Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0013362 (dysarthria)
 3,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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

We report a 23-year-old man with mitochondrial encephalomyopathy. At 21 years of age, he noted speech distubance. Since his dysarthria did not improve thereafter, he was admitted to our hospital. On admission, he showed mild gynecomastia. Neurological examination revealed mild decrease in performance IQ in WAIS-R, mild scanning speech, mild left hearing disturbance, mild to moderate muscle weakness in proximal four extremities, mild bilateral limb ataxia, and mild to moderate truncal ataxia. While, no brisk deep tendon reflex, pathological reflex, aberrant muscle tonus, sensory disturbance, retinopathy, myoclonus or autonomic disorder was found. Serum levels of lactate (23.2 mg/dl, normal<18.7) and pyruvate (1.23 mg/dl, normal<0.94) were elevated, and serum lactate levels were markedly elevated (118.1 mg/dl) after 15-minute exercise (15 Watts/minute). CSF levels of lactate (31.2 mg/dl, normal<12.5) and pyruvate (1.48 mg/dl, normal<0.75) were also elevated. Head MRI showed mild cerebral and cerebellar atrophy, but 1H-MRS showed no lactate peak. Moreover, muscle biopsy from left biceps muscle showed lots of ragged-red fibers, and he was thus diagnosed as having mitochondrial encephalomyopathy. However, nt3243 mutation of mitochondria DNA was not present. Next, we confirmed gynecomastia by mammography, and checked serum levels of estrogens. Mildly decreased estradiol (19.9 pg/ml, normal, 20-59), normal estrone (24.0 pg/ml, normal<30.0) and mildly increased estriol (6.03 pg/ml, normal<5.0) were found. While, the serum levels of cortisol, dehydroepiandrosterone-sulfate (DHEA-S), androstenedione, testosterone, luteinizing hormone (LH) and follicle stimulating hormone (FSH) were all within normal limits. Since the steroid hormone synthesis system and hypothalamus-pituitary system seem to be normal, 16alpha-hydroxylase that converts estradiol to estriol may be upregulated. While, aromatase (P-450arom) is well known to convert androgens to estrogens. In addition, 16alpha-hydroxylase and P-450arom convert DHEA-S to estriol. Since it is recently reported that P-450arom is considerably expressed in muscle tissues as well as fat tissues and that muscle tissue may be a major organ to produce estrogens in men and postmenopausal women, estriol production may be increased in the present patient's muscle. Although hypogonadism due to hypothalamus-pituitary disorders was sometimes reported, there have been no reports that suggest an increased estrogen production in skeletal muscles in mitochondrial encephalomyopathies. Recently, estrogen has been known to protect muscle fibers from oxidative damages due to exercise. Thus, it is of potential that estrogens increased locally in muscle tissues of the patients with mitochondrial encephalomyopathies protect muscle fibers from oxidative damage due to mitochondrial dysfunction.
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PMID:[A patient with mitochondrial encephalomyopathy presenting gynecomastia with elevation of serum estriol level]. 1528 12

Mutations in the nuclear gene POLG (encoding the catalytic subunit of DNA polymerase gamma) are an important cause of mitochondrial disease. The most common POLG mutation, A467T, appears to exhibit considerable phenotypic heterogeneity. The mechanism by which this single genetic defect results in such clinical diversity remains unclear. In this study we evaluate the clinical, neuropathological and mitochondrial genetic features of four unrelated patients with homozygous A467T mutations. One patient presented with the severe and lethal Alpers-Huttenlocher syndrome, which was confirmed on neuropathology, and was found to have a depletion of mitochondrial DNA (mtDNA). Of the remaining three patients, one presented with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS), one with a phenotype in the Myoclonic Epilepsy, Myopathy and Sensory Ataxia (MEMSA) spectrum and one with Sensory Ataxic Neuropathy, Dysarthria and Ophthalmoplegia (SANDO). All three had secondary accumulation of multiple mtDNA deletions. Complete sequence analysis of muscle mtDNA using the MitoChip resequencing chip in all four cases demonstrated significant variation in mtDNA, including a pathogenic MT-ND5 mutation in one patient. These data highlight the variable and overlapping clinical and neuropathological phenotypes and downstream molecular defects caused by the A467T mutation, which may result from factors such as the mtDNA genetic background, nuclear genetic modifiers and environmental stressors.
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PMID:A Clinical, Neuropathological and Genetic Study of Homozygous A467T POLG-Related Mitochondrial Disease. 2673 72

Mitochondrial diseases (MIDs) are a large group of heterogeneous disorders due to mutations in either mitochondrial DNA (mtDNA) or nuclear DNA (nDNA) genes, the latter encoding proteins involved in mitochondrial function. A multisystem clinical picture that involves several organs, including both the peripheral and central nervous systems, is a common presentation of MID. Movement disorders, even isolated ones, are not rare. Cerebellar ataxia is common in myoclonic epilepsy with ragged red fibers (MERFF) due to mutations in the mitochondrial transfer RNA (tRNA) lysine gene, in Kearns-Sayre syndrome due to mtDNA deletions, in sensory ataxic neuropathy with dysarthria and ophthalmoplegia (SANDO) due to nuclear POLG1 gene mutations, and also in ARCA2, Friedreich's ataxia, SPG7, SCA28 and autosomal-recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) due to mutations in nuclear genes involved in mitochondrial morphology or function. Myoclonus is a key feature of MERFF, but may also be encountered in mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS), ARCA2, POLG1 mutations and Leigh syndrome. Dystonia is common in Leigh syndrome (which may be caused by 75 different genes) and in Leber hereditary ocular neuropathy (LHON) plus disease, due to mutations in mtDNA genes that encode subunits of NADH dehydrogenase, as well as in ARCA2, pantothenate kinase-associated neurodegeneration (PKAN), mitochondrial membrane protein-associated neurodegeneration (MPAN) and POLG1 mutations. Other movement disorders are rarer (such as parkinsonism, tremor, chorea). Although parkinsonism is more frequent in POLG1 mutations, and myoclonus in MERFF, most movement disorders are found either isolated or combined in numerous MIDs. The presence of associated neurological signs, whether central or peripheral, or of evocative magnetic resonance imaging (MRI) abnormalities (striatal necrosis) should prompt a search for MID. In cases of a particular clinical spectrum (LHON, MERFF, Kearns-Sayre, SANDO, SPG7, ARCA2, ARSACS), a search for the most frequently implicated mutation(s) is recommended. In other cases, muscle biopsies followed by metabolic and genetic studies may be useful for arriving at a diagnosis.
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PMID:Movement disorders in mitochondrial diseases. 2777 46