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Genetics of Hurler Syndrome

written by: R. Elizabeth C. Kitchen•edited by: Emma Lloyd•updated: 7/17/2010

Is there a chance that Hurler syndrome runs in your family? If so, read on to learn more about this genetic disorder.

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    Hurler syndrome is one of a group of diseases referred to as mucopolysaccharidoses, or MPS. This inherited disease is rare and affects the metabolism. This genetic disorder causes the patient to not be able to break down long chains of glycosaminoglycans, a type of sugar molecule. If there is a family history of this genetic disorder, parents should consider having genetic counseling prior to trying to have children. This disorder has a poor prognosis for most patients, therefore, it is a good idea for aspiring parents to know if there is the possibility that their future children could inherit Hurler's syndrome.

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    How Common is this Genetic Disorder?

    The severe MPS I affect about one in 100,000 newborn babies. Attenuated MPS I affects about one in 500,000 newborn babies, making is less common.

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    Genetics of Hurler Syndrome

    Hurler syndrome This genetic disorder is caused by an IDUA gene mutation. IDUA enzyme function is either completely eliminated or greatly reduced when there are mutations in the IDUA gene. Children inherit this condition from a parent, who most often does not have any symptoms, in an autosomal recessive pattern.

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    Symptoms of Hurler Syndrome

    The symptoms of this genetic disorder most often begin between three and eight years of age. The facial symptoms associated with this disorder can start to be more obvious during the child's first two years of life. The other symptoms of Hurler's syndrome include:

    • Bones in the spine are abnormal
    • Cloudy corneas
    • Halted growth
    • Joint disease and joint stiffness
    • Low nasal bridge with coarse, thick facial features
    • Claw hand
    • Deafness
    • Heart valve problems
    • Mental retardation that becomes worse as time passes
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    Diagnosing this Genetic Disorder

    Hurler syndrome can be diagnosed using a variety of diagnostic tests. These include:

    • An, EKG, or electrocardiogram, is done to measure the heartbeat's electrical activity.
    • Urinalysis can be done to look for extra mucopolysaccharides.
    • An x-ray of the spine can be done, most often to look for any abnormal spinal bones.
    • Genetic testing can be done for the alpha-L-iduronidase gene (IDUA).
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    How is Hurler Syndrome Treated?

    This genetic disorder is not curable, but there are treatments available to help alleviate some of the symptoms. These include:

    • Enzyme replacement therapy is done to put a working form of the enzyme that is missing into the body.
    • Bone marrow transplant has had mixed results, but has been done for several Hurler's syndrome patients.
    • The organs that are affected will ultimately determine the other treatments used.

    This genetic disorder has a poor prognosis. Children who have this disorder end up experiencing nervous system problems, which can result in dying young.

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    Genetics Home Reference. (2010). Mucopolysaccharidoses Type I. Retrieved on July 15, 2010 from Genetics Home Reference:

    Medline Plus. (2009). Hurler Syndrome. Retrieved on July 15, 2010 from Medline Plus:

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    Image Credits

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