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Understanding the Basics: Fast Facts About Fragile X Syndrome

Understanding the Basics: Fast Facts About Fragile X Syndrome

If you’ve newly met someone with Fragile X syndrome (FXS)—whether he or she is an immediate or distant family member, a friend or part of a friend’s family, a co-worker, a neighbor, or someone else—you may realize you don’t know much about this intellectual and developmental disability (IDD). So, here are some introductory facts about Fragile X syndrome to help you better understand it.

Basic Facts About Fragile X Syndrome

  • Fragile X syndrome is a genetic disorder. Everyone has an FMR1 gene on their X chromosome, and it usually makes the FMRP protein; however, in people with FXS, the gene does not produce this protein.
  • The FMRP protein helps regulate the production of other proteins and plays a role in the development of synapses (which facilitate communication between nerve cells).
  • The FMR1 gene was identified in 1991.
  • The exact number of individuals with FXS is unknown, but it’s estimated that around 1 in 4,000 males and 1 in 6,000 to 8,000 females have this disorder with the full mutation of the FMR1 gene.
  • There is a milder form of this mutation, and people with it are said to have an FMR1 gene premutation. Ususally, these individuals have mild physical and sometimes emotional symptoms of Fragile X syndrome, but they do not have intellectual impairment.
  • FXS is the most common form of inherited intellectual disability in males, and a significant cause in females.
  • Approximately 1 in 259 women carry Fragile X and can pass it on to their children; approximately 1 in 800 men carry it, and their daughters will be carriers too.
  • A mother who carries the Fragile X premutation has a 50% chance of passing it to each of her children, who will either be carriers or will have FXS. A father who carries the premutation will pass it to all his daughters but none of his sons; these daughters are carriers but will not have FXS.
  • The Fragile X premutation can be passed on silently through generations before a child manifests the syndrome.
  • Affected females tend to have milder FXS symptoms than affected males.
  • Signs and symptoms of Fragile X syndrome may include developmental delays, low IQ, learning disabilities, difficulty focusing, lack of eye contact, anxiety, hand flapping, impulsiveness, hyperactivity, stuttering or other speech problems, sensory sensitivity, short stature, elongated face or jaw, large ears, prominent forehead, unusually flexible fingers, flat feet, and enlarged testicles after puberty in males.
  • Most affected males have mild to severe intellectual impairment; only about one-third of affected females have intellectual impairment, and it’s generally mild. Read more about early signs of intellectual disability here.
  • Autism spectrum disorder (ASD) occurs at a higher rate in people with FXS, manifesting in about one-third of people with FXS.
  • Approximately 15% of males and 5% of females with FXS experience seizures.
  • People with FXS have their own personalities, talents, strengths, likes and dislikes, and other unique characteristics just as people without it do.
  • Many individuals with Fragile X syndrome have a great memory.
  • This IDD occurs in people of all races, ethnicities, and economic levels.
  • There is no cure for Fragile X syndrome. However, a variety of therapies and medications can be used to manage many of the symptoms and help individuals realize their full potential.
  • Gene therapy, FMR1 gene replacement therapy, and gene activation research are ongoing and will hopefully lead to improved treatment, a cure, or effective prevention of FXS.
  • If you have a relative who’s been diagnosed with Fragile X syndrome, you should be tested to see if you’re a carrier. A blood test is used for diagnosis.

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