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
