HPRT - (Hypoxanthine phosphoribosyltransferase)

HPRT deficiency either partial or complete, results in hyperuricaemia due to uric acid overproduction. It is an X-linked disorder. Complete HPRT deficiency results in Lesch-Nyhan Disease (LND), characterised by hyperuricaemia, choreoathetosis, spasticity, and difficulties with speech and feeding. The hallmark of the condition is compulsive self-mutilation and aggression. There is a phenotypic spectrum with residual enzyme activity protecting against some or all neurological abnormalities including self-injurious behaviour. Patients with partial HPRT deficiency may present with gout as teenagers. Biochemical markers for HPRT are purine over production seen as an increased uric acid/creatinine ratio in urine, a raised plasma uric acid, and raised NAD levels in the red cell nucleotide profile.