What is the role of Lowe disease in Fanconi syndrome?

Updated: Feb 09, 2018
  • Author: Sahar Fathallah-Shaykh, MD; Chief Editor: Craig B Langman, MD  more...
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Answer

Bilateral congenital cataracts, glaucoma, general hypotonia, hyporeflexia, severe mental retardation, and Fanconi syndrome characterize oculocerebrorenal syndrome (Lowe syndrome).

The defect was mapped to band Xq25-26. The gene OCRL-1 was identified by positional cloning and found to have strong homology to the gene on chromosome 1 for human inositol polyphosphate-5-phosphatase found in the Golgi apparatus. This enzyme removes the 5-phosphate from 1,4,5-inositol triphosphate, which may inactivate the phosphatidyl-inositol pathway. The relationship between this presumed effect and undersulfation of glycosaminoglycans found in patients with Lowe syndrome is unclear.

Unlike the cataracts, which are always present at birth, abnormalities in renal function may become apparent only after a few weeks or a few months of extrauterine life. Aminoaciduria, with relative sparing of branch-chain amino acids, is a constant feature of the syndrome. Glucosuria is not always present and its severity varies. Phosphate and potassium reabsorption follow a pattern similar to that of glucose. Acidosis, which is caused by a defect in the proximal reabsorption of bicarbonate, is almost always present. Cognitive, behavioral, and neuromuscular abnormalities vary in frequency and severity. Seizures occur in about 50% of patients. The renal disease advances with age, leading to chronic renal failure in adulthood. The treatment is symptomatic.


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