[Complete and partial deficiency of HPRT]

The Lesch-Nyhan syndrome results from a complete or virtually complete deficiency of the purine salvage enzyme, hypoxanthine guanine phosphoribosyl transferase (HPRT). The disease is characterized by hyperuricemia, choreoathetosis, spasticity, compulsive self-mutilation, and mental retardation. Patients with a partial deficiency of HPRT are spared most of the neurological disorder of Lesch-Nyhan syndrome. The specific relationship between HPRT deficiency and the neurological dysfunction in the Lesch-Nyhan syndrome is not known, at present. The genetic lesion which result in HPRT deficiency are heterogeneous. About 90 different mutations were found in over 110 families. The DNA-based mutation detection technique can be used for the diagnosis of affected males and for the determination of carrier status of asymptomatic females. This technique is also applicable for the prenatal diagnosis for Lesch-Nyhan syndrome. Transgenic mice, deficient in HPRT activity, have been obtained but they do not show any neurological dysfunction. After administration of 9-ethyladenine, however, they showed the self-injury behavior.