Hyperoxaluria


Hyperoxaluria
Hyperoxaluria
Classification and external resources

Oxalate
ICD-10 E74.8
ICD-9 271.8
DiseasesDB 31642
eMedicine med/3027
MeSH D006959

Hyperoxaluria is an excessive urinary excretion of oxalate. Individuals with hyperoxaluria often have calcium oxalate kidney stones. Sometimes called Bird's disease, after Golding Bird who was first to describe the condition.

Contents

Causes

Type I (PH1) is associated with AGXT protein, a key enzyme involved in breakdown of oxalate. PH1 is also an example of a protein mistargeting disease wherein AGXT shows a trafficking defect: instead of being trafficked to peroxisomes, it is targeted to mitochondria where it is metabolically deficient despite being catalytically active. Type II is associated with GRHPR.[1] It is also a complication of jejunoileal bypass, or in any patient who has lost much of the ileum with an intact colon. This is due to excessive absorption of oxalate from the colon.[2]

Treatment

The main therapeutic approach to primary hyperoxaluria is still restricted to symptomatic treatment, i.e. kidney transplantation once the disease has already reached mature or terminal stages. However, through genomics and proteomics approaches, efforts are currently being made to elucidate the kinetics of AGXT folding which has a direct bearing on its targeting to appropriate subcellular localization. Secondary hyperoxaluria is much more common than primary hyperoxaluria and should be treated by limiting dietary oxalate and providing calcium supplementation. A child with primary hyperoxaluria was treated with a liver and kidney transplant.[3] Favorable outcome is more likely if a kidney transplant is complemented with a liver transplant given that the disease originates in the liver.

Controversy

Perhaps the key difficulty in understanding pathogenesis of primary hyperoxaluria, or more specifically, why AGXT ends up in mitochondria instead of peroxisomes, stems from AGXT's somewhat peculiar evolution. Namely, prior to its current peroxysomal 'destiny', AGXT indeed used to be bound to mitochondria. AGXT's peroxisomal targeting sequence is uniquely specific for mammalian species suggesting the presence of additional peroxisomal targeting information elsewhere in the AGT molecule. As AGXT was redirected to peroxisomes over the course of evolution, it is plausible that its current aberrant localization to mitochondria owes to some hidden molecular signature in AGXT's spatial configuration unmasked by PH1 mutations affecting the AGXT gene. It is in this sense that we could conditionally understand PH1 as a sort of atavism acting on a molecular level. However, this should be taken as a metaphore with all the caveats of metaphoric thinking applied to science.

  • Primary hyperoxaluria
  • Enteric hyperoxaluria
  • Idiopathic hyperoxaluria
  • Oxalate poisoning

External links

References



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Look at other dictionaries:

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  • hyperoxaluria — …   Useful english dictionary

  • enteric hyperoxaluria — hyperoxaluria occurring after extensive resection or disease of the ileum and resulting from excessive absorption of oxalate from the colon, with formation of calcium oxalate calculi in the urinary tract …   Medical dictionary

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  • primary hyperoxaluria — an autosomal recessive disorder of glyoxylate metabolism, characterized by urinary excretion of large amounts of oxalate and deposition of calcium oxalate in the tissues, especially the kidney, with nephrolithiasis, nephrocalcinosis, and renal… …   Medical dictionary

  • AGXT — Alanine glyoxylate aminotransferase (oxalosis I; hyperoxaluria I; glycolicaciduria; serine pyruvate aminotransferase), also known as AGXT, is a human gene.cite web | title = Entrez Gene: AGXT alanine glyoxylate aminotransferase (oxalosis I;… …   Wikipedia

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  • GRHPR — Glyoxylate reductase/hydroxypyruvate reductase, also known as GRHPR, is a human gene.cite web | title = Entrez Gene: GRHPR glyoxylate reductase/hydroxypyruvate reductase| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene Cmd=ShowDetailView… …   Wikipedia

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