A deficiency in just one bodily enzyme, hypoxanthine-guanine phosphoribosyltransferase (HPRT), profoundly inhibits the body's ability to process uric acid, which leads to a variety of problems, some understandable, some tragically unfathomable. Lesch-Nyhan Syndrome refers to this genetically inherited disease and all its resulting side effects. The first symptoms show up in infancy, with "orange sand", urate crystal formations, visible during diaper changes.
Over the years, elevated uric acid levels gradually poison all manner of body parts, resulting in chronic itching and pain, renal difficulty, and even neurological damage. As terrible as gout, another uric acid-related disease, is thought to be, LNS is much worse, if only for the way it compels sufferers to engage in self-mutilation. The arms, fingers, nose, lips, and eyes are often irresistably itchy, leaving the sufferer to scratch or bite at these parts until he or she is physically prevented from continuing. Biting off fingers or chunks of the lip is not uncommon, even though the sufferer feels all the pain during these episodes.
While the drug allopurinol may help rid the body of excess uric acid, it will not reverse any damage that has already occurred. Even with a battery of medications for pain, renal function, and inevitable neurological damage, LNS sufferers generally face a poor prognosis.
Sources: National Institute of Neurological Disorders and Stroke and online notes from Cliff Davis, DDS