Fragile X Info Series
Info series on FXS PDF cover

Fragile X Syndrome

An Overview for Families and Providers

You can download the PDF to print and share, and the full text is also on this page.

Fragile X is a group of conditions associated with changes in the Fragile X gene. The gene (also known by its scientific name of “FMR1”) can be typical, or it can exhibit a “premutation” or a “full mutation.” When a premutation or full mutation is present, it can result in a Fragile X-associated disorder. These include:

FXS

FRAGILE X SYNDROME

FXS is an inherited disorder affecting intellectual, behavioral, and social development. It occurs in both males and females who have a full mutation of the FMR1 gene.

FXTAS

FRAGILE X-ASSOCIATED TREMOR/ATAXIA SYNDROME

FXTAS is an adult onset (over 50 years of age) neurological disorder, more common and more severe in males. It causes tremors, memory, and balance problems in those with a premutation of the FMR1 gene. (Both males and females who have a premutation are also referred to as “carriers.”)

FXPOI

FRAGILE X-ASSOCIATED PRIMARY OVARIAN INSUFFICIENCY

FXPOI is a condition affecting ovarian function that can lead to infertility and early menopause in some female carriers.

THE FMRI GENE

The FMR1 gene can undergo changes that cause these Fragile X-associated disorders.

These changes affect a pattern of DNA called CGG repeats.

Typically, the FMR1 gene has up to 54 CGG repeats.

A premutation in the FMR1 gene results in 55–200 CGG repeats, and a full mutation in more than 200 CGG repeats.

The range of 45-54 is called the “gray zone.”

OTHER PREMUTATION CONDITIONS

Research is currently underway looking at various issues that may be seen in people with the premutation.

Characteristics of Fragile X Syndrome

The following physical, cognitive, and behavioral characteristics of Fragile X syndrome are usually more evident in males, but females can also demonstrate a range of features.

PHYSICAL FEATURES

MAY INCLUDE:

  • Large/protruding ears
  • Soft skin
  • Flexible joints—particularly fingers, wrists, elbows
  • Low muscle tone
  • Flat feet
  • Long face
  • Seizure disorder (epilepsy)

DIFFICULTIES

MAY INCLUDE:

  • Managing transitions to new schools or employment
  • Learning adult living skills such as transportation and using money
  • Managing emotional upsets and aggression
  • Making and sustaining friendships
LEARN MORE ABOUT FRAGILE X SYNDROME

BEHAVIORAL, INTELLECTUAL AND SOCIAL CHARACTERISTICS

MAY INCLUDE:

  • Speech and language delay
  • Motor delay (late crawling, walking, toileting)
  • Tactile defensiveness and sensory overload (high sensitivity to various fabrics/clothing, loud noises, crowds, food textures & tastes, etc.)
  • Hand-flapping, hand-biting
  • Poor eye contact/gaze aversion
  • Autism spectrum disorders
  • ADHD (attention deficit/hyperactive disorder)
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Treatment and Intervention

Research and clinical experience have shown that children with FXS may benefit from the following treatments and interventions:

  • Early intervention such as infant development therapy and special needs preschool.
  • Speech and occupational therapy, particularly sensory integration.
  • Behavioral Therapies
  • Special education (though many children with FXS are able to be “fully included” in an age appropriate classroom).
  • Medications for symptom-specific issues such as anxiety, ADHD, seizures, etc.
  • Fragile X clinic referral for consultation regarding educational and therapeutic strategies.
  • To see the latest studies and trials, visit MyFXResearch portal.
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Transition to Adult Services for Individuals with Fragile X Syndrome

Adolescents and adults with FXS also benefit from educational opportunities that help them acquire appropriate life skills. These programs can begin in high school and extend into adulthood, and should include education and guidance in matters of employment, social activity, recreation, independent living, and sexuality.

Transition to Adult Services Recommendations

Inheritance of FXS

The FMR1 gene is on the X chromosome. Males have one X and one Y chromosome; females have two X chromosomes. In females with a full mutation, their other, normal X often compensates for the FMR1 mutation. That frequently results in milder symptoms of FXS. In males the Y chromosome cannot compensate for the effects of the Fragile X mutation.

  • Both males and females can be FMR1 carriers and can pass the premutation on to their children.
  • Male premutation carriers will pass the premutation on to all their daughters and none of their sons.
  • Female premutation carriers have a 50% chance in each pregnancy to pass the premutation to their children of either gender. The risk of a premutation to expand to a full mutation is dependent on its number of CGG repeats.
  • Only premutations carried by women expand to the full mutation that causes Fragile X syndrome.
LEARN MORE ABOUT GENETICS & INHERITANCE
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Testing for FXS

Also see our Fragile X Info Series: Testing download.

  • Any individual who has unexplained developmental disabilities, speech delay, ADHD, autism, or learning disabilities should be tested for Fragile X.
  • The Fragile X test, also called the FMR1 DNA test, is not the same as a chromosome analysis or microarray, which examine all 46 chromosomes. However, a provider may order a number of tests in a child who exhibits unexplained delays in development. The test can be ordered by a genetic counselor or physician.
  • Genetic counseling is recommended for any individual or relative of someone who has a positive test result, or a relative diagnosed with any of the Fragile X-associated disorders. A physician can refer you to a local genetic counselor or you can find one at the National Society of Genetic Counselors. Also, the genetic specialist at the National Fragile X Foundation can assist you — call (800) 688-8765.
LEARN MORE ABOUT TESTING
Info series on FXS PDF cover

INFO SERIES
Fragile X Syndrome: An Overview for Families and Providers

An intro to Fragile X, including characteristics, inheritance, behaviors, interventions and treatments, and the associated disorders.

Download the PDF to print and share.

How We Can Help

The National Fragile X Foundation offers help for today and hope for tomorrow with personalized support, community, education, awareness, advocacy, and research.

GET YOUR FREE WELCOME PACKET

If you have specific questions about what to expect, treatments, clinics … well, just about anything, please email us at treatment@fragilex.org or call (800) 688-8765.

More from the Fragile X Info Series
VIEW ALL
Fragile X Info Series: Fragile X Syndrome: For Kids of All Ages
Fragile X Info Series: Fragile X Syndrome: Getting a New Diagnosis
Fragile X Info Series: Your In-Person Visit to a Fragile X Clinic
Fragile X Info Series: Females and Fragile X
Fragile X Info Series: Testing
Fragile X Info Series: Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS)
Fragile X Info Series: Fragile X-Associated Primary Ovarian Insufficiency
Fragile X Info Series: Siblings