coenzyme-q10 and Metabolism--Inborn-Errors

The inherited disorders of muscle metabolism affect both substrate utilization and the final intramitochondrial oxidation through the Krebs cycle and the respiratory chain. Almost every step of these complex biochemical pathways can be affected by inborn errors, whose expression depends on peculiar tissue-specific or systemic gene expression. This review updates current knowledge in this broad field.. New inherited defects are still being discovered, such as the beta-enolase deficiency in glycogenosis type XIII and mutations in the gene encoding an esterase/lipase/thioesterase protein in Chanarin-Dorfman syndrome, a multisystem triglyceride storage disease.. Therapeutic approaches to the metabolic myopathies are still lagging behind, although remarkable observations have been made on the rare coenzyme Q10 deficiency syndrome. However, transgenic animal models may offer the opportunity both to investigate muscle pathogenesis and explore therapeutic targets. Finally, human myotoxicity may provide novel paradigms for naturally occurring muscle disorders.

Topics: Animals; Animals, Genetically Modified; Antioxidants; Coenzymes; Glycogen Storage Disease; Humans; Hypolipidemic Agents; Lipid Metabolism; Metabolism, Inborn Errors; Mitochondria, Muscle; Mitochondrial Diseases; Muscular Diseases; Mutation; Phosphopyruvate Hydratase; Ubiquinone

The syndrome of exercise intolerance, cramps, and myoglobinuria is a common presentation of metabolic myopathies and has been associated with several specific inborn errors of glycogen or lipid metabolism. As disorders in fuel utilization presumably impair muscle energy production, it was more than a little surprising that exercise intolerance and myoglobinuria had not been associated with defects in the mitochondrial respiratory chain, the terminal energy-yielding pathway. Recently, however, specific defects in complex I, complex III, and complex IV have been identified in patients with severe exercise intolerance with or without myoglobinuria. All patients were sporadic cases and all harbored mutations in protein-coding genes of muscle mtDNA, suggesting that these were somatic mutations not affecting the germ-line. Another respiratory chain defect, primary coenzyme Q10 (CoQ10) deficiency, also causes exercise intolerance and recurrent myoglobinuria, usually in conjunction with brain symptoms, such as seizures or cerebellar ataxia. Primary CoQ10 deficiency is probably due to mutations in nuclear gene(s) encoding enzymes involved in CoQ10 biosynthesis.

Topics: Adolescent; Adult; Coenzymes; Electron Transport; Electron Transport Complex I; Electron Transport Complex III; Energy Metabolism; Exercise; Exercise Tolerance; Fatty Acids; Female; Glycogen; Humans; Intracellular Membranes; Male; Metabolism, Inborn Errors; Middle Aged; Mitochondria, Muscle; Mitochondrial Myopathies; Muscle Cramp; Muscles; Myoglobinuria; NADH, NADPH Oxidoreductases; Ubiquinone

Identifying diseases displaying chronic low plasma Coenzyme Q

Topics: Adolescent; Adult; Case-Control Studies; Child; Child, Preschool; Chromatography, High Pressure Liquid; Female; Humans; Infant; Infant, Newborn; Male; Metabolism, Inborn Errors; Mucopolysaccharidoses; Mutation; Nervous System Diseases; Phenylketonurias; Retrospective Studies; Sequence Analysis, DNA; Ubiquinone; Young Adult

We evaluated coenzyme Q₁₀ (CoQ) levels in patients studied under suspicion of mitochondrial DNA depletion syndromes (MDS) (n=39). CoQ levels were quantified by HPLC, and the percentage of mtDNA depletion by quantitative real-time PCR. A high percentage of MDS patients presented with CoQ deficiency as compared to other mitochondrial patients (Mann-Whitney-U test: p=0.001). Our findings suggest that MDS are frequently associated with CoQ deficiency, as a possible secondary consequence of disease pathophysiology. Assessment of muscle CoQ status seems advisable in MDS patients since the possibility of CoQ supplementation may then be considered as a candidate therapy.

Topics: Adolescent; Ataxia; Child; Child, Preschool; Chromatography, High Pressure Liquid; DNA, Mitochondrial; Female; Humans; Infant; Infant, Newborn; Male; Metabolism, Inborn Errors; Mitochondrial Diseases; Mitochondrial Myopathies; Muscle Weakness; Muscular Diseases; Real-Time Polymerase Chain Reaction; Ubiquinone; Young Adult

The content of coenzyme Q(10) (CoQ(10)) was examined in skin fibroblasts of 10 patients with mevalonic aciduria (MVA) and of 22 patients with methylmalonic aciduria (MMA). Patients with these inborn errors of metabolism are thought to be at risk for CoQ(10) depletion either by direct inhibition of the proximal pathway of CoQ(10) synthesis (MVA) or indirectly by inhibition of mitochondrial energy metabolism (MMA). We demonstrated that CoQ(10) concentrations were not significantly different from controls in MVA patients, suggesting that there may be upregulatory effects. On the other hand the CoQ(10) content in fibroblasts of patients with MMA was significantly reduced.

Topics: Case-Control Studies; Cells, Cultured; Down-Regulation; Female; Fibroblasts; Humans; Metabolism, Inborn Errors; Methylmalonic Acid; Mevalonate Kinase Deficiency; Muscles; Ubiquinone

Three unrelated, sporadic patients with muscle coenzyme Q10 (CoQ10) deficiency presented at 32, 29, and 6 years of age with proximal muscle weakness and elevated serum creatine kinase (CK) and lactate levels, but without myoglobinuria, ataxia, or seizures. Muscle biopsy showed lipid storage myopathy, combined deficiency of respiratory chain complexes I and III, and CoQ10 levels below 50% of normal. Oral high-dose CoQ10 supplementation improved muscle strength dramatically and normalized serum CK.

Topics: Adult; Coenzymes; Creatine Kinase; Delivery, Obstetric; Disease Progression; Electron Transport Complex I; Electron Transport Complex III; Female; Humans; Lactic Acid; Lipid Metabolism; Male; Metabolism, Inborn Errors; Muscle Weakness; Muscle, Skeletal; Muscular Diseases; Pregnancy; Pregnancy Complications; Ubiquinone

Near-infrared spectrometry (NIRS) is a well-known method used to measure in vivo tissue oxygenation and hemodynamics. This method is used to derive relative measures of hemoglobin (Hb) + myoglobin (Mb) oxygenation and total Hb (tHb) accumulation from measurements of optical attenuation at discrete wavelengths. We present the design and validation of a new NIRS oxygenation analyzer for the measurement of muscle oxygenation kinetics. This design optimizes optical sensitivity and detector wavelength flexibility while minimizing component and construction costs. Using in vitro validations, we demonstrate 1) general optical linearity, 2) system stability, and 3) measurement accuracy for isolated Hb. Using in vivo validations, we demonstrate 1) expected oxygenation changes during ischemia and reactive hyperemia, 2) expected oxygenation changes during muscle exercise, 3) a close correlation between changes in oxyhemoglobin and oxymyoglobin and changes in deoxyhemoglobin and deoxymyoglobin and limb volume by venous occlusion plethysmography, and 4) a minimal contribution from movement artifact on the detected signals. We also demonstrate the ability of this system to detect abnormal patterns of tissue oxygenation in a well-characterized patient with a deficiency of skeletal muscle coenzyme Q(10). We conclude that this is a valid system design for the precise, accurate, and sensitive detection of changes in bulk skeletal muscle oxygenation, can be constructed economically, and can be used diagnostically in patients with disorders of skeletal muscle energy metabolism.

Topics: Coenzymes; Electronics; Equipment Design; Exercise; Hemoglobins; Humans; Hyperemia; Ischemia; Kinetics; Metabolism, Inborn Errors; Movement; Muscle, Skeletal; Myoglobin; Neuromuscular Diseases; Oxygen; Oxygen Consumption; Plethysmography; Reproducibility of Results; Sensitivity and Specificity; Spectroscopy, Near-Infrared; Ubiquinone