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.L^4-8 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.