(Hypoxanthine-Guanine Phosphoribosyltransferase Deficiency or HPRT Deficiency; Lesch-Nyhan Disease)
Lesch-Nyhan syndrome is a genetic disorder. It effects the metabolism of purines in the body. Purines are protein molecules that are important for the metabolism of RNA and DNA, which make up our genetic codes. Lesch-Nyhan syndrome is characterized by uric acid build-up and self-injury. This disease, which mainly affects men, is rare, occurring 1 of every 100,000 males.
Lesch-Nyhan syndrome is caused by a mutation or change in a gene. This change results in the absence of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT). HPRT is needed to metabolize uric acid. Without this enzyme, uric acid builds up in the central nervous system, kidneys, and other areas of the body.
This gene mutation occurs on the X chromosome. It can either be a new mutation in the affected person or inherited from his mother, who is a carrier.
A risk factor is something that increases your chance of getting a disease or condition. Risk factors for developing Lesch-Nyhan syndrome include:
- Sex: male
- Having male family members on the mother's side of the family with Lesch-Nyhan syndrome
The first symptom of Lesch-Nyhan syndrome is orange-colored crystal-like deposits in the diaper. This may occur in children as young as three months. These deposits are caused by increased uric acid in the urine. Other symptoms include:
Nervous system impairment:
- 4 to 6 months—lack of muscle tone and inability to lift the head
- 6 months—unusual arching of the back
- 9 months—inability to crawl or stand
- 12 months—inability to walk
- 12+ months—spasms of the limbs and facial muscles
- Kidney stones]]>
- Blood in the urine
- Pain and swelling of joints
- Difficulty swallowing ( ]]>dysphagia]]> )
- Impaired kidney function
Uric Acid Deposits in Joint
]]>Self-mutilating]]> behavior is the hallmark of this disease. Children begin to bite their fingers, lips, and the insides of their mouths as early as two years old.
As children grow, self-injury becomes increasingly compulsive and severe. Eventually, mechanical physical restraints will be necessary to prevent head and leg banging, nose gouging, loss of fingers and lips from biting, and loss of vision from eye rubbing, among others. In addition to self-injury, older children and teens will become physically and verbally aggressive.
The cause of these behaviors is not entirely understood. However, some experts believe it is related to abnormalities in brain chemicals called neurotransmitters. It should be stressed that the child does not want to hurt himself or others, but is incapable of preventing these behaviors. People with Lesch-Nyhan syndrome have been described as “doing the opposite” of what they really want.
The doctor will ask about symptoms, behavior traits, and medical history, and perform a physical exam. Tests may include:
- Measurement of HPRT enzyme activity—to confirm the diagnosis
- Molecular genetic testing of the HPRT1 gene—to confirm the diagnosis and to detect if an unaffected female is a carrier of the gene mutation
There is no treatment to cure Lesch-Nyhan. However, certain medications may help to alleviate some of its symptoms. For example:
To control excessive levels of uric acid in the body:
- Allopurinol (Aloprim, Zyloprim)
To help reduce some of the problem behaviors:
- Diazepam (Diastat, Valium)
- Haloperidol (Haldol)
- Phenobarbital (Luminal)
- S-adenosylmethionine—A single 2006 report suggests that administration of s-adenosylmethionine, a food supplement, may reduce self-mutilating behaviors in adults with this syndrome. This supplement, which is available in health food stores, is naturally synthesized by the human body and important for many bodily processes. Talk to your healthcare provider before taking any supplements.
With treatment, the average life expectancy is early- to mid-20s. There may be an increased risk of sudden death due to respiratory causes. However, many patients live longer with good medical and psychological care.
National Organization of Rare Disorders
National Institute of Neurological Disorders and Stroke
Canadian Organization for Rare Disorders
Glick N. Dramatic reduction in self-injury in Lesch-Nyhan disease following S-adenosylmethionine administration. J Inherit Metab Dis. 2006;29:687.
Lesch-Nyhan Disease National Registry. New York University School of Medicine, Department of Psychiatry.
National Institute of Neurological Disorders and Stroke website. Available at: http://www.ninds.nih.gov .
The National Library of Medicine website. Available at: http://www.nlm.nih.gov .
New York University School of Medicine website. Available at: http://www.med.nyu.edu/ .
Neychev VK, Jinnah H. Sudden death in Lesch-Nyhan disease. Dev Med Child Neurol. 2006;48:923-926.
The Purine Research Society website. Available at: http://www.purineresearchsociety.org/ .
University of Washington and Children's Health System Seattle. Lesch-Nyhan syndrome. GeneTests, GeneClinics: Medical Genetics Information Resource (database online). 1993-2002. Gene Tests website. Available at: http://www.genetests.org. Accessed June 2002.
Last reviewed November 2008 by ]]>Rosalyn Carson-DeWitt, MD]]>
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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