What causes galactosemia in Fanconi syndrome?

Updated: Feb 09, 2018
  • Author: Sahar Fathallah-Shaykh, MD; Chief Editor: Craig B Langman, MD  more...
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Galactosemia is caused by a deficiency in the activity of galactose-1-phosphate uridyltransferase. This enzyme catalyzes the reaction between galactose-1-phosphate and uridine-diphosphate-glucose to create uridine-diphosphate-galactose and glucose-1-phosphate. Deficiency of galactose-1-phosphate uridyltransferase leads to the accumulation of galactose-1-phosphate in various organs, including the liver, kidneys, brain, and ovaries, as well as the lenses of the eye. This accumulation only occurs when children with galactose-1-phosphate uridyltransferase deficiency receive milk, which is high in lactose, a major source of galactose.

Affected infants develop vomiting, diarrhea, and failure to thrive. Many of them become jaundiced because of increased levels of unconjugated bilirubin. The clinical picture is complicated by cataracts, splenomegaly, and hepatomegaly, leading to cirrhosis. Hyperaminoaciduria, albuminuria, and galactosuria (but not glucosuria) appear early in the course of the disease.

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