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Hereditary fructose intolerance is an autosomal recessive disorder due to a deficiency of fructose-1-phosphate aldolase activity, which results in an accumulation of fructose-1-phosphate in the liver, kidney, and small intestine. This disorder may be as common as 1 in 20,000 in some European countries. Homozygous neonates remain clinically healthy until confronted with dietary sources of fructose, usually occurring at the time of weaning when fructose or sucrose is added to the diet. Clinical symptoms include severe abdominal pain, vomiting, and hypoglycemia following ingestion of fructose or other sugars metabolised through fructose-1-phosphate. Prolonged fructose ingestion in infants leads ultimately to hepatic and/or renal failure and death. Patients develop a strong distaste for sweet food. The defect resides in aldolase B which catalyzes the cleavage of fructose-1-phosphate to form dihydroxyacetone phosphate and D-glyceraldehyde. Evidence for genetic heterogeneity was considered: both structural and controller mutations may exist, as well as more than one type of structural mutation. Diagnosis methods include an enzymatic liver biopsy assay to determine aldolase activity ; or a fructose tolerance test: fructose is injected intraveniously under controlled conditions where acute glucose, fructose, and phosphate levels are monitored. |