Molecular analysis of the mutations in five unrelated patients with the Lesch Nyhan syndrome.

We have identified the mutations in the hypoxanthine phosphoribosyltransferase (hprt) gene in five patients with the Lesch Nyhan syndrome (LN) by direct sequencing of hprt cDNA and genomic DNA. Three of the mutations affect splicing of exons 1, 2, and 9, respectively, while two are missense mutations in exons 3 and 8. All 5 mutations result in profound hprt deficiency as measured in fibroblast lysates. However, small differences in the clinical phenotype are seen between the patients. All these mutations are unique and have not been reported previously.