Lesch-Nyhan syndrome

Injury	Disease	Nutrition	Poison

Symptoms	Surgery	Test	Special Topic

Lesch-Nyhan syndrome

Definition:

Lesch-Nyhan syndrome is an inheritable disorder that affects purine metabolism. It affects how the body handles the building and breakdown of purines -- one of the chemical units that make up RNA and DNA molecules.

Causes, incidence, and risk factors:

Lesch-Nyhan syndrome is inherited as an X-linked trait, therefore the disease is seen only in males. It is characterized by increased blood and uric acid levels and by the absence of the enzyme hypoxanthine guanine phosphoribosyltransferase (HGP).

Males with Lesch-Nyhan have delayed motor development followed by bizarre, sinuous movements and increased deep tendon reflexes. A striking feature of Lesch-Nyhan syndrome is self-destructive behavior characterized by chewing off fingertips and lips, if not restrained.

The excess uric acid levels cause children to develop gout-like swelling in some of their joints. In some cases, renal dysfunction develops because of the excess uric acid levels.

Symptoms:

family history of Lesch-Nyhan syndrome
male infant with delayed motor development
movement disorder
destructive chewing of fingers or lips (self-destructive behavior)

Signs and tests:

Physical examination and testing may show:

hyperreflexia
spasticity
choreoathetoid movements
compulsive self-destructive behavior
increased serum uric acid
increase excretion of uric acid, urine
decreased HGP levels in cultured fibroblasts

Tests:

serum chemistry, uric acid
urine chemistry, uric acid
skin biopsy tissue culture (fibroblasts)

Treatment:

No specific treatment exists for Lesch-Nyhan syndrome. Allopurinol has been tried, and although it decreases the uric acid concentrations, it does not improve the neurological outcome.

Some symptoms may be relieved with the drugs carbidopa/levodopa, diazepam, phenobarbital, or haloperidol.

Recent advances in recombinant DNA techniques have allowed the gene responsible for the production of HGP to be cloned. Attempts will be made in the future to insert this gene into a patient's genetic material to determine if it will correct the metabolic defect.

Expectations (prognosis):

The outcome is likely to be poor, even with attempts to treat the condition.

Complications:

Severe, progressive disability is likely.

Calling your health care provider:

Call your health care provider if signs of this illness appear in your child or if there is a history of Lesch-Nyhan syndrome in your family.

Prevention:

Genetic counseling for prospective parents with a family history of Lesch-Nyhan syndrome is recommended. The carrier state of the mother may be determined by culture of skin fibroblasts. Half the fibroblasts will have normal levels of the HGP enzyme and the remaining half will have deficient or absent HGP.

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