Lesch-Nyhan Syndrome

(Hypoxanthine-Guanine Phosphoribosyltransferase Deficiency or HPRT Deficiency; Lesch-Nyhan Disease)

by Michelle Badash, MS

Definition

Lesch-Nyhan syndrome is a genetic disorder. It affects 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, neurologic disability, and behavioral problems, including self-injury. It is a rare condition.

Causes

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 the person's mother, who is a carrier.

Risk Factors

Lesch-Nyhan syndrome is more common in men. Having male family members with Lesch-Nyhan syndrome (on the mother's side) also increases the risk.

Symptoms

The first symptom of Lesch-Nyhan syndrome may be orange-colored crystal-like deposits in the diaper. This may occur in children as young as 3 months. These deposits are caused by increased uric acid in the urine. Other symptoms include:

Irritability
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
Delayed development
Behavioral problems occur in all cases and self injury in about 85%
Pain and swelling of joints
Difficulty swallowing and vomiting
Muscle spasm
Blood in the urine from kidney stones

Uric Acid Deposits in a Joint

Self-Injury

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 2 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.

Diagnosis

You will be asked about your child's symptoms, behavior traits, and medical history. A physical exam will be done.

Your child's bodily fluids may be tested. This can be done with blood tests. Reduced levels of the HPRT enzyme will confirm the diagnosis.

Treatment

There is no treatment to cure Lesch-Nyhan. However, good hydration and certain medications may help to alleviate some of its symptoms. These may include:

Medications

The following medications may be used:

Allopurinol—to control excessive levels of uric acid in the body
Antipsychotics
Anticonvulsants
Medications to reduce muscle spasms

Behavioral problems may also be managed with a combination of behavioral modification techniques and medication.

S-adenosylmethionine—2 reports 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 a doctor 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 people live longer with good medical and psychological care.

Prevention

There are no guidelines to prevent Lesch-Nyhan syndrome. If you have a family history of this condition, you can talk to a genetic counselor when deciding whether to have children.

RESOURCES:

National Institute of Neurological Disorders and Stroke
http://www.ninds.nih.gov

National Organization of Rare Disorders
http://www.rarediseases.org

CANADIAN RESOURCES:

About Kids Health—The Hospital for Sick Children
http://www.aboutkidshealth.ca

CORD—Canadian Organization for Rare Disorders
http://www.cord.ca

References:

Dolcetta D, et al. Quantitative evaluation of the clinical effects of S-Adenosylmethionine on mood and behavior in Lesch-Nyhan patients. Nucleosides Nucleotides Nucleic Acids. 2013;32:174–88.

Glick N. Dramatic reduction in self-injury in Lesch-Nyhan disease following S-adenosylmethionine administration. J Inherit Metab Dis. 2006;29(5):687.

Lesch-Nyhan syndrome. GeneReviews website. Available at:
...(Click grey area to select URL)
Updated May 15, 2014. Accessed August 23, 2017.

Lesch-Nyhan syndrome. National Organization for Rare Disorders website. Available at: https://rarediseases.org/rare-diseases/lesch-nyhan-syndrome/. Published 2015. Accessed August 23, 2017.

Lesch-Nyhan syndrome. Online Mendelian Inheritance in Man (OMIM) website. Available at: https://www.omim.org/entry/300322. Updated July 9, 2017. Accessed August 23, 2017.

Last reviewed September 2018 by EBSCO Medical Review Board Michael Woods, MD, FAAP
Last Updated: 8/6/2015