Gout
Definition: A metabolic disorder caused by increased uric acid levels (hyperuricemia, serum uric acid > 7 mg/dL in men, > 6 mg/dL in women).
Cause: Deposition of monosodium urate crystals in joints due to overproduction or decreased excretion of uric acid (purine metabolism end-product).
Key Enzyme Defect: HGPRT deficiency (as in Lesch–Nyhan syndrome) or increased PRPP synthetase activity.
Clinical Feature: Recurrent attacks of acute monoarticular arthritis — classically at the 1st metatarsophalangeal joint (“podagra”).