Genetic Basis for Correction of Very-Long-Chain Acyl–Coenzyme A Dehydrogenase Deficiency by Bezafibrate in Patient Fibroblasts: Toward a Genotype-Based Therapy

Abstract

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.

Carnitine-Acylcarnitine Translocase Deficiency: Experience with Four Cases in Spain and Review of the Literature

“…This approach has already been used successfully in other FAO defects such as CPTII or VLCAD (Djouadi et al 2003;Gobin-Limballe et al 2007;Bonnefont et al 2009). …”

Delineating the role of alterations in lipid metabolism to the pathogenesis of inherited skeletal and cardiac muscle disorders

“…The infantile onset form has cardiac defects with hypertrophic cardiomyopathy, the childhood onset form has repeated episodes of hypoglycemia, and the adolescent/adult onset has intermittent rhabdomyolysis (207)(208)(209). The mutational spectrum of VLCAD defi ciency is very wide, with over 80 mutations identifi ed in the VLCAD gene and none of them being prevalent ( 210,211 ). To fi nd a possible genotype-phenotype relationship, these mutations have been grouped into two categories: null mutations and missense mutations ( 210 ).…”

“…To fi nd a possible genotype-phenotype relationship, these mutations have been grouped into two categories: null mutations and missense mutations ( 210 ). Null mutations that result in no residual VLCAD enzyme activity have generally been associated with the infantile phenotype, whereas missense mutations that result in a residual enzyme activity have been associated with the childhood and early adulthood phenotypes ( 210,211 ). However, recently an overlap between these phenotypes was observed as a novel compound-heterozygote missense mutation of exons 9 and 10 in VLCAD that has been associated with the perinatal-onset form and repeated episodes of rhabdomyolysis during infancy and early childhood.…”

Strategies for Correcting Very Long Chain Acyl-CoA Dehydrogenase Deficiency

“…Beyond this standard of care approach, an experimental oil called triheptanoin (a triglyceride with three heptanoic or seven carbon fatty acids esterified to a glycerol backbone) is under clinical trial to decrease muscle pain and to improve heart function (identifiers, NCT01379625 and NCT01886378). Moreover, bezafibrate, which is effective in most types of primary and secondary dyslipidemia, has been shown to restore FAO capacities in VLCAD-deficient patient fibroblasts by activation of the peroxisome proliferator activated receptor, leading to stimulation of residual enzyme activity (6).…”