Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027066 (myoclonus)
 4,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report myoclonic epilepsy with ragged-red fibers (MERRF) syndrome in a Chinese family with confirmed mitochondrial DNA point mutation. Six members of the family including the grandmother, two siblings, and three grandchildren were affected. Among them, action myoclonus was seen in five; short stature, muscle weakness, and mental retardation in four; lactic acidosis, hearing impairment, and ataxia in two; and seizures in one. Muscle biopsy from two affected siblings revealed ragged-red fibers and abundant subsarcolemmal mitochondria with paracrystalline inclusions. Pedigree analysis suggests a maternal transmission. Analysis of mitochondrial DNA showed a point mutation from A to G at the 8344th nucleotide position located in the tRNA(Lys) gene. To our knowledge, this is the first report of MERRF syndrome with such genetic defect from a Chinese family. The present and previous reports support the notion that mitochondrial DNA point mutation at the 8344th nucleotide position is the most common cause of MERRF syndrome.
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PMID:Myoclonic epilepsy with ragged-red fibers (MERRF) syndrome: report of a Chinese family with mitochondrial DNA point mutation in tRNA(Lys) gene. 793 36

We describe a 42-year-old woman with overlapping syndrome of MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) and MERRF (myoclonus epilepsy and ragged-red fibers). Clinically, she had episodic headache, stroke-like episode with left hemiparesis and lactic acidosis commonly found in MELAS syndrome. However, myoclonus seizure, and ataxia with dyssynergic gait characteristic of MERRF were also noted. Computed tomographic scans showed a right temporo-parietal hypodense lesion. The lesion disappeared 20 months later, even magnetic resonance images also failed to reveal this abnormality. A molecular analysis of mitochondrial DNA was conducted by using restriction endonucleases ApaI and NaeI. A transition from A to G was found at the nucleotide position 3243, but not found at the 8344th nucleotide pair. In this report, we document the fluctuating CT changes and emphasize the importance of molecular analysis in patients with overlapping syndrome of mitochondrial encephalomyopathies.
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PMID:Overlapping syndrome of MERRF and MELAS: molecular and neuroradiological studies. 835 81

Recent advances in molecular genetics have led to a better understanding of mitochondrially inherited diseases. Mitochondrial encephalomyopathy overlap syndrome is one such group of diseases in which ocular abnormalities are frequently manifest. The authors describe the clinical, molecular genetic, and pathologic findings of two patients with the mitochondrial encephalomyopathy overlap syndrome. The patients shared a similar clinical course with features overlapping the three traditionally distinct clinical phenotypes (the Kearns-Sayre syndrome; the syndrome of mitochondrial encephalopathy, lactic acidosis, and stroke [MELAS], and the syndrome of myoclonus, epilepsy, and ragged red fibers [MERRF]). The patients had identical mitochondrial DNA mutations (at nucleotide position 3243) and had similar ultrastructural abnormalities, including abundant enlarged mitochondria with "whorled" and "tubular" cristae. These abnormal mitochondria appeared to be preferentially distributed in cells with high metabolic activity (retinal pigment epithelium, corneal endothelium, and extraocular muscles).
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PMID:Ocular clinicopathologic study of the mitochondrial encephalomyopathy overlap syndromes. 836 69

A rare point mutation at nucleotide position 8356 in the transfer RNA gene in mitochondrial DNA was found in a Japanese family. Our proband had migraine and dementia associated with lactic acidosis in addition to myoclonic epilepsy with ataxia and ragged-red fibres in a muscle biopsy specimen consistent with the clinical characteristics of myoclonic epilepsy with ragged-red fibres (MERRF). His mother, who had the same point mutation, also had migraine but without myoclonus or ataxia. His aunt, who had the same point mutation and migraine, developed diabetes mellitus, encephalomyopathy and several stroke-like episodes associated with lactic acidosis (MELAS). This is the third family with the rare mutation seen in American and Italian families. The mutation may not be specific to Caucasians, and is probably closely related to the MERRF/MELAS overlap syndrome.
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PMID:The T-C(8356) mitochondrial DNA mutation in a Japanese family. 880 15

We report a 6-month-old girl with episodic hyperventilation, myoclonus, disturbed consciousness, and lactic acidosis. Brain sonogram revealed progressive ventriculomegaly, and MRI showed symmetric low densities over the putamen bilaterally with diffuse cortical cystic lesions. Ragged-red fibers were noted in the muscle biopsy. Molecular analysis revealed a heteroplasmic T-->G mutation at nucleotide position (np) 8993 of mitochondrial DNA (mtDNA). The proportion of the mutant mtDNA in the muscle of the proband was estimated to be 86%. Her mother and maternal uncle also harbored the same mutant mtDNA (54 and 48% in their leukocytes, respectively). One of her sisters carried 64% mutant mtDNA in her leukocytes, but another sister did not. These results suggest that this mutant mtDNA is transmitted through the maternal lineage in this family in a randomly segregated manner. To our knowledge, this is the first report of a Chinese patient with Leigh syndrome associated with the T-->G substitution at np 8993 of mtDNA.
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PMID:Leigh syndrome associated with mitochondrial DNA 8993 T-->G mutation and ragged-red fibers. 885 7

We report three members of a family, who exhibited a phenotype similar to 'myoclonus epilepsy with ragged-red fibers' but had a genotype usually associated with 'mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes'. The patients, a 48-year-old female, and her two sons, aged 21 and 19 respectively, presented with photo-reactive syncopal episodes, disturbances of gait and writing, dysarthria and finger tremor since the 3rd and 2nd decade of life, respectively, that were accompanied also by numbness and weakness of the extremities. Subsequently, cerebellar ataxia and myoclonus were also noted. Electromyography revealed both myogenic and neurogenic muscular changes, and nerve conduction studies demonstrated a sensory-motor neuropathy. Biopsy showed ragged-red fibers with strongly stained SDH-positive vessels in skeletal muscles, and a marked loss of myelinated fibers of the sural nerves. Mitochondrial (mt) DNA analyses of peripheral blood, muscles and nerves revealed that all members had a heteroplasmic np3271 (T-C) point mutation in the mitochondrial tRNA-Leu gene (UUR). This family is unique, in that all patients presented with a myoclonus epilepsy with ragged-red fibers-like phenotype and had a distinctive peripheral neuropathy, while the detected mtDNA 327l (T-C) mutation has been reported to date only in rare cases of mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes
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PMID:A mitochondrial encephalo-myo-neuropathy with a nucleotide position 3271 (T-C) point mutation in the mitochondrial DNA. 1140 19

Congenital disorders of glycosylation (CDG) and mitochondrial diseases are multisystem disorders with clinical characteristics that may overlap. We present four patients with CDG whose phenotypes suggested the diagnosis of a mitochondrial disease. Patients 1 and 2 are siblings with hemiplegic headache, stroke-like episodes, lactic acidaemia and history of maternal migraine; their initial clinical diagnosis was MELAS syndrome (mitochondrial encephalopathy, lactic acidosis and stroke-like episodes). Patient 3 suffers from ataxia, neuropathy, ophtalmoplegia and retinitis pigmentosa suggestive of NARP (neuropathy, ataxia, and retinitis pigmentosa) syndrome. Patient 4 presented with neurological regression mimicking Leigh disease, with ptosis, myoclonus, ataxia and brainstem and cerebellar atrophy. Screening for mitochondrial disease including enzyme and mtDNA investigations on muscle biopsy were performed on Patients 1, 2 and 4 with normal results. However, evidence for a glycosylation disorder was substantiated by an increased carbohydrate deficient transferrin (CDT). The isoelectric focussing pattern of serum sialotransferrin was typical of CDG type I in Patients 1, 2 and 3 and was shifted towards the less sialylated bands in case 4. A deficiency of phosphomanomutase (PMM) confirmed the diagnosis of CDG-Ia in Patients 1, 2 and 3, who are compound heterozygous for mutations R141H/T237M (Patients 1 and 2) and R141H/P113L (Patient 3). In Patient 4, PMM activity was normal, and further enzymatic and molecular studies are underway. As the search for the primary defect in mitochondrial diseases is often unsuccessful, the pool of mitochondrial patients that remain without definite diagnosis might include CDG cases. Routine screening for CDG may avoid precocious invasive investigations.
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PMID:Congenital disorders of glycosylation (CDG) may be underdiagnosed when mimicking mitochondrial disease. 1158 67

Mitochondrial encephalopathies are a group of diseases that have as their pathogenic basis an alteration of the mitochondrial DNA (mtDNA). The MELAS phenotype (mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes) has been related to mutation A3243G in approximately 80% of the cases reported. MERRF (epilepsy myoclonus with ragged red fibers) has been related to mutation A8344G and A8566G of tRNA Lys. We report the case of a 7 months-old female with early clinical signs of encephalopathy associated to the A3243G mutation. Laboratory tests showed lactic acidosis and the EEG pattern was compatible with an encephalopathic process. The infant was treated with ACTH during one month, with clinical and electroencephalographic improvements. Currently, she is receiving treatment with B-vitamins, L-Carnitine and urinary alkalizing agents. It is concluded that an analysis of mtDNA must be made in infants who present convulsions, delay in their psychomotor development, lactic acidosis and an EEG pattern compatible with an encephalopathy, to rule out a mitochondrial disease.
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PMID:[Infantile encephalopathy associated with the MELAS A3243G mutation. Case report]. 1759 46

Mitochondrial respiratory chain disorders are relatively common inborn errors of energy metabolism, with a combined prevalence of one in 5000. These disorders typically affect tissues with high energy requirements, and cerebral involvement occurs frequently in childhood, often manifesting in seizures. Mitochondrial diseases are genetically heterogeneous; to date, mutations have been reported in all 37 mitochondrially encoded genes and more than 80 nuclear genes. The major genetic causes of mitochondrial epilepsy are mitochondrial DNA mutations (including those typically associated with the mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes [MELAS] and myoclonic epilepsy with ragged red fibres [MERRF] syndromes); mutations in POLG (classically associated with Alpers syndrome but also presenting as the mitochondrial recessive ataxia syndrome [MIRAS], spinocerebellar ataxia with epilepsy [SCAE], and myoclonus, epilepsy, myopathy, sensory ataxia [MEMSA] syndromes in older individuals) and other disorders of mitochondrial DNA maintenance; complex I deficiency; disorders of coenzyme Q(10) biosynthesis; and disorders of mitochondrial translation such as RARS2 mutations. It is not clear why some genetic defects, but not others, are particularly associated with seizures. Epilepsy may be the presenting feature of mitochondrial disease but is often part of a multisystem clinical presentation. Mitochondrial epilepsy may be very difficult to manage, and is often a poor prognostic feature. At present there are no curative treatments for mitochondrial disease. Individuals with mitochondrial epilepsy are frequently prescribed multiple anticonvulsants, and the role of vitamins and other nutritional supplements and the ketogenic diet remain unproven.
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PMID:Mitochondrial disease and epilepsy. 2228 95

We report the case of a 19-year-old Chinese female harboring the m.3291T>C mutation in the MT-TL1 gene encoding the mitochondrial transfer RNA for leucine. She presented with a complex phenotype characterized by progressive cerebellar ataxia, frequent myoclonus seizures, recurrent stroke-like episodes, migraine-like headaches with nausea and vomiting, and elevated resting lactate blood level. It is known that the myoclonus epilepsy with ragged-red fibers (MERRF) is characterized by cerebellar ataxia and myoclonus epilepsy, while that the mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is characterized by recurrent stroke-like episodes, migraine-like headaches, and elevated resting lactate blood level. So the patient's clinical manifestations suggest the presence of a MERRF/MELAS overlap syndrome. Muscle biopsy of the patient showed the presence of numerous scattered ragged-red fibers, some cytochrome c oxidase-deficient fibers, and several strongly succinate dehygrogenase-reactive vessels, suggestive of a mitochondrial disorder. Direct sequencing of the complete mitochondrial genome of the proband revealed no mutations other than the T-to-C transition at nucleotide position 3291. Restriction fragment length polymorphism analysis of the proband and her family revealed maternal inheritance of the mutation in a heteroplasmic manner. The analysis of aerobic respiration and glycolysis demonstrated that the fibroblasts from the patient had mitochondrial dysfunction. Our results suggest that the m.3291T>C is pathogenic. This study is the first to describe the m.3291T>C mutation in association with the MERRF/MELAS overlap syndrome.
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PMID:MERRF/MELAS overlap syndrome due to the m.3291T>C mutation. 2433 29


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