Context: There is an ongoing debate about whether and how fructose is involved in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). A recent experimental study showed an increased intrahepatic triglyceride (IHTG) content in mice deficient for aldolase B (aldo B-/-), the enzyme that converts fructose-1-phosphate to triose phosphates.
Objective: To translate these experimental findings to the human situation.
Design: Case-control study.
Setting: Outpatient clinic for inborn errors of metabolism.
Patients or Other Participants: Patients with hereditary fructose intolerance, a rare inborn error of metabolism caused by a defect in aldolase B (n = 15), and healthy persons matched for age, sex, and body mass index (BMI) (n =15).
Main Outcome Measure: IHTG content, assessed by proton magnetic resonance spectroscopy.
Results: IHTG content was higher in aldo B-/- patients than controls (2.5% vs 0.6%; P = 0.001) on a background of lean body mass (median BMI, 20.4 and 21.8 kg/m(2), respectively). Glucose excursions during an oral glucose load were higher in aldo B-/- patients (P = 0.043). Hypoglycosylated transferrin, a surrogate marker for hepatic fructose-1-phosphate concentrations, was more abundant in aldo B-/- patients than in controls (P <0.001). Finally, plasma beta-hydroxybutyrate, a biomarker of hepatic beta-oxidation, was lower in aldo B-/- patients than controls (P = 0.009).
Conclusions: This study extends previous experimental findings by demonstrating that aldolase B deficiency also results in IHTG accumulation in humans. It suggests that the accumulation of fructose-1-phosphate and impairment of beta-oxidation are involved in the pathogenesis.
- FATTY LIVER-DISEASE
- HEREDITARY FRUCTOSE INTOLERANCE
- INSULIN SENSITIVITY
- HEPATIC STEATOSIS