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Clinical and biochemical correlations in mitochondrial myopathies treated with coenzyme Q10.

We tested the efficacy of coenzyme Q10 (ubidecarenone, CoQ10) therapy in patients with Kearns-Sayre syndrome and other mitochondrial myopathies with chronic progressive external ophthalmoplegia (CPEO). We treated seven patients for 1 year with daily oral administration of 120 mg of CoQ10. Throughout the treatment most of our patients showed a progressive reduction of serum lactate and pyruvate levels following standard muscle exercise and generally improved neurologic functions. The ECG and echocardiogram showed no significant changes in our patients. None of our patients showed any improvement in ptosis and CPEO.

Adolescent↗

Diabetes associated with a novel 3264 mitochondrial tRNA(Leu)(UUR) mutation.

OBJECTIVE: To present a novel mitochondrial DNA mutation in a diabetic family RESEARCH DESIGN AND METHODS: The proband was a 64-year-old man. In the family, diabetes was maternally inherited. He had diabetes, cerebellar ataxia, cervical lipoma, hearing loss, olfactory dysfunction, ophthalmoplegia, and facial nerve bilateral palsy. On examination, early insulin secretion was blunted, and the M value on glucose clamp test was low. In muscle, ragged red fibers were not found. T-to-C mutation at position 3264 was detected in the proband (0.5% mutant DNAs in leukocyte and 30% in muscle), but was not detected in 201 normal individuals. RESULTS: Heteroplasmy of mutation, maternal inheritance of diabetes, and symptoms related to mitochondrial dysfunction suggest the pathogenecity of this 3264 mutation. As for diabetes etiology, both impaired insulin secretion and decreased insulin sensitivity seem to be important. In phenotypic characteristics, the combination of cerebellar ataxia and lipoma is a symptom sometimes found in myoclonic epilepsy and ragged red fibers (MERRFs). Ophthamoplegia is a symptom of chronic progressive external ophthalmoplegia (CPEO). These suggest that our proband had phenotypic overlap with MERRF and CPEO. Conversely, facial nerve bilateral palsy is a rare finding. The pictures that focused on his cranial nerves were thus unique, suggesting the heterogeneity of mitochondrial DNA (mtDNA)-related diabetes. CONCLUSIONS: A novel 3264 mitochondrial DNA mutation in diabetes gives new insight to the etiology of mitochondrial diabetes. Its pathogenecity supports the belief that the tRNA(Leu)(UUR) gene is an etiological hot spot of mitochondrial diseases.

DNA, Mitochondrial↗

Molecular epidemiologic study of mitochondrial DNA mutations in patients with mitochondrial diseases in Taiwan.

We report an 8-year molecular study of mitochondrial DNA (mtDNA) mutations in patients with mitochondrial diseases in Taiwan. One hundred and seventy-seven patients met the diagnostic criteria of mitochondrial disease and were recruited into the study. The results showed that 32 patients, including 25 with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome, one with Kearns-Sayre syndrome (KSS), one with diabetes mellitus and deafness, and five with chronic progressive external ophthalmoplegia (CPEO), harbored the A3243G mtDNA mutation. The A8344G mutation was found in nine patients, all of whom suffered from myoclonic epilepsy and ragged-red fibers (MERRF) syndrome. The G11778A mtDNA mutation was found in 18 of 22 patients with Leber's hereditary optic neuropathy. The T8993C and T8993G mutations were found, respectively, in one and two patients with Leigh syndrome. Large-scale deletions of mtDNA were found in 17 patients with CPEO, one with KSS, one with MELAS, and two with MERRF syndrome. The mtDNA mutations in patients with each of the mitochondrial diseases found in Taiwan were restricted mainly to a single site, while those reported for the same diseases in other ethnic groups occurred in many sites. Furthermore, significant levels of additional mtDNA mutations occurred in some patients with mitochondrial encephalomyopathies. We suggest that these additional (or secondary) mtDNA mutations are generated as a consequence of the preexisting primary mtDNA mutations and may contribute to the age-dependent progressive deterioration characteristic of mitochondrial diseases.

Adolescent↗

[Partial deletion of mitochondrial DNA in mitochondrial encephalomyopathies].

OBJECTIVE: To characterize the deletions of mitochondrial DNA (mtDNA) in Chinese patients with Kearns-Sayre syndrome (KSS) and chronic progressive external ophthalmolegia (CPEO) and identify deletion mutations of mtDNA be the etiology of these diseases. METHODS: Patients and preparation of total DNA: Two patients with KSS and two with CPEO and ten with other mitochondrial myopathies or encephalomyopathies were determined by histological and biochemical assays. Total DNA was isolated from 100 mg to 150 mg of frozen muscle obtained by biopsy using the methods described by Zeviani et al. (1988). Preparation of mtDNA probes: MtDNA were isolated and purified according to Palva's method (1985). The mtDNA was linearized by digestion with the restriction endonuclease Pvu II and separated by electrophoresis through low melting agarose gel. The 16.5 kb DNA band was recovered from the gel and labeled with alpha-p32 dCTP by random primer labeling. Southern blot analysis: Portions of five micrograms total DNA obtained from the patients and controls were digested with Pvu II, EcoR I, Hind III And Xba I respectively. The digested DNA was separated by agarose gel electrophoresis and transferred to nitrocellulose membrane and then hybridized with P32 labeled mtDNA as previously described (Zhang, 1991). RESULTS: A large-scale deletions of mtDNA were identified in two patients with KSS and two patients with CEPO. The deletions ranged in size from 2.4 kb to 5.5 kb. The proportion of mutated mtDNA in each patients ranged from 54.6% to 84.6% of total mtDNA. No detectable deletions were found in mtDNA of ten patients with other mitochondrial myopathies or encepholomyopathies and normal controls. CONCLUSIONS: Deletions of mtDNA were found in all KSS and CEPO patients detected. These results supported The view point of the deletions are important causes of physical defect in KSS and CEPO.

DNA, Mitochondrial↗

Mitochondrial gene defect in patients with chronic progressive external ophthalmoplegia.

OBJECTIVE: To detect the gene defect of mitochondrial DNA (mtDNA) from skeletal muscles in 2 patients with chronic progressive external ophthalmoplegia (CPEO). METHODS: After extraction of mtDNA, Southern hybridization was performed after restrictive digestion by Pvu II, EcoRI, Hind III, and Sacl. Then, we carried out polymerase chain reaction (PCR) and the enzyme digestion of the PCR products. Finally, mtDNA sequencing was done by automatic DNA sequence analyzer. RESULTS: In case 1, a 5 kb deletion was found by Southern blot analysis and PCR. And dosage analysis showed a heteroplasmic change with 44% mtDNAs deleted. In case 2, PCR plus restriction endonuclease Pvu II digestion demonstrated a mutation which was confirmed by DNA sequencing to be a single base substitution (T-->C) inducing a novel Pvu II site around 10,909 on mtDNA sequence. The laser image analyzer measurement revealed the mutation was almost homologous (99.4% mutant). CONCLUSIONS: In case 1, a 5 kb deletion found in mtDNA is called "common deletion" according to the literature. In case 2, a novel Pvu II site was found. It seems to be a de novo point mutation affecting ND4 in published CPEO research and is first reported in Chinese population. This point mutation does not induce an amino acid(Phe) change according to the published human mitochondrial genetic code as well as the mtDNA sequence. Whether it affects the translation efficiency or transportation of signals between mitochondrial and nuclear genome needs further studies.

Adult↗

Congenital mitochondrial cytopathy and chronic progressive external ophthalmoplegia.

BACKGROUND: Chronic Progressive External Ophthalmoplegia (CPEO) encompasses different conditions having in common a slowly progressive external and general ophthalmoplegia. The discovery of CPEO is suggestive of mitochondrial cytopathy, but this is not necessarily so. CASE REPORT: We report here a case, presenting at age 9 months, characterized by bilateral blepharoptosis and partial third nerve oculomotor deficiency, with no nystagmus. Mitochondrial cytopathy was suspected on cranial MRI and confirmed by muscle biopsy. Enzyme studies revealed a defect on the complex I respiratory chain. This case is unique in that the symptoms completely resolved under a Ketogen diet.

Blepharoptosis↗

Chronic progressive external ophthalmoplegia with NADH-CoQ reductase deficiency: report of a case.

A thirty-two year old female had chronic progressive external ophthalmoplegia (CPEO), exertional fatigue, dysarthria, dysphagia, and bilateral hearing impairment. Histochemical stains, obtained from the right vastus lateralis, showed ragged-red fibers and wide-spread abnormalities in the number, size, and the structure of mitochondria under electronomicroscopic examination. A biochemical analysis showed a low activity of NADH-cytochrome C reductase, NADH dehydrogenase and a normal activity of succinate cytochrome C reductase and cytochrome C oxidase. This data suggests a specific defect in the NADH dehydrogenase of complex I (NADH CoQ reductase). We believe that this is the first biochemically defined mitochondrial myopathy reported in Taiwan and provides additional evidence for the existence of biochemical heterogeneity in mitochondrial disorders of CPEO.

Adult↗

[Familiar chronic progressive external ophthalmoplegia of mitochondrial origin].

INTRODUCTION: The syndrome of chronic progressive external ophthalmoplegia (CPEO) is a mitochondrial disease characterized by ptosis and ophthalmoplegia has that has been associated to the presence of large deletion, single or multiple, in the mitochondrial DNA of skeletal muscle. CASE REPORT: We report a familiar case of chronic progressive external ophthalmoplegia of maternal inheritance that began at birth, and developed with slow progression but with no multisystemic involvement. Non of the affected individuals had ragged-red fibers in skeletal muscle. Genetic analysis of mitochondrial DNA revealed the presence of a single deletion of 4,977 bp that encompasses the nucleotide positions 8,482 to 13,460, flanked by a direct repeat sequence. CONCLUSIONS: The amount of deleted mitochondrial DNA (15%) in this patient's muscle suggests, even if the percentage of the mutation is low, that this deletion is the molecular cause of the phenotypic presentation of this patient. This is one of the few cases described in the literature of CPEO maternally inherited.

Adolescent↗

[Vascular pathology in chronic progressive external ophthalmoplegia with ragged-red fibers].

Vascular involvement in biopsied muscle specimens from 11 patients with chronic progressive external ophthalmoplegia (CPEO) with ragged-red fibers (RRF) was studied. Almost none of 69 intramuscular arteries examined were strongly stained with succinate dehydrogenase (SDH) except one patient who had 2 SSV (strongly SDH-reactive blood vessels) in his muscle biopsy. Although RRF and focal cytochrome c oxidase (CCO) deficiency in muscle fibers were the common histochemical changes in muscle biopsy specimens from CPEO patients, all mitochondria in both endothelial and smooth muscle cells of the arteries had normal morphology except for the two SSV and all mitochondria in the blood vessels had normal CCO activity by electron cytochemistry. The findings obtained from the present study were quite different from those in mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), and myoclonus epilepsy associated with ragged-red fibers (MERRF) in which the striking vascular involvement with SSV is the most common and major abnormality in muscle biopsy specimens. To study vascular involvement in mitochondrial encephalomyopathies is the one of very important clues to understand the pathophysiology of phenotypic expressions in mitochondrial encephalomyopathies.

Adolescent↗

[Mitochondrial dysfunction in bipolar disorder].

Phosphorus magnetic resonance spectroscopic studies in bipolar disorder revealed altered brain energy metabolism resembling that of chronic progressive external ophthalmoplegia (CPEO). Mood disorder is one characteristic symptom in several families of CPEO caused by mutations of three genes, ANT1, Twinkle, and POLG. Molecular genetic analysis revealed association of bipolar disorder with mitochondrial DNA (mtDNA) 10398A polymorphism, 3644C mutation, and FDUFV2. In the postmortem brains, increased levels of mtDNA 4977bp deletion and 3243G mutation, and altered expression of mitochondria-related genes were reported. Mitochondria play an important role in neuroplasticity and apoptotic signaling via regulating intracellular calcium homeostasis. Thus, mitochondrial dysfunction may cause altered calcium homeostasis and neuroplasticity, resulting in bipolar disorder. Most molecular genetic findings in bipolar disorder regarding mitochondria and endoplasmic reticulum stress signaling are common to Parkinson's disease and diabetes mellitus. Thus, it is possible that bipolar disorder is also a disease caused by the progressive loss of some neuronal cells.

Bipolar Disorder↗

[Chronic progressive external ophthalmoplegia: clinical and electromyographic manifestations in a series of cases].

INTRODUCTION: Chronic progressive external ophthalmoplegia (CPEO) is a common mitochondrial disease. The different conditions in this group of diseases overlap clinically, enzymatically and genetically. There is no effective treatment. Ptosis improves with corrective surgery involving tarsorrhaphy as a palliative measure. CASE REPORTS: Code numbers were examined in a retrospective study conducted in order to search for patients with ptosis or ophthalmoplegia who had either visited or been admitted to the neurology department over the last 10 years. Data concerning these patients' clinical features and results of complementary tests were collected. Six patients with CPEO were identified, five of whom were females. Ages ranged from 44 to 72 years. All the patients had ptosis, although 50% were asymmetric. Half of them reported mild dysphagia while swallowing liquids. Levels of creatine phosphokinase and acetylcholine antireceptor antibodies were normal. Half the patients showed increased jitter and a muscle biopsy revealed that five of them had ragged red fibres. The most frequent enzyme deficit was complex I and IV deficiency. There were no familial forms; the most common genetic anomaly was single deletion in the mitochondrial deoxyribonucleic acid. CONCLUSIONS: In cases of ptosis and ophthalmoplegia that do not respond to anticholinesterases, knowledge of this condition makes it possible to avoid the use of immunosuppressant drugs, which have important side effects.

Adult↗

Mitochondrial disorder, diabetes mellitus, and findings in three muscles, including the heart.

The authors describe the case of a 50-year-old man with chronic progressive external ophthalmoplegia (CPEO), diabetes mellitus (DM), and coronary artery disease. The patient had no cardiac conduction abnormalities. During coronary artery bypass surgery, his heart and two skeletal muscles were biopsied. All three muscles showed ragged red fibers. The heart muscle showed significant glycogen accumulation. Analysis of mitochondrial DNA (mtDNA) showed a 5019-base-pair deletion, with no duplications. There were morphologically abnormal mitochondria in all 3 muscles, with clinically apparent difference in preservation of function. The combination of diabetes mellitus and mtDNA deletion is fortuitous, as they can be causally linked. The cardiac pathology allows speculation about the possible adaptive processes that may occur in the heart in DM. There are few reported cases with CPEO and excess glycogen in the heart. Most show deposition of fat and poorer clinical outcomes as compared to those with glycogen deposition. This observation may lend support to the hypothesis that in the myocardium, adaptive responses are mediated via changes in glucose handling, whereas alterations in fat metabolism likely represent maladaptation.

Biopsy↗

[Indications for pacemaker therapy in ophthalmoplegia plus and Kearns-Sayre syndrome].

Mitochondrial myopathies can affect the skeletal muscle, the central or peripheral nervous system, and they may be associated with chronic progressive external ophthalmoplegia (CPEO). In 7/29 patients with mitochondrial myopathies and CPEO a cardiac involvement (Kearns-Sayre syndrome) was found: incomplete right bundle branch block (n = 1), right bundle branch block (n = 1), left anterior fascicular block and right bundle branch block (n = 2), complete atrioventricular block (n = 3); congestive cardiac failure (ejection fraction 40%) (n = 2); 3/10 patients had prolonged infranodal conduction on His-bundle electrography (HV-interval 60 ms). The cardiac involvement in ophthalmoplegia plus is characterized by progressive impairment of fascicular conduction. The need for prophylactic pacemaker implantation appears to exist in patients with bifascicular block and prolonged His-ventricle conduction.

Adolescent↗

[A mitochondrial DNA mutation in the heteroplasmic tRNA-Tyr gene associated with chronic progressive external ophthalmoplegia--clinical and molecular biological study].

Determination of the total mtDNA sequence of a 42 year-old female with chronic progressive external ophthalmoplegia (CPEO) revealed a heteroplasmic G-to-A transition at nt. 5877 in the tRNA-Tyr gene and a homoplasmic T-to-C transition in the tRNA-Gln gene at 4343. The former mutation was located in a highly conserved nucleotide in the DHU loop. This mutation by restriction enzyme analysis using Ddel was observed only in the blood of her two asymptomatic children and her mother. The tRNA-Gln mutation in the T psi C loop was found in a few controls and in all of her maternal relatives. The cybrid clones including tRNA-Tyr mutation showed decreased oxygen utilization and fragility against oxygen stress. This tRNA-Tyr mutation is tightly associated with CPEO.

Adult↗

Dysfunction of the hypothalamic-pituitary system in mitochondrial encephalomyopathies.

We investigated endocrine function in patients with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS), myoclonus epilepsy associated with ragged-red fibers (MERRF), and chronic progressive external ophthalmoplegia (CPEO). Hypothalamic-pituitary function was impaired in all three patients with MELAS or MERRF, but none of four with CPEO. A MELAS patient with dwarfism and impaired adolescent development had decreased growth hormone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH). A MERRF patient had emaciation and low adrenocorticotropin. A patient with mitochondrial encephalomyopathy transitional between MELAS and MERRF showed delayed, blunted LH and FSH response to LH-releasing hormone stimulation. We concluded that patients with mitochondrial encephalomyopathies, especially MELAS or MERRF, are likely to have hypothalamic-pituitary dysfunction.

Adult↗

[A case of chronic progressive external ophthalmoplegia presenting as inflammatory myopathy].

A 64-year-old female had slowly progressive bilateral external ophthalmoplegia, blepharoptosis and muscle weakness of the extremities since age 30. Laboratory examination showed an elevation of serum CK level. Biopsied specimens from the left biceps and the left orbicularis oculi muscles revealed myopathic change with infiltration of mononuclear cells. In addition, some ragged-red fibers and a few cytochrome c oxidase-negative fibers, which are characteristic of mitochondrial myopathy, were observed. Polymerase chain reaction analysis of mtDNA in the muscles showed multiple mtDNA deletions. On administration of prednisolone (initial dose, 60 mg/day), blepharoptosis and muscular strength improved transiently and serum CK level was normalized but external ophthalmoplegia was not improved. We diagnosed our case as chronic progressive external ophthalmoplegia (CPEO). This is the first report of CPEO presenting as inflammatory myopathy.

DNA, Mitochondrial↗

Mitochondrial disorders: genetics, counseling, prenatal diagnosis and reproductive options.

Most patients with mitochondrial disorders are diagnosed by finding a respiratory chain enzyme defect or a mutation in the mitochondrial DNA (mtDNA). The provision of accurate genetic counseling and reproductive options to these families is complicated by the unique genetic features of mtDNA that distinguish it from Mendelian genetics. These include maternal inheritance, heteroplasmy, the threshold effect, the mitochondrial bottleneck, tissue variation, and selection. Although we still have much to learn about mtDNA genetics, it is now possible to provide useful guidance to families with an mtDNA mutation or a respiratory chain enzyme defect. We describe a range of current reproductive options that may be considered for prevention of transmission of mtDNA mutations, including the use of donor oocytes, prenatal diagnosis (by chorionic villus sampling or amniocentesis), and preimplantation genetic diagnosis, plus possible future options such as nuclear transfer and cytoplasmic transfer. For common mtDNA mutations associated with mitochondrial cytopathies (such as NARP, Leigh Disease, MELAS, MERRF, Leber's Hereditary Optic Neuropathy, CPEO, Kearns-Sayre syndrome, and Pearson syndrome), we summarize the available data on recurrence risk and discuss the relative advantages and disadvantages of reproductive options.

DNA, Mitochondrial↗

Overexpressions of myoglobin and antioxidant enzymes in ragged-red fibers of skeletal muscle from patients with mitochondrial encephalomyopathy.

To determine the relationship between myoglobin (Mb) and the defense system against reactive oxygen species in various myopathies, we performed immunohistochemical analyses of Mb and various antioxidant enzymes, including manganese superoxide dismutase (Mn-SOD), copper zinc SOD (CuZn-SOD), catalase (CAT), and glutathione peroxidase (GSH-Px). Biopsied muscle specimens were obtained from patients with chronic progressive external ophthalmoplegia (CPEO), Kearns-Sayre syndrome (KSS), Duchenne muscular dystrophy (DMD), and polymyositis (PM). In patients with CPEO/KSS, stainings of Mb, SOD, CAT, and GSH-Px in nonatrophic ragged-red fibers (RRFs) were more intense than those in non-RRFs. These pronounced stainings corresponded to ragged-red lesions. The staining intensities of these antioxidant enzymes were significantly correlated with that of Mb (P < 0.001). Atrophic RRFs in specimens from patients with CPEO/KSS showed intense stainings of these antioxidant enzymes but not intense staining of Mb. In specimens from patients with DMD/PM, the antioxidant enzymes but not Mb were overexpressed in degenerative fibers. These results suggest that oxidative stress is associated with Mb expression specifically in mitochondrial diseases. The antioxidant enzymes seem to be upregulated to protect against muscle damage in nonatrophic RRFs. However, the Mb-mediated oxidative damage may become more extensive and result in further mitochondrial dysfunction and progressive atrophy of RRF with impaired upregulation of Mb.

Adult↗