Cramer S D, Ferree P M, Lin K, Milliner D S, Holmes R P
Department of Cancer Biology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
Hum Mol Genet. 1999 Oct;8(11):2063-9. doi: 10.1093/hmg/8.11.2063.
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.
II型原发性高草酸尿症（PH2）是一种罕见的单基因疾病，其特征是缺乏催化羟基丙酮酸还原为D -甘油酸、乙醛酸还原为乙醇酸以及D -甘油酸氧化为羟基丙酮酸的酶。该疾病的特点是尿中草酸盐和L -甘油酸排泄增加。草酸盐排泄增加可导致肾结石和肾钙质沉着，在某些情况下可导致肾衰竭和全身性草酸盐沉积。我们从人肝脏表达序列标签（EST）文库中鉴定出一个乙醛酸还原酶/羟基丙酮酸还原酶（GRHPR）cDNA克隆。核苷酸序列分析确定了一个1198个核苷酸的克隆，其编码一个984个核苷酸的开放阅读框。该开放阅读框编码一个预测的328个氨基酸的蛋白质，质量为35563道尔顿。将该cDNA克隆瞬时转染到COS细胞中，证实其编码一种具有羟基丙酮酸还原酶、乙醛酸还原酶和D -甘油酸脱氢酶活性的酶。对人类ESTs的数据库分析显示其在广泛的组织中表达，表明该酶可能在代谢中具有以前未被认识的作用。确定了人类GRHPR基因的基因组结构，其包含9个外显子和8个内含子，跨越9号染色体着丝粒周围约9kb。通过单链构象多态性分析，对来自两个无关家庭的两对同胞的4例PH2患者进行了GRHPR突变分析。所有4例患者在第2外显子的第35密码子处均为单核苷酸缺失的纯合子，导致第45密码子处出现提前终止密码子。我们鉴定出的cDNA代表了动物GRHPR序列的首次特征描述。我们提供的数据将有助于未来的基因检测以确诊PH2的临床诊断。这些数据也将有助于对受PH2影响家庭中的杂合子检测和产前检测，以辅助遗传咨询。
