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What is Fragile X Syndrome?

Fragile X syndrome (also known as Martin-Bell syndrome, Escalante’s syndrome or simply FXS) is a genetic disorder and it is the most common cause of inherited mental disability. It is more common in boys than in girls.

The cognitive effects of fragile X syndrome vary from person to person, and range from mild learning disabilities to severe mental retardation. Fragile X is one of the most common known reasons for autism and its associated social, emotional, behavioral and language disturbances. For example, people with fragile X syndrome may have problems interpreting social cues like body language, and experience shyness, social anxiety and delays in language and speech development. They may also dislike strong stimuli such as loud noises and bright lights, and there is also an increased risk of their developing ADHD, depression and obsessive disorders.

In addition to its effects on intellectual ability, teenage boys and men with fragile X syndrome have a number of distinctive physical traits including long faces, ears that stick out, poor muscle tone, soft skin, flat feet, double joints and larger than normal testicles.

Fragile X syndrome is actually part of a family of disorders related to the same gene, the other two members of the family being fragile X-associated primary ovarian insufficiency (FXPOI) and fragile X-associated tremor ataxia syndrome (FXTAS). Women with FXPOI tend to experience infertility and early menopause. FXTAS tends to occur in males over the age of 50; its symptoms include memory loss, tremor, mood swings and dementia. Not surprisingly, it is often confused with Alzheimer’s disease and Parkinson’s disease.

Fast Facts about Fragile X Syndrome

  • Fragile X syndrome is a genetic disorder associated with an excess of DNA in the FMR1 gene in the X chromosome
  • It is more common in males than in females
  • Fragile X syndrome varies in severity and causes mild to severe cognitive impairment, autism and behavioral disorders
  • Boys and men with fragile X syndrome have a distinctive physical appearance, including a long face, protruding ears, poor muscle tone and flat feet
  • There are two related disorders which are also associated with problems in the FMR1 gene: fragile X-associated tremor/ataxia syndrome (FXTAS) and fragile X-associated primary ovarian insufficiency (FXPOI)
  • It is possible to be a carrier without having full-blown fragile X syndrome
  • If you have a family history of fragile X syndrome and want to start a family of your own, you may want to consider undergoing genetic counseling to find out the likelihood of your children being affected

Causes of Fragile X Syndrome

Fragile X syndrome got its name because when examined under the microscope, part of the X chromosome of an affected person seems to be fragile or broken.

The reason for this apparent fragility is that one of the X chromosome’s genes, called FMR1 (short for Fragile X Mental Retardation 1) has a number of repeated sequences in its DNA. The greater than normal amount of DNA in the FMR1 gene is what causes its unusual “broken” appearance. The number of repeated sequences varies from sufferer to sufferer, hence the variation in severity of symptoms from person to person.

The job of the FMR1 gene is to produce a protein that is used in brain development. In people with fragile X syndrome, the FMR1 gene doesn’t manufacture enough of this protein, hence the mental impairment.

Risk Factors for Fragile X Syndrome

Boys are more likely to display symptoms of fragile X syndrome than girls. This is because boys only have one X chromosome, whereas girls have two X chromosomes, so the chances are that girls will have one X chromosome that works normally.

Men with fragile X syndrome will pass it on to their daughters, who may or may not display symptoms of the disease. Women with a fragile X chromosome can pass it on to both sons and daughters, who have a 50 percent chance of inheriting the chromosome.

Symptoms of Fragile X Syndrome

Fragile X syndrome has a range of effects on mental and emotional functioning. The cognitive (mental) effects of fragile X syndrome vary from mild learning difficulties to severe mental retardation. People with fragile X syndrome are often autistic and therefore show signs of social, emotional, behavioral and language disturbance, like difficulty interpreting social cues (e.g. body language and facial expression), social anxiety, shyness and delays in speech and language development. They may also dislike bright lights, loud noises and being touched, and they may show behavioral disorders such as ADHD, depression, aggression and obsessiveness.

Teenage boys and men with fragile X syndrome may have the following physical traits: long faces, ears that stick out, poor muscle tone, soft skin, flat feet, double joints and larger than normal testicles.

Diagnosing Fragile X Syndrome

Symptoms such as learning difficulties and signs of autism will be the first indications that a person has fragile X syndrome. However, other disorders can result in the same symptoms and to confirm the diagnosis, a DNA test must be done to determine the number of repeats in the DNA sequence on the FMR1 gene.

Treatment Options for Fragile X Syndrome

Fragile X syndrome doesn’t have a cure. However, the right education and therapy can be of great benefit – the earlier the better. This can take the form of speech and language therapy, help with motor skill acquisition and sensory integration, and the teaching of everyday life skills. Sometimes drugs can be used to help with the behavioral problems and mood disorders that are associated with Fragile X syndrome.

Prevention of Fragile X Syndrome

There is no known method of preventing fragile X syndrome. If you are planning a family and you know you are a carrier or you have a family history of fragile X syndrome, you may wish to consider genetic counseling to find out the likelihood that your children will inherit the condition.

Coping with Fragile X Syndrome

  • Children whose development is disturbed by fragile X syndrome are eligible for specialized educational services, delivered in the US via an Individualized Education Plan.
  • Some children with fragile X syndrome benefit from the more relaxed and less socially intense environment offered by home schooling.
  • Fragile X syndrome can have profound effects on a person’s mental function but it does not necessarily result in a shorter lifespan. Parents and other relatives of individuals with fragile X syndrome may therefore need to make long-term plans for their welfare, financial and otherwise.
  • Adults with fragile X syndrome may benefit from assisted/community living schemes. They can often hold down jobs, but may prefer to work in a structured, predictable environment rather than one involving a lot of uncertainty.

Where to Find More Information:
National Fragile X Foundation
FRAXA