Fragile X Syndrome

What is Fragile X Syndrome?

Fragile X syndrome is also known as Escalante’s syndrome and Martin-Bell syndrome and is a genetic condition that causes intellectual disability, learning and behavioral problems, and different physical characteristics.

The condition affects more men than women. Women with Fragile X syndrome tend to have less severe intellectual disabilities than their male counterparts. Almost half of all children with Fragile X syndrome also have a diagnosis of autism. A definite diagnosis of the condition is made using a DNA blood test called the FMR1 DNA test. More than 80% of males with Fragile X syndrome have an IQ of 75 or less. About one in 3,600 to 4,000 males is affected by the full mutation of the FMR1 gene while one in 4,000 to 6,000 females is affected by the full mutation of the FMR1 gene.

What are the Symptoms of Fragile X Syndrome?

The syndrome can cause impulsiveness, seizures, depression, hyperactivity, an elongated face, hand-biting, poor eye contact, problems sleeping, attention deficit, stuttering, anxiety, difficulty learning new information or skills, flat feet, a large forehead or ears, large testicles (in males), delay in learning to talk, walk, and sit when compared to children of the same age.

Fragile X Syndrome Causes

Fragile X syndrome develops when there’s a mutation or defect in a gene called FMR1 that’s found on the X chromosome. There are two kinds of sex chromosomes: X and Y. Men have both the X and Y chromosomes while women have a pair of X chromosomes.

The mutation, or defect, prevents the FMR1 gene from making a protein known as FX mental retardation 1 protein that’s needed by the brain to work properly. This protein is essential for making and maintaining the communication between cells in both the nervous system and brain. A defect in the FMR1 gene makes the body produce too little or none of the protein, which often causes fragile X symptoms.

Not everybody with the defective FMR1 gene has fragile X symptoms, as the body can still be able to produce FX mental retardation 1 protein.

Both boys and girls may be affected, but boys are likely to be affected more severely as they have just one X chromosome. One can have FXS even if his or her parents don’t have it.

How is Fragile X Syndrome Treated?

Fragile X syndrome cannot be cured.

Treatment includes

Medications prescribed for attention deficit disorder may also be given for the symptoms of Fragile X syndrome. Melatonin may be prescribed for sleep disorders, Aripiprazole and antipsychotics may be given to individuals with extreme behaviors, stimulants may be prescribed for ADHD, and Clonidinemay be given for anxiety disorders.

Therapies such as language, speech, behavioral, and physical may be employed to help the individual reach their full potential.

Fragile X Syndrome Prevention

Once a child is conceived with FXS, this cannot be changed. The timing of conception can make a difference in inheritance. It’s common knowledge that older fathers are more likely to sire women who carry fragile X syndrome.

Nowadays, there’s prenatal genetic testing available to determine whether a woman carries FXS, which increases her risk of giving birth to a baby suffering from fragile X. During pregnancy, there are other methods to test whether a baby is affected, such as amniocentesis and villus sampling. There’s also a new screening machine that analyzes strands of DNA in the fetus and this can be done from 10 weeks of the pregnancy.

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Last Reviewed:
October 06, 2016
Last Updated:
June 14, 2018
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