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Query: UMLS:C0020500 (hyperoxaluria)
 912 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Zellweger spectrum disorders (ZSDs) are characterized by a generalized loss of peroxisomal functions caused by deficient peroxisomal assembly. Clinical presentation and survival are heterogeneous. Although most peroxisomal enzymes are unstable in the cytosol of peroxisome-deficient cells of ZSD patients, a few enzymes remain stable among which alanine:glyoxylate aminotransferase (AGT). Its deficiency causes primary hyperoxaluria type 1 (PH1, MIM 259900), an inborn error of glyoxylate metabolism characterized by hyperoxaluria, nephrocalcinosis, and renal insufficiency. Despite the normal level of AGT activity in ZSD patients, hyperoxaluria has been reported in several ZSD patients. We observed the unexpected occurrence of renal stones in a cohort of ZSD patients. This led us to perform a study in this cohort to determine the prevalence of hyperoxaluria in ZSDs and to find clinically relevant clues that correlate with the urinary oxalate load. We reviewed medical charts of 31 Dutch ZSD patients with prolonged survival (>1 year). Urinary oxalate excretion was assessed in 23 and glycolate in 22 patients. Hyperoxaluria was present in 19 (83%), and hyperglycolic aciduria in 14 (64%). Pyridoxine treatment in six patients did not reduce the oxalate excretion as in some PH1 patients. Renal involvement with urolithiasis and nephrocalcinosis was present in five of which one developed end-stage renal disease. The presence of hyperoxaluria, potentially leading to severe renal involvement, was statistically significant correlated with the severity of neurological dysfunction. ZSD patients should be screened by urinalysis for hyperoxaluria and renal ultrasound for nephrocalcinosis in order to take timely measures to prevent renal insufficiency.
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PMID:High incidence of hyperoxaluria in generalized peroxisomal disorders. 1662 44

Genetic disorders of mineral metabolism cause urolithiasis, renal disease, and osteodystrophy. Most are rare, such that the full spectrum of clinical expression is difficult to appreciate. Diagnosis is further complicated by overlap of clinical features. Dent's disease and primary hyperoxaluria, inherited causes of calcium urolithiasis, are both associated with nephrocalcinosis and urolithiasis in early childhood and renal failure that can occur at any age but is seen more often in adulthood. Bone disease is an inconsistent feature of each. Dent's disease is caused by mutations of the CLCN-5 gene with impaired kidney-specific CLC-5 chloride channel expression in the proximal tubule, thick ascending limb of Henle, and the collecting ducts. Resulting hypercalciuria and proximal tubule dysfunction, including phosphate wasting, are primarily responsible for the clinical manifestations. Low-molecular-weight proteinuria is characteristic. Definitive diagnosis is made by DNA mutation analysis. Primary hyperoxaluria, type I, is due to mutations of the AGXT gene leading to deficient hepatic alanine-glyoxylate aminotransferase activity. Marked overproduction of oxalate by hepatic cells results in the hyperoxaluria responsible for clinical features. Definitive diagnosis is by liver biopsy with measurement of enzyme activity, with DNA mutation analysis used increasingly as mutations and their frequency are defined. These disorders of calcium urolithiasis illustrate the value of molecular medicine for diagnosis and the promise it provides for innovative and more effective future treatments.
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PMID:Stones, bones, and heredity. 1680 Nov 62

Excessive urinary oxalate excretion, termed hyperoxaluria, may arise from inherited or acquired diseases. The most severe forms are caused by increased endogenous production of oxalate related to one of several inborn errors of metabolism, termed primary hyperoxaluria. Recurrent kidney stones and progressive medullary nephrocalcinosis lead to the loss of kidney function, requiring dialysis or transplantation, accompanied by systemic oxalate deposition that is termed systemic oxalosis. For most primary hyperoxalurias, accurate diagnosis leads to the use of therapies that include pyridoxine supplementation, urinary crystallisation inhibitors, hydration with enteral fluids and, in the near future, probiotic supplementation or other innovative therapies. These therapies have varying degrees of success, and none represent a cure. Organ transplantation results in reduced patient and organ survival when compared with national statistics. Exciting new approaches under investigation include the restoration of defective enzymatic activity through the use of chemical chaperones and hepatocyte cell transplantation, or recombinant gene therapy for enzyme replacement. Such approaches give hope for a future therapeutic cure for primary hyperoxaluria that includes correction of the underlying genetic defect without exposure to the life-long dangers associated with organ transplantation.
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PMID:Hyperoxaluria and systemic oxalosis: current therapy and future directions. 1702 Apr 15

Mutations in the alanine-glyoxylate amino transferase gene (AGXT) are responsible for primary hyperoxaluria type I, a rare disease characterized by excessive hepatic oxalate production that leads to renal failure. We generated a null mutant mouse by targeted mutagenesis of the homologous gene, Agxt, in embryonic stem cells. Mutant mice developed normally, and they exhibited hyperoxaluria and crystalluria. Approximately half of the male mice in mixed genetic background developed calcium oxalate urinary stones. Severe nephrocalcinosis and renal failure developed after enhancement of oxalate production by ethylene glycol administration. Hepatic expression of human AGT1, the protein encoded by AGXT, by adenoviral vector-mediated gene transfer in Agxt(-/-) mice normalized urinary oxalate excretion and prevented oxalate crystalluria. Subcellular fractionation and immunofluorescence studies revealed that, as in the human liver, the expressed wild-type human AGT1 was predominantly localized in mouse hepatocellular peroxisomes, whereas the most common mutant form of AGT1 (G170R) was localized predominantly in the mitochondria.
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PMID:Alanine-glyoxylate aminotransferase-deficient mice, a model for primary hyperoxaluria that responds to adenoviral gene transfer. 1711 Apr 43

This retrospective survey examines the etiology of nephrocalcinosis (NC) in 40 patients (26 boys), over an 8-year period. The median age at onset of symptoms and presentation was 36 months and 72 months, respectively. Clinical features included marked failure to thrive (82.5%), polyuria (60%) and bony deformities (52.5%). The etiology of NC included distal renal tubular acidosis (RTA) in 50% patients and idiopathic hypercalciuria and hyperoxaluria in 7.5% each. Other causes were Bartter syndrome, primary hypomagnesemia with hypercalciuria, severe hypothyroidism and vitamin D excess. No cause for NC was found in 12.5% patients. Specific therapy, where possible, ameliorated the biochemical aberrations, although the extent of NC remained unchanged. At a median (range) follow up of 35 (14-240) months, glomerular filtration rate (GFR) had declined from 82.0 (42-114) ml/min per 1.73 m2 body surface area to 70.8 (21.3-126.5) ml/min per 1.73 m2 body surface area (P = 0.001). Our findings confirm that, even with limited diagnostic facilities, protocol-based evaluation permits determination of the etiology of NC in most patients.
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PMID:Etiology of nephrocalcinosis in northern Indian children. 1728 94

Hyperoxaluria can lead to multiple pathologic conditions such as recurrent urolithiasis, oxalosis, nephrocalcinosis and even renal failure, but there is no known oxalate-degrading pathway in the human body, and current therapeutic options for patients with hyperoxaluria are limited. Oxalyl-CoA decarboxylase and formyl-CoA transferase are the key enzymes in the oxalate catabolism of Oxalobacter formigenes which dwell in the intestine of vertebrates and have an important symbiotic relationship with their hosts. The aim of this study was to insert the oxalate-degrading enzyme genes into human embryo kidney (HEK) 293 cells and to evaluate if the oxalate-degrading enzymes could be expressed in these cells and keep their enzyme activity. We present here the cloning of the two genes from O. formigenes and their subsequent expression in HEK293 cells. The results showed that the expression of oxalyl-CoA decarboxylase and formyl-CoA transferase was confirmed by RT-PCR and Western blotting, and the proteins were located in the cytoplasm of transfected cells. Furthermore, the transfected cells were capable to a certain degree of degrading oxalate. These findings suggest that the transfer of oxalate-degrading enzyme genes into human cells is possibly a potential candidate for the gene therapy of hyperoxaluria.
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PMID:Stable expression of the oxc and frc genes from Oxalobacter formigenes in human embryo kidney 293 cells: implications for gene therapy of hyperoxaluria. 1778 82

Primary distal renal tubular acidosis (dRTA) is an inherited disease characterized by the inability of the distal tubule to lower urine pH <5.50 during systemic acidosis. We report two male siblings who presented with severe hyperchloremic metabolic acidosis, high urinary pH, nephrocalcinosis, growth retardation, sensorineural hearing loss, and hypokalemic paralysis. Laboratory investigations revealed proximal tubular dysfunction (low molecular weight proteinuria, generalized hyperaminoaciduria, hypophosphatemia with hyperphosphaturia, and hypouricemia with hyperuricosuria). There was significant hyperoxaluria and laboratory evidence for mild rhabdomyolysis. Under potassium and alkali therapy, proximal tubular abnormalities, muscular enzymes, and oxaluria normalized. A homozygous mutation in the ATP6V1B1 gene, which is responsible for dRTA with early hearing loss, was detected in both siblings. In conclusion, proximal tubular dysfunction and hyperoxaluria may be found in children with dRTA and are reversible under appropriate therapy.
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PMID:Atypical presentation of distal renal tubular acidosis in two siblings. 1838 70

The primary hyperoxalurias (PHs) are rare disorders of glyoxylate metabolism in which specific hepatic enzyme deficiencies result in overproduction of oxalate. Due to the resulting severe hyperoxaluria, recurrent urolithiasis or progressive nephrocalcinosis are principal manifestations. End stage renal failure frequently occurs and is followed by systemic oxalate deposition along with its devastating effects. Due to the lack of familiarity with PHs and their heterogeneous clinical expressions, the diagnosis is often delayed until there is advanced disease. In recent years, improvements in medical management have been associated with better patient outcomes. Although there are several therapeutic options that can help prevent early kidney failure, the only curative treatment to date is combined liver-kidney transplantation in patients with type I PH. Promising areas of investigation are being identified. Knowledge of the spectrum of disease expression, early diagnosis, and initiation of treatment before renal failure are essential to realize a benefit for patients.
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PMID:The primary hyperoxalurias. 1922 56

We report 3 cases of primary oxalosis with nephrocalcinosis and severe renal failure. Extrarenal involvement was noted in bones in 3 cases, the heart in 2 cases, the central nervous system in 2 cases, the skin in 1 case and the eye in 1 case. The 3 patients presented with acute digestive disorders. Ultrasonography and CT scans showed digestive wall calcifications in addition to the classic appearance of primary oxalosis such as nephrocalcinosis or bone involvement. Primary hyperoxaluria is characterized by a calcium deposit in different tissues, mainly in kidneys. Digestive wall involvement has never been reported in the literature. Primary oxaluria should be considered in the presence of such a deposit in the gut wall.
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PMID:[Exceptional digestive location of crystal deposits in primary hyperoxaluria]. 1974 2

PH1 is an inborn error of the metabolism in which a functional deficiency of the liver-specific peroxisomal enzyme, AGT, causes hyperoxaluria and hyperglycolic aciduria. Infantile PH1 is the most aggressive form of this disease, leading to early nephrocalcinosis, systemic oxalosis, and end-stage renal failure. Infantile PH1 is rapidly fatal in children unless timely liver-kidney transplantation is performed to correct both the hepatic enzyme defect and the renal end-organ damage. The surgical procedure can be further complicated in infants and young children, who are at higher risk for vascular anomalies, such as IVC thrombosis. Although recently a limited number of children with IVC thrombosis have underwent successful kidney transplantation, successful multi-organ transplantation in a child with complete IVC thrombosis is quite rare. We report here the interesting and technically difficult case of a three-yr-old girl with a complete thrombosis of the IVC, who was the recipient of combined split liver and kidney transplantation for infantile PH1. Although initial delayed renal graft function with mild-to-moderate acute rejection was observed, the patient rapidly regained renal function after steroid boluses, and was soon hemodialysis-independent, with good diuresis. Serum and plasma oxalate levels progressively decreased; although, to date they are still above normal. Hepatic and renal function indices were at, or approaching, normal values when the patient was discharged 15-wk post-transplant, and the patient continues to do well, with close and frequent follow-up. This is the first report of a successful double-organ transplant in a pediatric patient presenting with infantile PH1 complicated by complete IVC thrombosis.
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PMID:Combined split liver and kidney transplantation in a three-year-old child with primary hyperoxaluria type 1 and complete thrombosis of the inferior vena cava. 1979 27


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