title: The gene encoding hydroxypyruvate reductase (GRHPR) is mutated in patients with primary hyperoxaluria type II.
abstract: Primary hyperoxaluria type II (PH2) is a rare monogenic disorder that is characterized by a lack of the enzyme that catalyzes the reduction of hydroxypyruvate to D-glycerate, the reduction of glyoxylate to glycolate and the oxidation of D-glycerate to hydroxypyruvate. The disease is characterized by an elevated urinary excretion of oxalate and L-glycerate. The increased oxalate excretion can cause nephrolithiasis and nephrocalci-nosis and can, in some cases, result in renal failure and systemic oxalate deposition. We identified a glyoxylate reductase/hydroxypyruvate reductase (GRHPR) cDNA clone from a human liver expressed sequence tag (EST) library. Nucleotide sequence analysis identified a 1198 nucleotide clone that encoded a 984 nucleotide open reading frame. The open reading frame encodes a predicted 328 amino acid protein with a mass of 35 563 Da. Transient transfection of the cDNA clone into COS cells verified that it encoded an enzyme with hydroxy-pyruvate reductase, glyoxylate reductase and D-glycerate dehydrogenase enzymatic activities. Database analysis of human ESTs reveals widespread tissue expression, indicating that the enzyme may have a previously unrecognized role in metabolism. The genomic structure of the human GRHPR gene was determined and contains nine exons and eight introns and spans approximately 9 kb pericentromeric on chromosome 9. Four PH2 patients representing two pairs of siblings from two unrelated families were analyzed for mutations in GRHPR by single strand conformation polymorphism analysis. All four patients were homozygous for a single nucleotide deletion at codon 35 in exon 2, resulting in a premature stop codon at codon 45. The cDNA that we have identified represents the first characterization of an animal GRHPR sequence. The data we present will facilitate future genetic testing to confirm the clinical diagnosis of PH2. These data will also facilitate heterozygote testing and prenatal testing in families affected with PH2 to aid in genetic counseling.
authors.affiliation: Department of Cancer Biology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA. scramer@wfubmc.edu
authors.forename: S D
authors.initials: SD
authors.lastname: Cramer
authors.forename: P M
authors.initials: PM
authors.lastname: Ferree
authors.forename: K
authors.initials: K
authors.lastname: Lin
authors.forename: D S
authors.initials: DS
authors.lastname: Milliner
authors.forename: R P
authors.initials: RP
authors.lastname: Holmes
mesh_terms: D000429:Alcohol Oxidoreductases / Q000172:deficiency / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D003062:Codon / Q000235:genetics; D016384:Consensus Sequence; D018076:DNA, Complementary / Q000235:genetics; D005091:Exons / Q000235:genetics; D020224:Expressed Sequence Tags; D005796:Genes; D006801:Humans; D050537:Hydroxypyruvate Reductase; D006959:Hyperoxaluria / Q000145:classification / Q000201:enzymology / Q000235:genetics*; D008099:Liver / Q000737:chemistry; D008969:Molecular Sequence Data; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014162:Transfection
chemical_list: D003062:Codon; D018076:DNA, Complementary; D000429:Alcohol Oxidoreductases; D050537:Hydroxypyruvate Reductase