Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0162671 (MELAS)
 587 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report a 9 year-old boy with MELAS. High dosed oral thiamine administration and high fat diet induced remarkable neurological and biochemical improvement. His mother had episodic headaches and hemiplegia, probably MELAS. He complained muscle weakness and repeated episodes of vomiting started from 2 years of age. High levels of serum lactate and pyruvate were recognized, but with no metabolic acidosis. He developed generalized muscle weakness, growth retardation, generalized convulsions and stroke-like episodes at 5 years old. Optic nerve atrophy and mental retardation gradually appeared. A muscle biopsy at 5 years old revealed numerous ragged-red fibers with excess accumulation of lipid droplets and glycogen particles. Scattered fibers had no cytochrome c oxidase (CCO) activity representing focal CCO deficiency. An electron microscopy showed markedly increased number of giant mitochondria filled with markedly proliferated complicated cristae. Pyruvate dehydrogenase complex level in the fibroblasts was within normal ranges. Serum carnitine level was normal. With oral administration of thiamine hydrochloride (1000 mg) and high fat diet (60-70%), muscle weakness improved, and lactate and pyruvate levels in the serum reduced to normal ranges, whereas the mental deterioration, muscle atrophy, pes cavus progressed very slowly. He died from cardiac and renal failures at 9 years old. Autopsied muscles showed a marked decrease in cytochrome c oxidase activity (biochemically 12.8% of the normal level), and almost all muscle fibers had no cytochrome c oxidase activity histochemically. The progression of the MELAS was probably in parallel with the decrease in CCO activity.
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PMID:[A case of MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) with progressive cytochrome c oxidase deficiency]. 255 13

A 12-year-old boy with corticosteroid-responsive mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) is described. His mother proved to have an asymptomatic mitochondrial myopathy on examination of a muscle biopsy specimen. Three weeks after the onset of vomiting, headache, ataxia and visual and speech impairment, he presented with a background of somatic growth retardation, deafness and school failure. Examination revealed disorientation, dysphasia, dyspraxia, optic atrophy, hemianopia, hemiparesis and sensory inattention. A cranial computed tomographic scan disclosed a large, low-density area, which was consistent with infarction, in the left posterior hemisphere and marked calcification of the basal ganglia bilaterally. Within two weeks of the commencement of corticosteroid treatment, the neurological dysfunction resolved. Attempts to decrease the dosage of dexamethasone caused an exacerbation of symptoms repeatedly. Two weeks after ceasing corticosteroid therapy, the patient developed a serious neurological relapse and a new, large, low-density area, which resembled an infarction, in the right posterior hemisphere on a computed tomographic scan. The reintroduction of corticosteroid therapy again resulted in the rapid resolution of all symptoms. It became evident that the patient had an exquisitely sensitive corticosteroid dependency, whereby a reduction in the dexamethasone dosage of even 0.25 mg a day caused confusion, headaches and increasing lactic acidaemia. Although it is difficult to assess the impact of various therapies in MELAS because of the episodic natural course of the disease, this remarkable corticosteroid responsiveness also has been noted in four previously reported patients with MELAS syndrome; therefore, it would seem reasonable to suggest that corticosteroid therapy now should be considered as standard treatment for this condition. However, corticosteroid therapy in other forms of mitochondrial disorders still awaits careful evaluation.
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PMID:Mitochondrial encephalomyopathy with corticosteroid dependence. 273 98

A 4-year-old boy presented with developmental delay, aggressive behavior, and incoordination. His EEG showed a diffuse encephalopathy. At age 10 he developed convulsions and severe migraine-like headaches. Muscle wasting, arreflexia, and lactic acidemia following exercise were noted. Electromyography was myopathic and nerve conduction studies revealed a peripheral neuropathy. Muscle biopsy demonstrated variation in fiber size and an excess of lipid droplets. He than had several stroke-like episodes and periods of unconsciousness, associated with severe metabolic acidosis. Muscle cytochrome C oxidase was abnormally low. This boy displayed the classical clinical and biochemical features of MELAS syndrome, namely Mitochondrial myopathy, Encephalopathy, Lactic Acidosis, and Stroke-like episodes. Treatment included carnitine, vitamin C, vitamin K, riboflavin, coenzyme Q10, and corticosteroids. He died at the age of 14 years following an episode of seizures, coma, and gastrointestinal hemorrhage. This is the first reported case of MELAS syndrome in Israel.
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PMID:MELAS syndrome: peripheral neuropathy and cytochrome C-oxidase deficiency: a case report and review of the literature. 772 60

We describe a family which demonstrates and expands the extreme clinical variability now known to be associated with the A-->G transition at nucleotide position 3243 of the mitochondrial DNA. The propositus presented at birth with clinical manifestations consistent with diabetic embryopathy including anal atresia, caudal dysgenesis, and multicystic dysplastic kidneys. His co-twin was normal at birth, but at 3 months of life, presented with intractable seizures later associated with developmental delay. The twins' mother developed diabetes mellitus type I at the age of 20 years and gastrointestinal problems at 22 years. Since age 19 years, the maternal aunt has had recurrent strokes, seizures, mental deterioration and deafness, later diagnosed as MELAS syndrome due to the tRNA(Leu(UUR)) A-->G mutation. A maternal uncle had diabetes mellitus type I, deafness, and normal intellect, and died at 35 years after recurrent strokes. This pedigree expands the known clinical phenotype associated with tRNA(Leu(UUR)) A-->G mutation and raises the possibility that, in some cases, diabetic embryopathy may be due to a mitochondrial cytopathy that affects both the mother's pancreas (and results in diabetes mellitus and the metabolic dysfunction associated with it) and the embryonic/fetal and placental tissues which make the embryo more vulnerable to this insult.
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PMID:The expanding clinical phenotype of the tRNA(Leu(UUR)) A-->G mutation at np 3243 of mitochondrial DNA: diabetic embryopathy associated with mitochondrial cytopathy. 872 72

A 25-year-old man developed nausea, vomiting, severe headache, and confusion. He had a past history of hyperuricemia and mild renal dysfunction. On admission he had somatic growth retardation, hypertrichosis, and bilateral auditory impairment. A cranial CT scan showed a small area of low density in the left temporal lobe and cerebellar atrophy. Five days later, he developed right homonymous hemianopia, sensory aphasia, and sensory inattention, and a new, large area of low density in the left occipital lobe on a cranial CT scan. On laboratory examination, lactate, pyruvate, and the lactate-to-pyruvate ratio were elevated in both the serum and cerebrospinal fluid. The biopsied muscle showed ragged red fibers and strongly SDH-reactive blood vessels. Gene analysis revealed the presence of the A 3243 G point mutation of the mitochondrial tRNA(Leu) gene in his blood leucocytes and muscle. Serum concentrations of BUN and creatinine were elevated to 46 mg/dl and 2.2 mg/dl, respectively. Creatinine clearance was 14.1 ml/min. An abdominal CT scan disclosed atrophy of his left kidney with subcapsular calcification and the findings of his abdominal ultrasonography were compatible with chronic renal failure. His mother, who suffered from renal failure and became dialysis dependent in her late forties also bore the A 3243 G mutation of the mitochondrial tRNA(Leu) gene in her circulating leucocytes. Though the association between MELAS and renal dysfunction still remains obscure, we speculate that renal failure can be a manifestation of MELAS.
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PMID:[Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) with chronic renal failure: report of mother-child cases]. 897 30

We report the clinical, pathological, and genetic findings of a case of MELAS syndrome. This was a man who died for metabolic failure at the age of 27 years. His familiar history was positive for hypoacusia and stroke. He was of short stature and presented mild mental retardation. Since the age of 21 he suffered from recurrent brain-ischemic lesions mainly in the occipital lobes, documented by repeated CT scans. The laboratory data and muscle biopsy disclosed lactic acidosis with ragged red fibres. Neurophysiological data and peripheral nerve biopsy showed an axonal neuropathy. A point mutation in the tRNALeu(UUR) gene of mitochondrial DNA was detected in 5 post-mortem tissues and in muscle biopsy. No defects of mitochondrial respiratory chain were detected. The histological and ultrastructural studies of the brain showed multiple and heterogeneous ischemic lesions with no obvious alterations of cerebral blood vessels. These lesions do not correspond to the vascular territories of main cerebral arteries. Our observations support the hypothesis that local metabolic alterations would play a crucial role in the pathogenesis of cerebral ischemic lesions in MELAS. The correlation between genetic, biochemical, and pathological data are discussed.
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PMID:Mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS). 926 44

The male proband reported here was born with appropriate anthropometric parameters at term as the second child of healthy nonconsanguineous parents. His only clinical symptom was bilateral congenital cataracts with strabismus at birth, and both lenses were removed surgically at the age of 8 months. The perinatal and infantile period thereafter was clinically uneventful and his psychomotor development appeared almost normal. At the age of 6 years he was hospitalized for slight muscle weakness, minor ptosis, nystagmus and decreased physical activity. Soon after, his general condition worsened, gait ataxia presented, dysphagia and difficulty of speech followed by rapidly progressive generalized ataxia, and myopathy developed. Typical progressive gray matter degeneration with focal necrosis in the basal ganglia characteristic of the Leigh type of neuropathology could be detected by cranial MRI, the muscle histology showed ragged-red fibers. At the age of 7.5 years, unexpected left side hemiparesis with speech disability resembling that seen in MELAS syndrome developed, from which he recovered within 1.5 days. The mtDNA of the patient showed single 6.7 kb large-scale deletion harboring between 7817 and 14 536 bp. This case represents the first report of a verified mtDNA mutation associated with congenital cataracts as the first clinical sign of a later developing progressive neuromuscular disease presented with a combination of Leigh neuropathology, ragged-red fiber histopathology and stroke-like attack.
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PMID:Congenital cataract as the first symptom of a neuromuscular disease caused by a novel single large-scale mitochondrial DNA deletion. 1273 42

The syndrome of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episode (MELAS) is typically associated with a single point mutation in the mitochondrial genome (mtDNA). Because mtDNA is known to have a higher mutation rate than nuclear DNA, we speculate that some patients with MELAS syndrome may harbor more than one mutation in mtDNA. For this purpose, mtDNA extracted from muscle containing dysmorphic mitochondria from a 32-year-old man with MELAS was sequenced in its entirety to identify all possible mutations. The result showed a homoplasmic A14693G and a heteroplasmic A3243G. The A14693G transition was not present in 205 unrelated control individuals, was not seen in 76 species randomly selected from GenBank, and appears to disrupt the base pairing within the T-loop of mtDNA tRNA(Glu). His asymptomatic siblings' blood showed wild-type at these positions, whereas the blood of the patient's oligosymptomatic diabetic mother had a heteroplasmic A14693G and an apparent homoplasmic wild-type A3243, suggesting an association of A14693G with diabetes mellitus. This case demonstrates the importance of sequencing the mtDNA in its entirety to evaluate the molecular basis of mitochondriopathy.
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PMID:Melas with point mutations involving tRNALeu (A3243G) and tRNAGlu(A14693g). 1457 59

A 30-year-old man was hospitalized with dysarthria and weakness of his right arm and leg. Three months previously, he had noticed numbness and weakness of his right shoulder, which spread to involve his left leg but which improved after 8 months. On admission, neurological examination revealed limb kinetic apraxia and constructive apraxia of the right hand, motor aphasia, dysarthria, and spastic quadriplegia. Sensory examination revealed hyperalgesia and dysesthesia in the right arm and left leg. Deep tendon reflexes were hyperactive in all four extremities. And he had bilateral Babinski signs. Laboratory examination revealed pH 7.38, PCO2 46.1 Torr, PO2 93.4 Torr, BE 1.7, and blood lactate, 9.0 mg/dl (normal 5-20 mg/dl). Cerebrospinal fluid lactate level was 20.0 mg/dl. pyruvate 1.34 mg/dl. and protein 83 mg/dl. Blood lactate and pyruvate values were markedly elevated after aerobic exercise. T2WI brain MRI showed scattered high signal lesions in the left precentral and postcentral gyrus, right paracentral lobes, both superior frontal gyri, and right superior temporal gyrus. Right biceps brachi biopsy showed almost complete cytochrome c oxidase (COX) deficiency. There were no ragged-red fibers. There was marked decrease of COX activity: 2.7 nmol/min/mg-mitochondrial protein (normal range: 33.0 +/- 16.1, n = 7) in the biopsied muscle. Open brain biopsy (after permission from the patient and his family) revealed gliosis and perivascular infiltration of lymphocytes and macrophages without vascular proliferation. There was no mitochondrial DNA mutations, deletion or duplication, including tRNA-Leu 3243, 8993, 3271, 9176, 3291, and tRNA-Lys 8344, 8356, and 8363. From these findings, a diagnosis of COX deficiency presenting as MELAS-like episodes was done. His mother also showed abnormality on aerobic exercise test, but she had no episode of stroke or neurological dysfunction. Six months later, his aphasia and apraxia of the right hand had resolved, and at discharge he was able to ambulate with a cane. Ten months later, he returned to his work. There has been no recurrence of neurologic symptoms over the next 3 years and 10 months. This patient appears to represent a rare case of adult onset COX deficiency presenting as MELAS-like episodes.
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PMID:[MELAS-like episodes in an adult case with cytochrome c oxidase deficiency]. 1523 72

Although linked with cardiac dysfunction, the association of MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) and pulmonary artery hypertension (PAH) has not been previously described. PAH and right ventricular heart failure were identified by echocardiography in a 3-year-old boy with a history of hypotonia, microcephaly and developmental delay. He initially presented with a 10-day history of dyspnoea, dependent oedema and reduced oral intake. Lactic acidosis was noted on serial arterial blood sampling and cerebrospinal fluid. Muscle biopsy demonstrated cytochrome-c oxidase-positive 'ragged-red' fibres consistent with MELAS; subsequent analyses revealed the m.3243A>G point mutation most commonly associated with MELAS. The mutation was heteroplasmic, representing 92% of the total mtDNA from a lung sample. Nitric oxide and epoprostenol were administered without significant clinical or echocardiographic improvement of his PAH. A 'mitochondrial cocktail' including biotin, riboflavin, carnitine and coenzyme Q10 also was provided. Five months after presentation, he developed seizures; MRI imaging of his brain demonstrated multiple focal lesions. His clinical status worsened with increasing cardiopulmonary failure. He died two months later. Although therapy for both MELAS and PAH remains limited, recent investigations suggest a beneficial role for l-arginine in both conditions, implying a possible common pathophysiology. Mitochondrial diseases such as MELAS should be considered in cases of idiopathic PAH, particularly when associated with multisystem involvement including short stature, hearing loss, renal dysfunction, retinopathy, diabetes mellitus, migraines, seizures, ophthalmoplegia, fatigability and weakness.
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PMID:Pulmonary artery hypertension in a child with MELAS due to a point mutation of the mitochondrial tRNA((Leu)) gene (m.3243A>G). 1818 Oct 29


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