Long-term follow-up of bezafibrate treatment in patients with the myopathic form of carnitine palmitoyltransferase 2 deficiency.

Carnitine palmitoyltransferase 2 (CPT2) deficiency is a rare mitochondrial fatty acid oxidation (FAO) disorder characterized by myalgia, exercise intolerance, and rhabdomyolysis. We evaluate the efficacy of bezafibrate (BZ), a hypolipidemic drug, as a treatment for this form of CPT2 deficiency. A pilot trial was conducted with BZ in six patients for 6 months. There was a follow-up period of 3 years. The oxidation rates of the long-chain fatty acid derivative palmitoyl-CoA, measured in the mitochondria of the patients' muscles, were markedly lower than normal before treatment and increased significantly (+39 to +206%; P = 0.028) in all patients after BZ treatment. The evaluation of the therapeutic effects by the patients themselves (using the Short Form Health Survey (SF-36)), as well as by the physicians, indicated an improvement in the condition of the patients; there was an increase in physical activity and a decline in muscular pain. The results suggest that BZ has a therapeutic effect in the muscular form of CPT2 deficiency.

Genetic basis for correction of very-long-chain acyl-coenzyme A dehydrogenase deficiency by bezafibrate in patient fibroblasts: toward a genotype-based therapy.

Very-long-chain acyl-coenzyme A dehydrogenase (VLCAD) deficiency is an inborn mitochondrial fatty-acid beta-oxidation (FAO) defect associated with a broad mutational spectrum, with phenotypes ranging from fatal cardiopathy in infancy to adolescent-onset myopathy, and for which there is no established treatment. Recent data suggest that bezafibrate could improve the FAO capacities in beta-oxidation-deficient cells, by enhancing the residual level of mutant enzyme activity via gene-expression stimulation. Since VLCAD-deficient patients frequently harbor missense mutations with unpredictable effects on enzyme activity, we investigated the response to bezafibrate as a function of genotype in 33 VLCAD-deficient fibroblasts representing 45 different mutations. Treatment with bezafibrate (400 microM for 48 h) resulted in a marked increase in FAO capacities, often leading to restoration of normal values, for 21 genotypes that mainly corresponded to patients with the myopathic phenotype. In contrast, bezafibrate induced no changes in FAO for 11 genotypes corresponding to severe neonatal or infantile phenotypes. This pattern of response was not due to differential inductions of VLCAD messenger RNA, as shown by quantitative real-time polymerase chain reaction, but reflected variable increases in measured VLCAD residual enzyme activity in response to bezafibrate. Genotype cross-analysis allowed the identification of alleles carrying missense mutations, which could account for these different pharmacological profiles and, on this basis, led to the characterization of 9 mild and 11 severe missense mutations. Altogether, the responses to bezafibrate reflected the severity of the metabolic blockage in various genotypes, which appeared to be correlated with the phenotype, thus providing a new approach for analysis of genetic heterogeneity. Finally, this study emphasizes the potential of bezafibrate, a widely prescribed hypolipidemic drug, for the correction of VLCAD deficiency and exemplifies the integration of molecular information in a therapeutic strategy.