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Lesch-Nyhan disease (LND) was first described as a specific clinical condition in 1964 (Lesch & Nyhan, 1964). It is a rare X-linked recessive disorder involving a virtual complete absence of activity of the enzyme hypoxanthine-phosphoribosyltransferase (HPRT). The lack of HPRT activity results in an extreme overproduction of uric acid and related symptoms of gout and renal dysfunction. In addition, all patients have neurological abnormalities including spasticity, choreoasthetosis, dysarthria, and a unique compulsion to self-injure, abuse others (physically and verbally) and to lie and curse. The extrapyramidal symptoms are so severe that patients are unable to sit or stand without assistance. The muscles controlling vocal production are similarly affected and their speech can be understood only with great difficulty. Self-injury starts as young as 2 years of age with lip and finger biting being the most typical. As they grow older, patients injure themselves in any way they can devise.
Lesch-Nyhan Disease is most commonly inherited but it can also occur via a spontaneous genetic mutation. About 1/3 of the cases result from a spontaneous mutation. Because this is a recessive, X linked genetic disease, males have the disease and females are carriers. If a mother is a carrier, there is a 50/50 chance that her male offspring will have the disease and 50/50 chance that her daughters will be carriers. (There are two documented cases of females having the disease. These cases were not inherited but must have occurred through a exceedingly rare mutation.) LND appears to be distributed evenly among races and geographic locations. It has been hypothesized to occur as frequently as one in every 380,000 births (Crawhall, 1972). However, tabulations of the actual number of cases suggest that it is even more rare. The Norwegian Ministry of Health reports only 3 cases in a country with a population of just under 4½ million. Only 7 cases have been discovered in New York City which has a population of a little over 8 million.