Fructose Intolerance

Fructose Intolerance

Hereditary fructose intolerance (HFI) is an inborn error of fructose metabolism caused by a deficiency of the enzyme aldolase B. Individuals affected with HFI are asymptomatic until they ingest fructose, sucrose, or sorbitol. If fructose is ingested, the enzymatic block at aldolase B causes an accumulation of fructose-1-phosphate. This accumulation has downstream effects on gluconeogenesis and regeneration of adenosine triphosphate (ATP). Symptoms of HFI include vomiting, hypoglycemia, jaundice, hemorrhage, hepatomegaly, hyperuricemia and potentially kidney failure. While HFI is not clinically a devastating condition, there are reported deaths in infants and children as a result of the metabolic consequences of HFI. Death in HFI is always associated with problems in diagnosis.

HFI is an autosomal recessive condition caused by mutations in the ALDOB gene, located at 9q22.3. Diagnosis of HFI is typically suspected based on dietary history, especially in infants who become symptomatic after breast feeding is supplemented by fructose containing foods. This suspicion is typically confirmed by molecular analysis. Treatment of HFI is based around strict avoidance of fructose in the diet. Older patients with HFI typically self-select a diet low in fructose, even before being diagnosed.