Fragile X Syndrome: A-to-Z Guide from Diagnosis to Treatment to Prevention

Fragile X syndrome is a condition caused by a fragile area on the X chromosome. This section of the chromosome contains ‘repeats' in the genetic code.

Fragile X syndrome is the most common cause of mental retardation in boys.

What is fragile X syndrome?

Fragile X syndrome is a condition caused by a fragile area on the X chromosome. This section of the chromosome contains ‘repeats’ in the genetic code. Higher numbers of repeats is associated with more severe forms of the disease.

Who gets fragile X syndrome?

The number of repeats in a fragile X chromosome tends to remain constant when transmitted by a father but to increase each time it is transmitted by a mother. Those with 200 to 2000 repeats (or even more) have the symptoms of full-blown fragile X syndrome. Girls with fragile X syndrome have varying degrees of symptoms.

What are the symptoms?

The classic symptoms are mental retardation, large size, large testicles, and a long face with a prominent jaw and large ears. Often the eyes are pale blue.

Torticollis and cleft palate are more common in those with Fragile X.

These children also tend to be hyperactive and sometimes have some of the stereotypical movements associated with autism.

Cluttering is the name of their characteristic speech pattern. Like stuttering, cluttering is a speech disorder, but cluttering involves pauses in normal speech that are too short, too long, and in the wrong places. These may come from talking in fast spurts, or from not knowing what one wants to say. Corrections, revisions, and interjections are common. (People who stutter know what they want to say but have difficulty getting the words out.)

Is fragile X syndrome contagious?


How long does fragile X syndrome last?

This is a lifelong condition.

How is it diagnosed?

Fragile X is diagnosed with specific chromosome testing.

How is it treated?

There is no cure for fragile X syndrome. Therapy is aimed at helping people with fragile X reach their full potential.

How can it be prevented?

Once a baby is conceived with fragile X, nothing can change that. Timing of childbearing may make some difference in inheritance. We do know that women who are carriers are more likely to have had older fathers.

Prenatal genetic testing is now available to see if a woman carries the Fragile X permutation, which puts her at risk for having a baby affected by Fragile X. During the pregnancy, there are additional ways to confirm whether the baby is affected, including chorionic villus sampling and amniocentesis. A newer screening tool involves analyzing strands of fetal DNA in the mother’s blood and may be done as early as 10 weeks into the pregnancy.

Martin-Bell syndrome, Marker X syndrome, Cluttering

Last medical review on: January 04, 2014
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Dr. Greene is a practicing physician, author, national and international TEDx speaker, and global health advocate. He is a graduate of Princeton University and University of California San Francisco.
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