A complete deficiency of hypoxanthine guanine phosphoribosyltransferase results in which disease?

• A. Lesch-Nyhan syndrome
• B. Modification of Diet in Renal Disease
• C. Maple syrup urine disease
• D. Reye's syndrome

Answer: (A)

A complete deficiency of HGPRT blocks the purine salvage pathway. HGPRT normally recycles hypoxanthine to IMP and guanine to GMP, using PRPP. Without this enzyme, purines aren’t salvaged and are instead degraded to uric acid, which drives hyperuricemia. This metabolic disturbance underlies Lesch-Nyhan syndrome, an X-linked disorder characterized by very high uric acid levels and notable neurological and behavioral abnormalities, including self-injury and motor dysfunction. The other options do not involve HGPRT or purine salvage: one is a renal-diet study, another is a metabolic disorder affecting branched-chain amino acids, and the last is an aspirin-associated encephalopathy with liver failure.