alpha-Tocopherol/lipid ratio in blood is decreased in patients with Leber's hereditary optic neuropathy and asymptomatic carriers of the 11778 mtDNA mutation

Objectives-Leber's hereditary optic neuropathy (LHON) is a maternally inher ited disease characterised by acute or subacute bilateral visual loss in yo ung patients. The primary aetiological event is a mutation in the mitochond rial genome (mtDNA) affecting in most cases mtDNA-encoded subunits of the r espiratory chain NADH: coenzyme Q oxidoreductase (complex I). The impaired function of complex I leads to a decline in mitochondrial energy production and enhances free radical generation. Methods-The concentrations of some non-enzymatic antioxidants (alpha -tocop herol, beta -carotene, lycopene, glutathione, free sulphydryl groups) and t he lipid peroxides in the blood of patients with LHON, carriers with homopl asmic DNA mutation at 11 778, and controls were investigated using high per formance Liquid chromatography and spectrophotometric methods to assess the function of their antioxidant defence systems. Results-The alpha -tocopherol/cholesterol+triglyceride ratio was significan tly reduced (p<0.05) both in the patients and asymptomatic carriers. The co ncentrations of the other antioxidants and the lipid peroxides were not dif ferent from those of control subjects. Conclusion-The low concentration of plasma <alpha>-tocopherol most probably reflects the consumption of the antioxidant by the affected tissues. Furth ermore, it suggests that alpha -tocopherol may be the primary scavenger mol ecule against the free radicals induced by complex I deficiency.