Received on February 10, 2006
Accepted on April 28, 2006

Lipids, Lipoproteins, and Cardiovascular Risk Factors

Assessment of Tocopherol Metabolism and Oxidative Stress in Familial Hypobetalipoproteinemia

¹ Department of Core Clinical Pathology and Biochemistry, PathWest Laboratory Medicine WA, Royal Perth Hospital, Perth, WA, Australia, and School of Medicine and Pharmacology, University of Western Australia. Crawley, WA, Australia
² Department of Core Clinical Pathology and Biochemistry, PathWest Laboratory Medicine WA, Royal Perth Hospital, Perth, WA, Australia, and School of Surgery and Pathology, University of Western Australia. Crawley, WA, Australia
³ School of Medicine and Pharmacology, University of Western Australia. Crawley, WA, Australia

^* To whom correspondence should be addressed. E-mail: john.burnett{at}health.wa.gov.au.

Background: Vitamin E supplementation has been recommended for persons with familial hypobetalipoproteinemia (FHBL), a rare disorder of lipoprotein metabolism that leads to low serum -tocopherol and decreased LDL-cholesterol and apolipoprotein (apo) B. We examined the effect of truncated apoB variants on vitamin E metabolism and oxidative stress in persons with FHBL.

Methods: We studied 9 individuals with heterozygous FHBL [mean (SE) age, 40 (5) years; body mass index (BMI), 27 (10) kg/m²] and 7 normolipidemic controls [age, 41 (5) years; BMI, 25 (2) kg/m²]. We also studied 3 children--2 with homozygous FHBL (apoB-30.9) and 1 with abetalipoproteinemia--who were receiving -tocopherol supplementation. We used HPLC with electrochemical detection to measure - and -tocopherol in serum, erythrocytes, and platelets, and gas chromatography-mass spectrometry to measure F₂-isoprostanes and tocopherol metabolites in urine as markers of oxidative stress and tocopherol intake, respectively.

Results: Compared with controls, persons with FHBL had significantly lower fasting plasma concentrations of total cholesterol [2.4 (0.2) vs 4.7 (0.2) mmol/L], triglycerides [0.5 (0.1) vs 0.9 (0.1) mmol/L], LDL-cholesterol [0.7 (0.1) vs 2.8 (0.3) mmol/L], apoB [0.23 (0.02) vs 0.84 (0.08) g/L], -tocopherol [13.6 (1.0) vs 28.7 (1.4) µmol/L], and -tocopherol [1.0 (0.1) vs 1.8 (0.3) µmol/L] (all P <0.03). Erythrocyte -tocopherol was decreased [5.0 (0.2) vs 6.0 (0.3) µmol/L; P <0.005], but we observed no differences in lipid-adjusted serum tocopherols, erythrocyte -tocopherol, platelet - or -tocopherol, urinary F₂-isoprostanes, or tocopherol metabolites.

Conclusion: Taken together, our findings do not support the recommendation that persons with heterozygous FHBL receive vitamin E supplementation.