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Fragile X Syndrome

What is fragile X syndrome?

Fragile X syndrome is an inherited disorder. It can cause hyperactivity, learning problems, and emotional problems. It can also cause mental retardation and autism. Some children with fragile X have normal IQs. This disorder is the most common known cause of inherited mental retardation and affects both males and females.

What is the cause?

More than 100 trillion cells make up the human body. Inside each cell are genes. Genes contain the information used by other parts of the cell to make proteins, the body's building blocks. Each protein does a specific job.

If the information in a gene is changed, the cell may not be able to make that protein. Or it may not be able to make a form of the protein that the body can use. Fragile X occurs because the FMR1 gene cannot make normal amounts of usable Fragile X Mental Retardation Protein, or FMRP.

A person with nearly normal levels of FMRP usually has mild or no symptoms, while a person with very little or no normal FMRP has more severe symptoms. Usually boys are affected more severely than girls.

What are the physical, behavioral, and health concerns?

  1. Physical characteristics

    Boys affected by fragile X syndrome often have large ears, a large head, a broad forehead, extra flexible finger joints, a high palate, soft skin, and flat feet. During puberty, boys usually develop large testicles (called macroorchidism) and a longer face than most people. Most children with fragile X syndrome look normal.

    Girls may also have physical features linked to fragile X syndrome, particularly large ears, flexible finger joints, and flat feet.

  2. Health concerns

    In general, children with fragile X syndrome do not have a lot of medical complications. The health problems they may have include:

    • frequent ear infections
    • seizures (in about 20% of children and adults with fragile X)
    • strabismus, a weak eye muscle, occurs in some children with fragile X
    • mitral valve prolapse, a heart valve problem, which occurs in about 50% of adults with fragile X
    • a hernia or joint dislocation.
  3. Behavioral characteristics

    The major problems with fragile X syndrome involve behavior and slow development. Most girls with fragile X syndrome have learning problems and a short attention span along with shyness, social anxiety, and moodiness. About 30% of girls with fragile X syndrome are mentally retarded. The majority have significant learning disabilities. Most males with fragile X syndrome are mentally retarded, meaning that their IQs are below 70.

    Children with fragile X are usually extra sensitive to new sights, sounds, smells, touches, or changes in their routine. They are usually anxious and often have tantrums.

    For most boys and some girls with fragile X, the activity level is high and the attention span is short. Language development is especially slow. Most boys do not talk much by age 3. Unusual behaviors commonly develop by 3 years of age. These are sometimes called autistic-like behaviors. Some of these behaviors are hand flapping, hand biting, poor eye contact, excessive chewing on clothes, and pulling away from touch. These children may ask questions over and over again even after hearing the answer.

    Approximately 20% to 35% of children with fragile X have autism. Children with autism have trouble with social interaction, language, and repetitive or ritualistic behavior.

    Irritability and moodiness are a problem for most people with fragile X. Moodiness combined with anxiety leads to aggressive behavior in about one-third of adolescent boys and men with fragile X.

  4. Strengths of children with fragile X

    Children with fragile X syndrome have many strengths, including their social abilities (although shyness is common); a wonderful sense of humor; an excellent memory for people, events, and directions; intense interests; and outstanding imitation skills.

What is the treatment?

There is no cure for fragile X syndrome, but many treatments are available.

  1. Therapy

    If your child is diagnosed in infancy, your provider will discuss infant stimulation programs. Developmental preschool programs are helpful for children under 5 years of age.

    Speech, language, occupational, and physical therapy are very important to help your child develop motor skills and language. Sensory integration therapy can be helpful for behavioral problems. The therapist will teach physical calming techniques, such as deep pressure back rubs and joint compression, which may help to calm behavior outbursts or tantrums at home.

    Your provider or psychologist can help you set up a behavior program at home that includes consistent structure, regular routines, and positive feedback.

    If your child has autism and fragile X syndrome, then an applied behavioral analysis (ABA) or similar program may be helpful.

  2. Education

    Your child's special education program in school should include time in the regular classroom and individual help from a special education teacher. A tutor can help with assignments for weak academic areas. Speech and language therapy, occupational therapy, and computer use may also help you child learn. Your school and health care provider can help you arrange these services and the proper kinds of therapy when needed.

  3. Medical care and medicines

    Most children with Fragile X do not have serious medical problems. Your provider will treat ear infections, heart murmur, seizures, or other problems as needed.

    Your provider may prescribe medicines that can improve poor attention span, hyperactivity, tantrums, aggression, anxiety, obsessive thinking, or other behavioral or emotional problems. Medicine may be used with other kinds of treatment. Such medicines are used for a trial period and are continued only if they help. If your child has a side effect to the medicine, call your provider.

Genetic Tests

A special type of blood text called an FMRI-DNA test should be done to confirm the diagnosis of fragile X syndrome.

The DNA test analyzes the structure of the fragile X gene in great detail. All people have the fragile X gene and it normally produces the fragile X protein, which is very important for normal brain development. Most people have between 5 to 44 CGG repeats in their fragile X gene. Carriers, on the other hand, have between 55 to 200 repeats. Carriers usually have a normal IQ, but they may have problems with early menopause, anxiety, learning problems, or even autism. Some male carriers who are over 50 years old develop tremors, balance problems, numbness or pain in the legs, and sometimes dementia.

People with greater than 200 repeats are significantly affected by fragile X syndrome. The DNA test can check how many repeats your child has.

Because fragile X syndrome is a genetic disorder, you should consider this during future pregnancies. Talk with your genetic counselor or health care provider about prenatal diagnosis and new reproductive technologies.

Parent Support Groups

If your child is diagnosed with fragile X, it is often helpful to talk to another family with a child who is similarly affected. The National Fragile X Foundation, at 1-800-688-8765 or has a list of resource centers, parent support groups, and educational materials. You can call them for educational information and the phone number of a parent nearest you.

Children with fragile X syndrome are not easy to raise, and parents need to have personal time and recovery time. If you feel overwhelmed, depressed, or anxious, talk with your provider. He or she can help you. You can help your child best if you take care of your own emotional and physical health.

Written by Randi Hagerman, MD, Fragile X Research Chair in Pediatrics and Medical Director of the MIND Institute, UC Davis Medical Center.
Published by McKesson Provider Technologies.
Last modified: 2006-10-26
Last reviewed: 2006-08-25
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
Copyright 2006 McKesson Corporation and/or one of its subsidiaries. All Rights Reserved.
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