Question:easy
Lesch-Nyhan syndrome is caused by deficiency of which enzyme?
Lesch-Nyhan syndrome is caused by deficiency of which enzyme?
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Self-mutilation plus hyperuricemia points to a defect in the purine salvage enzyme.
Updated On: Jun 23, 2026
- Orotate phosphoribosyltransferase
- Uracil phosphoribosyltransferase
- Quinolinate phosphoribosyltransferase
- Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)
Show Solution
The Correct Option is D
Solution and Explanation
Step 1: Recall the two ways cells obtain purine nucleotides: a costly de-novo route and an economical salvage route. Salvage of the purine bases hypoxanthine and guanine is done by one enzyme - HGPRT.
Step 2: Total loss of HGPRT removes the salvage option entirely, so the substrate PRPP that salvage would have used is spared and instead pushes the de-novo machinery into overdrive.
Step 3: The net result is excess purine turnover and a flood of uric acid, explaining the gout, renal stones, and hyperuricemia, while CNS involvement adds intellectual disability and compulsive self-injury.
Step 4: The distractors act on pyrimidine (orotate, uracil) or NAD precursor (quinolinate) handling, none of which links to this salvage-defect syndrome. \[\boxed{\text{HGPRT}}\]
Step 2: Total loss of HGPRT removes the salvage option entirely, so the substrate PRPP that salvage would have used is spared and instead pushes the de-novo machinery into overdrive.
Step 3: The net result is excess purine turnover and a flood of uric acid, explaining the gout, renal stones, and hyperuricemia, while CNS involvement adds intellectual disability and compulsive self-injury.
Step 4: The distractors act on pyrimidine (orotate, uracil) or NAD precursor (quinolinate) handling, none of which links to this salvage-defect syndrome. \[\boxed{\text{HGPRT}}\]
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