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 type 1 (PH1) is caused by deficiency of peroxisomal alanine-glyoxylate aminotransferase which is in humans exclusively expressed in liver cells. The disease is inherited as an autosomal recessive trait, and initial symptoms usually occur in early childhood. Up to the age of 25 years, 90% of the patients are symptomatic, and many patients develop end-stage renal failure. Pronounced medical care is necessary in PH1 patients to prevent generalized oxalosis with complications due to bone disease and peripheral gangrene. The rather short survival of patients on hemodialysis is caused by sudden arrhythmias and heart block. As no dialysis procedure is able to remove the daily produced oxalate, early transplantation is mandatory. Our 45-year-old patient is remarkable on the basis of the late manifestations of PH1. The diagnosis was delayed by unspecific symptoms of nephrolithiasis with recurrent pyelonephritis. Clinical course and diagnostic cornerstones of primary hyperoxaluria are outlined. The principles of conservative treatment and experiences with dialysis and transplantation are discussed.
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PMID:Primary hyperoxaluria type 1 causing end-stage renal disease in a 45-year-old patient. 1117 30

Mutations in the CLCN5 gene have been detected in Dent's disease and its phenotypic variants (X-linked recessive nephrolithiasis, X-linked recessive hypophosphatemic rickets, and idiopathic low-molecular-weight proteinuria of Japanese children). Dent's disease is a tubular disorder characterized by low-molecular-weight proteinuria, and nephrolithiasis associated with nephrocalcinosis and hypercalciuria. ClC-5 is the first chloride channel for which a definitive role in the trafficking and acidification-dependent recycling of apical membrane proteins has been established. In the course of CLCN5 SSCP analysis in patients with hypercalciuric nephrolithiasis, we detected a novel mutation at intron 2 of the CLCN5 gene, a T-to-G substitution, located 17 bp upstream of the AG acceptor site. To determine the effect of IVS2-17 T>G mutation on the correct splicing of intron 2, we studied ClC-5 transcripts in a patient's peripheral blood leukocytes by means of quantitative comparative RT/PCR, and found a new ClC-5 5' UTR isoform characterized by the untranslated exon 1b and by retention of intron 1b. This new isoform--isoform B1--was not correlated with mutation since it was detected also in control leukocytes and in renal tissues of kidney donors, thus confirming its physiological role. By RACE analysis we determined the putative transcriptional start site which is located at intron 1a, 251 nt upstream of the first nucleotide of the untranslated exon 1b. ORF analysis revealed that intron 1b retention in isoform B1 stabilizes the initiation of translation to the AGT at position 297 of the ClC-5 cDNA coding region.
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PMID:Identification of a novel splice site mutation of CLCN5 gene and characterization of a new alternative 5' UTR end of ClC-5 mRNA in human renal tissue and leukocytes. 1467 7

We report herein a domino orthotopic liver transplantation (LT), from a 38-year-old woman undergoing liver-kidney transplantation (LKT) for primary hyperoxaluria type I (PH1) to a recipient with cirrhosis and hepatocellular carcinoma. Delayed onset of PH1 and renal failure and 10% residual alanine-glyoxylate aminotransferase (AGT) activity in domino liver justified its use for domino procedure. The clinical course after LKT was similar to that described in other series, including ours. Renal function started promptly and maintained despite sustained hyperoxaluria from dissolution of oxalotic deposits. Conversely, the domino recipient manifested severe hyperoxaluria and developed nephrolithiasis and renal insufficiency with rapid progression over 2 months. A new LT resulted in slow decrease of oxaluria and improvement of renal function. Therefore, PH1 behaved quite differently in these two patients, leading us to conclude that domino LT using livers from PH1 patients should be considered very carefully, only as a bridge to definitive LT in recipients with critical clinical conditions.
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PMID:Severe course of primary hyperoxaluria and renal failure after domino hepatic transplantation. 1609 18

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

Primary hyperoxaluria (PH) is a rare autosomal recessive disease caused by the functional defect of alanine-glyoxylate aminotransferase (AGT) enzyme in the liver and it is characterized by the deposition of diffuse calcium oxalate crystals. A 38-year-old male patient presented with history of recurrent nephrolithiasis and has received chronic hemodialysis treatment for 2 years. Cadaveric renal transplantation was applied to the case. The patient was reoperated on postoperative day 13 because of the collection surrounding the urethra. During this operation, kidney biopsy was made due to late decrease in creatinine levels. Deposition of diffuse oxalate crystal was detected in allograft kidney biopsy, whereas in the 0-hour biopsy there were no oxalate crystals. Oxalate level was found to be high in a 24-hour urine specimen (118 mg/L, normal level: 7-44 mg/L). The patient was identified with primary hyperoxaluria and followed up in terms of systemic oxalate deposition as well as allograft kidney. In the kidney biopsy taken after 18 months, we detected that oxalate crystals almost entirely disappeared. In our case, bilateral preretinal, intraretinal, and intravascular diffuse oxalate crystals were detected, and argon laser photocoagulation treatments were needed for choroidal and retinal neovascularization. Repeated ophthalmic examinations showed the regressive nature of oxalate depositions. In the 18th month, fundus examination and fluorescein angiography revealed that oxalate crystals were significantly regressed. To increase the quality of life and slow down the systemic effects of oxalosis, kidney-only transplantation is beneficial.
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PMID:Regressive course of oxalate deposition in primary hyperoxaluria after kidney transplantation. 2086 24

Primary hyperoxaluria is a genetic disorder in glyoxylate metabolism that leads to systemic overproduction of oxalate. Functional deficiency of alanine-glyoxylate aminotransferase in this disease leads to recurrent nephrolithiasis, nephrocalcinosis, systemic oxalosis, and kidney failure. We present a young woman with end-stage renal disease who received a kidney allograft and experienced early graft failure presumed to be an acute rejection. There was no improvement in kidney function, and she was required hemodialysis. Ultimately, biopsy revealed birefringent calcium oxalate crystals, which raised suspicion of primary hyperoxaluria. Further evaluations including genetic study and metabolic assay confirmed the diagnosis of primary hyperoxaluria type 1. This suggests a screening method for ruling out primary hyperoxaluria in suspected cases, especially before planning for kidney transplantation in patients with end-stage renal disease who have nephrocalcinosis, calcium oxalate calculi, or a family history of primary hyperoxaluria.
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PMID:Recurrence of primary hyperoxaluria after kidney transplantation. 2205 78

Renal stone disease may ensue from either derangements of urine biochemistries or anatomic abnormalities of kidneys and urinary tract. Genetic, environmental and dietary factors may also cooperate in the pathophysiology of nephrolithiasis. An adequate metabolic evaluation should focus on the urinary excretion of promoters and inhibitors of stone formation as well as on the occurrence of systemic diseases potentially related to secondary nephrolithiasis (i.e., endocrine disturbances, malabsorption, bone diseases). Moreover, metabolic investigations should provide reliable information on patient's dietary habits, guide towards the best therapeutic approach and enable the physician to verify patient's compliance to prescribed therapies.AN EXTENSIVE METABOLIC EVALUATION IS RECOMMENDED IN PATIENTS WITH ACTIVE STONE DISEASE (NAMELY, AT LEAST ONE NEW STONE WITHIN THE LAST TWO YEARS), OR IN THOSE HAVING HAD A SINGLE STONE EPISODE OCCURRED IN PECULIAR CONDITIONS: familial history of disease, childhood, menopause, pregnancy, systemic diseases. Simplified protocols may be adequate in non-active nephrolithiasis or in patients with single stone and no relevant risk factors.In our Stone Centre, a so-called "first level screening" is performed by routine, in order to assess urinary supersaturation with stone forming salts and evaluate the excretion of dietary-related metabolites in urine. Relative blood and urine determinations are reported below.IN VENOUS BLOOD: urea, creatinine, uric acid, Na, K, total and ionised Ca, Mg, P, Cl, alkaline phosphatase, gas analysis. In 24-hr urine samples: urea, creatinine, uric acid, Na, K, Ca, Mg, P, Cl, oxalate, inorganic sulphate, citrate, pH, ammonia and titratable acidity. IN FASTING URINE SAMPLES: Ca, citrate, creatinine, hydroxyproline, Brand's test for cistinuria, urine sediment, urine culture. If the first-level evaluation suggested an abnormal bone turnover, then further determinations are warranted, namely, calciotropic hormones (blood Vitamin D and PTH), markers of bone resorption (urine pyridinium crosslinks, serum crosslaps) and formation (serum osteocalcin) bone mineral density.EVENTUALLY, MORE SOPHISTICATED INVESTIGATIONS ARE REQUIRED TO IMPROVE THE DIAGNOSIS OF PECULIAR DISEASES: serum oxalate and glycolate, urine glycolate and L-glycerate, hepatic AGT activity (primary hyperoxalurias); genetic tests (hereditary nephrolithiasis); acidification tests (renal tubular acidosis).
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PMID:Biochemical evaluation in renal stone disease. 2246 Sep 94

Primary hyperoxaluria is a genetic disorder in glyoxylate metabolism that leads to systemic overproduction of oxalate. Functional deficiency of alanine-glyoxylate aminotransferase in this disease leads to recurrent nephrolithiasis, nephrocalcinosis, systemic oxalosis, and kidney failure. The aim of this study was to determine the molecular etiology of kidney transplant loss in a young Tunisian individual. We present a young man with end-stage renal disease who received a kidney allograft and experienced early graft failure. There were no improvement in kidney function; he required hemodialysis and graft biopsy revealed calcium oxalate crystals, which raised suspicion of primary hyperoxaluria. Genetic study in the AGXT gene by PCR direct sequencing identified three missense changes in heterozygote state: the p. Gly190Arg mutation next to two other novels not previously described. The classification of the deleterious effect of the missense changes was developed using the summered results of four different mutation assessment algorithms, SIFT, PolyPhen, Mutation Taster, and Align-GVGD. This system classified the changes as polymorphism in one and as mutation in other. The patient was compound heterozygous mutations. Structural analysis showed that the novel mutation, p.Pro28Ser mutation, affects near the dimerization interface of AGT and positioned on binding site instead of the inhibitor, amino-oxyacetic acid (AOA). With the novel AGXT mutation, the mutational spectrum of this gene continues to broaden in our population. The diagnosis of PH1 was not recognized until after renal transplant with fatal consequences, which led us to confirm the importance of screening before planning for kidney transplantation in population with a relatively high frequency of AGXT mutation carriers.
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PMID:Identification of a novel AGXT gene mutation in primary hyperoxaluria after kidney transplantation failure. 2756 36

Oxalate (Ox) is an end-product of metabolism, important for poor solubility of its calcium salt in biological fluids. Ox can therefore be found in about 70% of urinary calculi. Hyperoxaluria (HOx) defined as Ox exceeding 0.5 mmol)/day, may cause nephrolithiasis/nephrocalcinosis and may be classified as dietary (DH), enteric (EH) or primary (PH). Fractional intestinal absorption of Ox is less than 10%, but increases to over 20% at calcium intakes below 200 mg/day. DH is often related to low-calcium diets. EH is caused by non-absorbed fatty acids which bind to calcium and lower its concentration in the intestinal lumen. Ox forms more soluble complexes with other cations and results in HOx. Similar mechanisms may cause HOx following bariatric surgery. PHs are the most severe causes of HOx. Three types have so far been described, all being autosomic recessive. PH1 is due to mutations of AGXT gene encoding liver alanine-glyoxylate aminotransferase, PH2 is caused by mutations of GR-HPR gene encoding glyoxylate reductase and PH3 by mutations of HOGA1 encoding for hydroxyl-oxoglutarate aldolase. HOx results from deficient detoxification from glyoxylate, which is oxidized to Ox. The three PHs have different severity, though not always clinically distinguishable. They are identified through genetics and, in PH1, good genotype/phenotype correlations have been established. Thanks to early biochemical and genetic diagnosis, which are crucial to either prevent progression to ESRF or choose adequate transplantation strategies, the outlook of PH patients has dramatically improved in the last decades and will furtherly do in view of new therapeutic strategies.
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PMID:[The Hyperoxalurias]. 2796 20