Identification of Two Independent Japanese Mutant HPRT Genes Using the PCR Technique

Abstract

Deficiency of a purine salvage enzyme, hypoxanthine guanine phosphoribosyltransferase (HPRT), is resulted in two distinct clinical disorders, which are inherited as an X linked recessive trait. Complete deficiency of HPRT leads to Lesch-Nyhan syndrome,1 whereas partial deficiency causes severe form of gout.2 The gene for HPRT located on the long arm of X chromosome consists of nine exons and eight introns, and recently, the sequence of 57 kb of the entire human HPRT gene locus was determined.3 The molecular analysis of mutations at the human HPRT locus has been greatly facilitated by the recent development of polymerase chain reaction (PCR), coupled with direct-sequencing. The technique of PCR amplification of reverse-transcribed mRNA has recently been used to identify the molecular basis of HPRT deficiency in number of subjects.L4-8 Further, the elucidation of the complete DNA sequence of the human HPRT gene locus3 has been enabled the analysis by the amplification of all nine HPRT exons from genomic DNA.9 In this studies, we report two independent mutant HPRT genes from a patient of HPRT partial deficiency associated with gout and from a patient of Lesch-Nyhan syndrome, identified by the analyses of PCR amplified product of cDNA synthesized from mRNA and also the product of each exon from genomic DNA.