Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004134 (ataxia)
 15,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Several members of a three-generation kindred from Sardinia were affected by a maternally inherited syndrome characterized by features of both myoclonus epilepsy with ragged-red fibers (MERRF) and mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS). Clinically, symptoms such as myoclonus epilepsy, neural deafness and ataxia were variably associated with stroke-like episodes and/or migrainous attacks. Morphologically, numerous MELAS-associated SDH-stained vessels were observed in muscle biopsies, either alone or in combination with ragged-red fibers, the morphological hallmark of MERRF. Sequence analysis of the mtDNA tRNA genes revealed the presence of a single, heteroplasmic T-->C transition at nt 8356, in the region of the tRNA(Lys) gene corresponding to the T-psi-C stem. The T-->C(8356) transition was exclusively found in the maternal lineage of our family, and the relative amount of the mutant mtDNA species in muscle was correlated with the severity of the clinical presentation. Therefore, we propose that the T-->C(8356) transition is responsible for the mitochondrial encephalomyopathy found in our family, and must be added to the expanding list of the pathogenetically relevant mutations of human mtDNA.
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PMID:A MERRF/MELAS overlap syndrome associated with a new point mutation in the mitochondrial DNA tRNA(Lys) gene. 806 54

This article reports a new MERRF family. The mother, regarded as suffering from Ramsay-Hunt Syndrome, and her three daughters, had the same clinical pattern: myoclonic epilepsy and ataxia. Two daughters were studied on morphological, biochemical and molecular genetic levels. Muscle biopsies showed ragged-red fibres and mitochondrial vasculopathy. Arterioles were strongly SDH-reactive and COX-negative. By electron microscopy, abnormal mitochondria were observed in skeletal muscle fibres, in smooth muscle fibres of intramuscular vessels and in sweat gland epithelium. The study of the respiratory chain showed complex IV and I + IV deficiency, respectively. Mitochondrial tRNA (lys) mutation at position 8344 was pointed out as previously reported in the MERRF syndrome.
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PMID:Merrf family with 8344 mutation in tRNA (lys). Evidence of a mitochondrial vasculopathy in muscle biopsies. 818 18

Two siblings (one man, one woman), presenting with diarrhea, severe weight loss peripheral neuropathy, ophthalmoparesis, asymptomatic leukoencephalopathy were diagnosed as a new cases of Mitochondrial Neuro Gastro Intestinal Encephalomyopathy syndrome (MNGIE). Hirano (1994) defined four criteria for the diagnostic: peripheral neuropathy, ophthalmoparesis, gastro intestinal dysmotility, muscle biopsy with histologic features of mitochondrial myopathy (ragged-red fibers, muscle fibers with increased succinate deshydrogenase stain or ultra structurally abnormal mitochondria). In a review of the literature, we found 31 cases with MNGIE. With our two cases, we study this group of 33 patients. First symptoms begin about 13.5 years with a median of 10 years and extremes for 1 to 32 years. The first signs are gastro intestinal symptoms (recurrent nausea, vomiting or diarrhea with intestinal dysmotility) in 22 cases, an ophthalmoparesia in 4 cases, intestinal and ocular signs in 1 case, gait ataxia or peripheral neuropathy in 3 cases, hearing loss in 1 case, gait ataxia or peripheral neuropathy in 3 cases, hearing loss in 1 case. During the evolution, besides the cardinal signs, the following features have been observed with a variable frequency: hearing loss, short stature, facial palsy, dysphonia, dysarthria, sweating, orthostatic hypotension, bladder dysfunction, hepatomegalia, The laboratory features are: abnormal Nerve Condition Studies/EMG compatible with a sensory motor neuropathy, lactic acidosis, mitochondrial respiratory chain defect (essentially complex IV deficiency, complex I deficiency or multiple complex defect), MRI leukodystrophy, elevated CSF protein, heart block, ragged-red fibers or increased SDH stain. The prognosis is poor, due to a severe weight loss bordering on cachexia 13 patients died with a mean age of 28.5 years (median 24 years, extreme 3 years to 51 years). The prognosis seems to be worsened by a young age of onset. The 33 patients belong to 19 families with 7 cases of consanguinity. 25 patients had a brother, a sister or a cousin affected. The study of these families is compatible with an autosomic recessive transmission, suggesting a pathology of the nuclear genomi, probably impliying the control of the mitochondrial DNA replication. In fact, in 13 cases, a study of the mt DNA was realized: multiple deletions were founded in 6 cases, multiples mutations in one case, unique mutation in 1 case. In 5 cases ther was no evidence of abnormality. These precise etiology and pathophysiologic significance of the mt DNA deletions, and the heterogeneity of the modifications of the mt DNA remain unknown. However, the possibility of various phenotypes for a same genotype or inversely is known in mitochondriopathies.
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PMID:[MNGIE syndrome in 2 siblings]. 968 18

The mitochondrial m-AAA protease has a crucial role in axonal development and maintenance. Human mitochondria possess two m-AAA protease isoenzymes: a hetero-oligomeric complex, composed of paraplegin and AFG3L2 (Afg3 like 2), and a homo-oligomeric AFG3L2 complex. Loss of function of paraplegin (encoded by the SPG7 gene) causes hereditary spastic paraplegia, a disease characterized by retrograde degeneration of cortical motor axons. Spg7(-/-) mice show a late-onset degeneration of long spinal and peripheral axons with accumulation of abnormal mitochondria. In contrast, Afg3l2(Emv66/Emv66) mutant mice, lacking the AFG3L2 protein, are affected by a severe neuromuscular phenotype, due to defects in motor axon development. The role of the homo-oligomeric m-AAA protease and the extent of cooperation and redundancy between the two isoenzymes in adult neurons are still unclear. Here we report an early-onset severe neurological phenotype in Spg7(-/-) Afg3l2(Emv66/+) mice, characterized by loss of balance, tremor and ataxia. Spg7(-/-) Afg3l2(Emv66/+) mice display acceleration and worsening of the axonopathy observed in paraplegin-deficient mice. In addition, they show prominent cerebellar degeneration with loss of Purkinje cells and parallel fibers, and reactive astrogliosis. Mitochondria from affected tissues are prone to lose mt-DNA and have unstable respiratory complexes. At late stages, neurons contain structural abnormal mitochondria defective in COX-SDH reaction. Our data demonstrate genetic interaction between the m-AAA isoenzymes and suggest that different neuronal populations have variable thresholds of susceptibility to reduced levels of the m-AAA protease. Moreover, they implicate impaired mitochondrial proteolysis as a novel pathway in cerebellar degeneration.
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PMID:Genetic interaction between the m-AAA protease isoenzymes reveals novel roles in cerebellar degeneration. 1928 3

Objective: To investigate the clinical features and imaging characteristics of mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS).Methods: Seventeen patients with MELAS diagnosed in the Affiliated Hospital of Xuzhou Medical University from July 2014 to August 2018 were enrolled in this study and their clinical manifestations, imaging and histopathological features were retrospectively analysed. We also discussed and summarised the related literature.Results: All of the 12 patients had seizures; stroke-like episodes in 12 cases; audio-visual impairment in 12 cases; headache in six cases; dysplasia in four cases; mental retardation in three cases; ataxia in two cases. On cranial magnetic resonance (MR) scans, the most common manifestations were in temporal-occipital-parietal lobe, cortical or subcortical areas as well as frontal lobe, thalamus, and basal ganglia showing long or equal T1 signals, long T2 signals, and hyperintense or iso-intense diffusion-weighted imaging (DWI) signals accompanied by ventricular enlargement and brain atrophy. MR spectroscopy showed that lactic acid peaks could be found in lesion sites, normal brain tissues, and cerebrospinal fluid. Muscle biopsy and genetic testing are the gold standard for diagnosing MELAS, muscle biopsy revealed COX-negative muscle fibres and SDH-stained red ragged fibres (RRF) under the sarcolemma. Mutations of mtDNA A3243G locus were common on gene testing. Improvement of mitochondrial function was observed after symptomatic and supportive treatment.Conclusion: MELAS should be considered for patients with epileptic seizures, headache, stroke-like episodes, extraocular palsy, cognitive decline and other clinical manifestations with the lesion located in the temporal-occipital-parietal lobe regardless of the distribution of blood vessels, and further examinations including muscle biopsy and gene testing should be performed to confirm the diagnosis.
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PMID:An analysis of the clinical and imaging features of mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS). 3200 May 57