males have intellectual deficiency. Affected females may have mental impairment, learning deficiencies, or normal IQ.

Signs and symptoms of Fragile X syndrome can include

  • deficiencies in intelligence and learning (low IQ),
  • long face or jaw,
  • enlarged testicles in males,
  • short stature,
  • anxiety,
  • stuttering,
  • disorganized speech,
  • balance problems, and
  • sensitivity to certain stimuli like sounds.

Other associated signs and symptoms can include loose, flexible joints, heart murmur, flatfeet, hernia, frequent ear infections, a large forehead or large head, and hyperextensible joints.

Causes of fragile X syndrome

A change in a single gene, the fragile X mental retardation 1 (FMR1) gene found on the X chromosome, causes this genetic disorder.

Other fragile x syndrome symptoms and signs

  • Anxiety
  • Balance Problems
  • Deficiencies in Intelligence and Learning (Low IQ)
  • Disorganized Speech
  • Enlarged Testicles in Males
  • Flatfeet
  • Frequent Ear Infections
  • Heart Murmur
  • Hernia
  • Hyperextensible Joints
  • Large Forehead or Large Head
  • Long Face or Jaw
  • Loose, Flexible Joints
  • Sensitivity to Certain Stimuli Like Sounds
  • Short Stature
  • Stuttering

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Jameson, J. Larry, et al. Harrison's Principles of Internal Medicine, 20th Ed. New York: McGraw-Hill Education, 2018.