ANO10 mutations cause ataxia and coenzyme Q10 deficiency.

Inherited ataxias are heterogeneous disorders affecting both children and adults, with over 40 different causative genes, making molecular genetic diagnosis challenging. Although recent advances in next-generation sequencing have significantly improved mutation detection, few treatments exist for patients with inherited ataxia. In two patients with adult-onset cerebellar ataxia and coenzyme Q10 (CoQ10) deficiency in muscle, whole exome sequencing revealed mutations in ANO10, which encodes anoctamin 10, a member of a family of putative calcium-activated chloride channels, and the causative gene for autosomal recessive spinocerebellar ataxia-10 (SCAR10). Both patients presented with slowly progressive ataxia and dysarthria leading to severe disability in the sixth decade. Epilepsy and learning difficulties were also present in one patient, while retinal degeneration and cataract were present in the other. The detection of mutations in ANO10 in our patients indicate that ANO10 defects cause secondary low CoQ10 and SCAR10 patients may benefit from CoQ10 supplementation.

Lack of effect of coenzyme q10 on doxorubicin cytotoxicity in breast cancer cell cultures.

UNLABELLED: BACKGROUND/HYPOTHESES: Doxorubicin is a standard adjuvant therapy for early-stage breast cancer, and it significantly improves disease-free and overall survival. However, 3% to 20% of breast cancer patients develop chronic cardiomyopathic changes and congestive heart failure because of doxorubicin therapy. Doxorubicin-induced cardiotoxicity is thought to be due to the increased generation of reactive oxygen species within cardiac myocyte mitochondria. Coenzyme Q10 (CoQ10) is a lipid-soluble antioxidant that may protect against mitochondrial reactive oxygen species and thus prevent doxorubicin-induced cardiotoxicity. Despite the potential benefits of CoQ10 in preventing cardiotoxicity, it is not known if CoQ10 diminishes the antineoplastic effects of doxorubicin therapy. STUDY DESIGN: In vitro cell culture experiments. METHODS: Breast cancer cell lines (MDA-MB-468 and BT549) were tested for their ability to uptake exogenous CoQ10 using high-performance liquid chromatography. Breast cancer cell lines were then treated with doxorubicin and a range of CoQ10 concentrations to determine the effect of CoQ10 on doxorubicin's cytotoxicity. RESULTS: This study demonstrated that intracellular and mitochondrial CoQ10 concentrations increased substantially as higher exogenous concentrations were administered to breast cancer cells. CoQ10 had no effect on the ability of doxorubicin to induce apoptosis or inhibit growth or colony formation in both the cell lines tested when applied over a wide dose range, which encompassed typical basal plasma levels and plasma levels above those typically achieved by supplemented patients. CONCLUSION: The clinical testing of CoQ10 as a supplement to prevent doxorubicin-induced cardiotoxicity requires confidence that it does not decrease the efficacy of chemotherapy. These results support the hypothesis that CoQ10 does not alter the antineoplastic properties of doxorubicin. Further in vivo studies, as well as combination chemotherapy studies, would be reassuring before a large-scale clinical testing of CoQ10 as a cardioprotective drug.

Treatment of CoQ(10) deficient fibroblasts with ubiquinone, CoQ analogs, and vitamin C: time- and compound-dependent effects.

BACKGROUND: Coenzyme Q(10) (CoQ(10)) and its analogs are used therapeutically by virtue of their functions as electron carriers, antioxidant compounds, or both. However, published studies suggest that different ubiquinone analogs may produce divergent effects on oxidative phosphorylation and oxidative stress. METHODOLOGY/PRINCIPAL FINDINGS: To test these concepts, we have evaluated the effects of CoQ(10), coenzyme Q(2) (CoQ(2)), idebenone, and vitamin C on bioenergetics and oxidative stress in human skin fibroblasts with primary CoQ(10) deficiency. A final concentration of 5 microM of each compound was chosen to approximate the plasma concentration of CoQ(10) of patients treated with oral ubiquinone. CoQ(10) supplementation for one week but not for 24 hours doubled ATP levels and ATP/ADP ratio in CoQ(10) deficient fibroblasts therein normalizing the bioenergetics status of the cells. Other compounds did not affect cellular bioenergetics. In COQ2 mutant fibroblasts, increased superoxide anion production and oxidative stress-induced cell death were normalized by all supplements. CONCLUSIONS/SIGNIFICANCE: THESE RESULTS INDICATE THAT: 1) pharmacokinetics of CoQ(10) in reaching the mitochondrial respiratory chain is delayed; 2) short-tail ubiquinone analogs cannot replace CoQ(10) in the mitochondrial respiratory chain under conditions of CoQ(10) deficiency; and 3) oxidative stress and cell death can be counteracted by administration of lipophilic or hydrophilic antioxidants. The results of our in vitro experiments suggest that primary CoQ(10) deficiencies should be treated with CoQ(10) supplementation but not with short-tail ubiquinone analogs, such as idebenone or CoQ(2). Complementary administration of antioxidants with high bioavailability should be considered if oxidative stress is present.

The myopathic form of coenzyme Q10 deficiency is caused by mutations in the electron-transferring-flavoprotein dehydrogenase (ETFDH) gene.

Coenzyme Q10 (CoQ10) deficiency is an autosomal recessive disorder with heterogenous phenotypic manifestations and genetic background. We describe seven patients from five independent families with an isolated myopathic phenotype of CoQ10 deficiency. The clinical, histological and biochemical presentation of our patients was very homogenous. All patients presented with exercise intolerance, fatigue, proximal myopathy and high serum CK. Muscle histology showed lipid accumulation and subtle signs of mitochondrial myopathy. Biochemical measurement of muscle homogenates showed severely decreased activities of respiratory chain complexes I and II + III, while complex IV (COX) was moderately decreased. CoQ10 was significantly decreased in the skeletal muscle of all patients. Tandem mass spectrometry detected multiple acyl-CoA deficiency, leading to the analysis of the electron-transferring-flavoprotein dehydrogenase (ETFDH) gene, previously shown to result in another metabolic disorder, glutaric aciduria type II (GAII). All of our patients carried autosomal recessive mutations in ETFDH, suggesting that ETFDH deficiency leads to a secondary CoQ10 deficiency. Our results indicate that the late-onset form of GAII and the myopathic form of CoQ10 deficiency are allelic diseases. Since this condition is treatable, correct diagnosis is of the utmost importance and should be considered both in children and in adults. We suggest to give patients both CoQ10 and riboflavin supplementation, especially for long-term treatment.

Coenzyme Q10 levels in Prader-Willi syndrome: comparison with obese and non-obese subjects.

Coenzyme Q10 (CoQ10) is an essential component of the mitochondrial respiratory chain and an important scavenger of reactive oxygen species. Low levels are found in individuals with reduced energy expenditure, cardiac and skeletal muscle dysfunction, and mitochondrial disorders, many of these manifestations are seen in individuals with Prader-Willi syndrome (PWS). In addition, CoQ10 supplementation frequently is given to individuals with this syndrome. To determine if CoQ10 levels are decreased in PWS, we studied plasma CoQ10 levels in 16 subjects with PWS, 13 with obesity of unknown cause, and 15 subjects without obesity but of similar age and compared with body composition. Plasma CoQ10 levels were significantly decreased (P < 0.05), using several statistical approaches in subjects with PWS (0.45 +/- 0.16 microg/ml), compared to subjects without obesity (0.93 +/- 0.56 microg/ml), but not different from subjects with obesity (0.73 +/- 0.53 microg/ml). When plasma CoQ10 was normalized relative to cholesterol, triglyceride, and creatinine levels and fat and lean mass [determined by dual energy X-ray absorptiometry (DEXA)] in the subjects with either PWS or obesity, no significant differences were observed. However, a lower muscle mass was found in the PWS subjects.