Lesch-Nyhan syndrome
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A boy with developmental delay and choreoathetosis exhibits self-injurious behavior including lip and finger biting. Uric acid is elevated and he has gout and kidney stones.
XLR; HPRT1 (hypoxanthine-guanine phosphoribosyltransferase)
- HGPRT deficiency
- Self-injurious behavior (compulsive, recognized as unwanted)
- Choreoathetosis, dystonia
- Hyperuricemia → gout, nephrolithiasis
- Intellectual disability
- Marked hyperuricemia and elevated urine hypoxanthine/uric acid-to-creatinine ratio
- Reduced or absent HGPRT enzyme activity (erythrocyte assay or cultured fibroblasts)
- Confirmation: HPRT1 molecular testing
- Allopurinol (for uric acid), behavioral management
HGPRT = Hyperuricemia, Gout, Pissed off (aggression, self-mutilation), Reduced cognition (intellectual disability), dysTonia (+ spasticity, hyperreflexia).
"He's Got Purine Recovery Trouble": HGPRT (hypoxanthine-guanine phosphoribosyltransferase) is the purine salvage enzyme.
"Leaky HuGgies & PampeRs": orange sodium urate crystals ("sand") in diapers in Lesch-Nyhan. Part of the HALO-M group of X-linked disorders: Hunter, Adrenoleukodystrophy, Lesch-Nyhan, OTC deficiency, Menkes.