Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.6.1.44 (AGT)
 770 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Primary hyperoxaluria (PH) is an autosomal-recessive disorder of endogenous oxalate synthesis characterized by accumulation of calcium oxalate primarily in the kidney. Deficiencies of alanine-glyoxylate aminotransferase (AGT) or glyoxylate reductase (GRHPR) are the two known causes of the disease (PH I and II, respectively). To determine the etiology of an as yet uncharacterized type of PH, we selected a cohort of 15 non-PH I/PH II patients from eight unrelated families with calcium oxalate nephrolithiasis for high-density SNP microarray analysis. We determined that mutations in an uncharacterized gene, DHDPSL, on chromosome 10 cause a third type of PH (PH III). To overcome the difficulties in data analysis attributed to a state of compound heterozygosity, we developed a strategy of "heterozygosity mapping"-a search for long heterozygous patterns unique to all patients in a given family and overlapping between families, followed by reconstruction of haplotypes. This approach enabled us to determine an allelic fragment shared by all patients of Ashkenazi Jewish descent and bearing a 3 bp deletion in DHDPSL. Overall, six mutations were detected: four missense mutations, one in-frame deletion, and one splice-site mutation. Our assumption is that DHDPSL is the gene encoding 4-hydroxy-2-oxoglutarate aldolase, catalyzing the final step in the metabolic pathway of hydroxyproline.
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PMID:Mutations in DHDPSL are responsible for primary hyperoxaluria type III. 2211 83

Urinary excretion of oxalate is one of risk factors in urinary stone formation. Prevention of undesirable overflow into the production of oxalate definitely leads to a decrease of urolithiasis. The activity of serine : pyruvate/alanine : glyoxylate aminotransferase (SPT/AGT) or glyoxylate reductase/hydroxypyruvate reductase (GRHPR), the key enzyme of primary hyperoxlauria type 1 and 2, respectively, and their subcellular distribution highly affects the oxalate production. On the other hand, urolithiasis is tightly related to lifestyle disease, such as diabetes mellitus and insulin resistance. The hypothesis that insulin resistance induces mitochondria dysfunction, resulting in the decrease of mitochondria-related enzyme activity is a very attractive new treatment strategy of urolithiasis. Namely, the improvement of insulin resistance might prevent stone formation.
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PMID:[Future perspective in the treatment of urolithiasis based on oxalate metabolism]. 2130 60

Primary hyperoxaluria type 1 (PH1) and type 2 (PH2) are rare genetic diseases that result from deficiencies in glyoxylate metabolism. The increased oxalate synthesis that occurs can lead to kidney stone formation, deposition of calcium oxalate in the kidney and other tissues, and renal failure. Hydroxyproline (Hyp) catabolism, which occurs mainly in the liver and kidney, is a prominent source of glyoxylate and could account for a significant portion of the oxalate produced in PH. To determine the sensitivity of mouse models of PH1 and PH2 to Hyp-derived oxalate, animals were fed diets containing 1% Hyp. Urinary excretions of glycolate and oxalate were used to monitor Hyp catabolism and the kidneys were examined to assess pathological changes. Both strains of knockout (KO) mice excreted more oxalate than wild-type (WT) animals with Hyp feeding. After 4 wk of Hyp feeding, all mice deficient in glyoxylate reductase/hydroxypyruvate reductase (GRHPR KO) developed severe nephrocalcinosis in contrast to animals deficient in alanine-glyoxylate aminotransferase (AGXT KO) where nephrocalcinosis was milder and with a lower frequency. Plasma cystatin C measurements over 4-wk Hyp feeding indicated no significant loss of renal function in WT and AGXT KO animals, and significant and severe loss of renal function in GRHPR KO animals after 2 and 4 wk, respectively. These data suggest that GRHPR activity may be vital in the kidney for limiting the conversion of Hyp-derived glyoxylate to oxalate. As Hyp catabolism may make a major contribution to the oxalate produced in PH patients, Hyp feeding in these mouse models should be useful in understanding the mechanisms associated with calcium oxalate deposition in the kidney.
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PMID:Hydroxyproline metabolism in mouse models of primary hyperoxaluria. 2249 66

Primary hyperoxaluria (PH) is a rare autosomal recessive disorder of glyoxylate metabolism in humans. It is characterized by the accumulation of oxalate and subsequent precipitation of calcium oxalate crystals, primarily in the kidneys. Deficiencies in glyoxylate-metabolizing enzymes alanine-glyoxylate aminotransferase (AGXT) or glyoxylate reductase/hydroxypyruvate reductase (GRHPR) occur in 95% of PH cases. Seven Coton de Tulear puppies from four apparently unrelated litters were examined owing to sudden illness at the age of 3-4 weeks. A complete necropsy was performed. The typical finding was tubular necrosis with extensive oxalate crystal deposition. Based on history and necropsy findings, PH was suspected. Eight microsatellite loci flanking AGXT and GRHPR were analysed, and based on segregation results, AGXT was suspected as to be the candidate gene. AGXT exon sequencing revealed a single base change (c.996G>A) that changed one conserved residue (p.Gly102Ser). The mutation was tested in of 118 Finnish Coton de Tulear dogs, ten (8.5%) of which were revealed as carriers. This preliminary study reports PH as a cause of neonatal death in Finnish Coton de Tulear and suggests that genetic testing of dogs be carried out before breeding to prevent the birth of affected offspring.
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PMID:Primary hyperoxaluria in Coton de Tulear. 2248 13

Combined liver/kidney transplant is the preferred transplant option for most patients with primary hyperoxaluria type 1 (PH1) since orthotopic liver transplantation replaces the deficient liver-specific AGT enzyme, thus restoring normal metabolic oxalate production. However, primary hyperoxaluria type 2 (PH2) is caused by deficient glyoxylate reductase/hydroxypyruvate reductase (GRHPR), and this enzyme is widely distributed throughout the body. Though the relative abundance and activity of GRHPR in various tissues is not clear, some evidence suggests that the majority of enzyme activity may indeed reside within the liver. Thus the effectiveness of liver transplantation in correcting this metabolic disorder has not been demonstrated. Here we report a case of 44-year-old man with PH2, frequent stone events, and end-stage renal disease; he received a combined liver/kidney transplant. Although requiring confirmation in additional cases, the normalization of plasma oxalate, urine oxalate, and urine glycerate levels observed in this patient within a month of the transplant that remain reduced at the most recent follow-up at 13 months suggests that correction of the GRHPR deficiency in PH2 can be achieved by liver transplantation.
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PMID:Combined Liver-Kidney Transplantation for Primary Hyperoxaluria Type 2: A Case Report. 2916 Sep 59