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Genetics of Lesch-Nyhan Syndrome

written by: R. Elizabeth C. Kitchen•edited by: Emma Lloyd•updated: 6/30/2010

Is your child affected by Lesch-Nyhan syndrome? If so, read on to learn more about this disorder and the genetics of Lesch-Nyhan syndrome.

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    This genetic disorder that affects how the body breaks down and builds purines. Purines are naturally occurring in the human body's tissues and they aid in making up the body's genes and DNA. Boys are most often affected by Lesch-Nyhan syndrome.

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    How Common is this Genetic Disorder?

    Approximately one in 380,000 people are affected by Lesch-Nyhan syndrome.

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    Genetics of Lesch-Nyhan Syndrome

    Lesch-Nyhan Syndrome HPRT1 gene mutations are responsible for causing this genetic disorder. When this gene is mutated, the patient's hypoxanthine guanine phosphoribosyltransferase enzyme is either severely lacking or completely missing. This enzyme is essential for recycling purines and when it is gone or severely lacking, uric acid builds up at abnormally high levels within the body. Lesch-Nyhan is inherited in an X-linked recessive pattern.

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    Symptoms of Lesch-Nyhan Syndrome

    When children experience excessive uric acid building up in their body, some of their joints will develop a gout-like swelling. In some cases, bladder stones and kidney stones will develop due to the high levels of uric acid.

    Males with this genetic disorder will have delayed motor development with subsequent sinuous, bizarre increased deep tendon reflexes and movements. A striking characteristic of this disorder is self-destructive behavior in the form of chewing off one's own lips and fingertips, if the patient is not restrained. How this enzyme deficiency causes these problems is unknown.

    Complications can also occur. These can include a progressive, severe disability. This complication is likely.

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    Diagnosing this Genetic Disorder

    In some cases, there is a family history of Lesch-Nyhan syndrome and if there is, the doctor should be made aware of this to make diagnosis easier. A physical exam will be done and during this exam the doctor will be looking for specific issues, including:

    • Overexaggerated reflexes
    • Spasticity

    Blood and urine tests are also often performed. These tests will be able to show if the patient's uric acid levels are high. Decreased HGP enzyme levels can be looked for using a skin biopsy.

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    How is Lesch-Nyhan Syndrome Treated?

    There is no specific treatment method that can treat this disorder. Lesch-Nyhan syndrome is also incurable. The neurological symptoms cannot be improved by decreasing the uric acid levels, but decreasing these levels has other benefits and can be done by having the patient take allopurinol, a gout medication.

    Some of the other symptoms may be alleviated with certain medications, as well. These medications include:

    • Carbidopa
    • Levodopa
    • Phenobarbital
    • Diazepam
    • Haloperidol

    The prognosis for Lesch-Nyhan syndrome is poor in most cases. Patients will typically need a wheelchair to get around, as well as assistance with sitting down and standing up, and walking.

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    Medline Plus. (2008). Lesch-Nyhan Syndrome. Retrieved on June 29, 2010 from Medline Plus:

    Genetics Home Reference. (2007). Lesch-Nyhan Syndrome. Retrieved on June 29, 2010 from Genetics Home Reference:

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