Lesch-Nyhan Disease

Lesch-Nyhan disease is caused by a congenital enzyme deficiency in the body

Pathophysiology

1) inborn error of purine metabolism 2) marked by complete deficiency in hypoxanthine phosphoribosyltransferase (HPRT)

Signs and Symptoms

1) severe mental retardation 2) self-mutilation 3) spasticity 4) choreoathetosis 5) gout 6) uric acid kidney stones

Characteristic Test Findings

Laboratory – increase serum uric acid levels

Biochemistry

HPRT is a catalyst for combining guanine and hypoxanthine and also guanine and phosphoribosyl pyrophospate to make IMP and GMP, respectively

Inheritance/Epidemiology

X-linked inheritance

Treatment

1) indomethacin, allopurinol, and colchines for the gout, kidney stones, and urate overproduction 2) strategies for controlling self-mutilation – removal of teeth, mouth guards, and the use of pharmaceutical agents gabapentin, risperidone, and carbamazepine 3) there is unfortunately no treatment for the mental retardation and CNS sequelae

Tips for USMLE

if the question mentions self-mutilation (chewing off fingers), mental retardation, and gout in a 5 year-old boy, think Lesch-Nyhan