Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Children with chronic metabolic acidosis should be investigated to determine the presence of an organic acid, especially when the plasma electrolyte profile shows a deficiency of anion. One of the organic acids that should be looked for in such a patient is lactic acid. Lactic acidosis due to tissue hypoxia is a well-known phenomenon (e.g., in shock and cardiopulmonary disease) and has not been discussed in this essay; nor has lactic acidosis due to exogenous causes like infusion of fructose or sorbitol, or admiministration of phenformin. Chronic lactic acidosis in infancy is a rare condition. It may be associated with glycogen storage disease Type 1, fructose diphosphatase deficiency, methylmalonic acidemia, propionic acidemia, pyruvate carboxylase or dehydrogenase deficiency and Leigh's subacute necrotizing encephalomyelopathy (SNE). Some patients with chronic lactic acidosis do not have nay of these diseases and comprise an "idiopathic" group. This is a heterogeneous group, probably having several different causes for the metabolic error. In Leigh's SNE, a metabolic block in the formation of thiamine triphosphate in brain has been demonstrated and has been attributed to the presence of an inhibitor of thiamine pyrophosphate-adenosine triphosphate (TPP-ATP) phosphoryl transferase in body fluids. The inhibitor has also been encountered in cases of intermittent cerebellar ataxia and of primary hypoventilation (Ondine's curse), which may represent variants of Leigh's disease. Increased blood levels of lactate, pyruvate and alanine frequently are encountered in SNE, but it still is not clear whether they are due to a primary or secondary disturbance in the catabolism of pyruvate. Disturbed lactate and pyruvate metabolism has also been encountered in isolated cases of mental retardation and growth failure, in mitochondrial myopathies and in polyneuropathies, and may be expected to occur in Wernicke's encephalopathy. Finally, it has been noted in malignancy and in association with other rare metabolic disorders.
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PMID:Lactic acidosis in childhood. 17 59

Studies on the growth and development of patients with Bartter's syndrome indicate that severe growth retardation occurs during infancy and early childhood. Delayed adolescent growth spurt has occurred in all patients studied thus far who had manifested the syndrome during infancy. Normal stature is eventually attained. Mental development ranges from normal to brain damage and dysfunction; however, the majority of patients show some degree of mental retardation. The coexistence of Leigh's encephalopathy with Bartter's syndrome in one patient and the finding of severe motor and congnitive retardation with communicating hydrocephalus in another indicate that the prognosis of mental development in some cases of Bartter's syndrome is guarded. Particular attention should be given to maintaining normal nutritional status in all patients, particularly during infancy and early childhood.
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PMID:Growth characteristics in patients with Bartter's syndrome. 22 May 47

The purpose of the study was differential diagnosis of lactic acidosis in 44 children aged from 2 weeks to 4 years. In all of them the lactate level in repeated determinations exceeded 27 mg/100 ml. From the point of view of clinical manifestations the children were divided into three groups: 26 with hepatomegaly and hypoglycaemia (I), 6 with ataxia and retardation of somatic development (II), 12 with mental retardation and muscular hypotonia (III). Together with basic biochemical studies other tests were done, if necessary, including glucose and alanine loading, lactate determination in cerebrospinal fluid, analysis of urinary organic acids by the GC-MS method, morphological examinations of muscle biopsy material, enzymatic determinations in liver biopsy material. In group I glycogenosis was suspected and its type was finally established after biochemical and enzymatic tests (types I, Ib, III, VI, VIa, XI). In one case fructose-1,6-diphosphatase deficiency was suspected. In group II the clinical manifestations resembled Leigh's syndrome. The tests demonstrated an inhibition of glucose formation from alanine, and lactate level in the cerebrospinal fluid was evidently raised above that in the serum. Gasometric index showed the presence of respiratory alkalosis with metabolic compensation rather than primary lactate acidosis. In group III, with considerable clinical variety of signs, in only nine out of 12 children the cause of lactate acidosis could have been established (pathological changes of mitochondria in 4 cases, secondary increase of lactate without pathogenetic importance in 4, and 3-hydroxy-3-methylglutaric acidosis in 1 case. In conclusion it is thought that this combination of diagnostic methods is useful in differential diagnosis of congenital lactate acidosis in children.
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PMID:Congenital lactic acidosis in children--differential diagnosis in 44 cases. 184 18

Two patients with mitochondrial encephalomyopathy (MEP) serve to emphasize the variability of this group of diseases. Cerebral insults, mitochondrial cardiopathy, relapsing ileus, cerebral angioma, ataxia, and myoclonic seizures characterized the first case of an adult man with similar diseases in his family, interpreted as transitional form between mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) and myoclonus epilepsy associated with ragged red fibers (MERRF). The second patient, a floppy infant with cardiomyopathy and myoclonism, statomotoric and mental retardation showed combined defects in mitochondrial respiratory chain at NADH-CoQ reductase and cytochrome c oxidase and a deficiency of carnitine. In both patients neuropathologically criteria of Leigh's syndrome could be demonstrated in the cerebral cortex, in case 2 also clinically. The classificatory problems of the relationships between KSS, MELAS, MERRF, Leigh's as well as Alpers' syndromes are discussed.
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PMID:Mitochondrial myopathies with necrotizing encephalopathy of the Leigh type. 322 73

Seven hundred five cases of agenesis of the corpus callosum (ACC) are reviewed from the literature (n = 660) and from our own observations (n = 45). The diagnosis was made or confirmed using neuroradiological techniques (n = 519) and necropsy or surgery (n = 231). Association with abnormalities often of chromosomes 8, 11, 13-15 and 18 suggests their involvement in abnormal corpus callosum (CC) morphogenesis. Four syndromes (e.g. Aicardi, acrocallosal, Andermann and Shapiro) are characterized by ACC, while others are only sporadically associated (e.g. fetal alcohol syndrome, Dandy-Walker syndrome, Leigh disease, Arnold-Chiari II syndrome). In non-Aicardi patients, the male-to-female ratio was 3:2 and X-linked recessive inheritance is postulated to play a role in some cases. Common abnormalities in acallosal patients included: mental retardation (MR), 73% [corrected]; seizures, 42%; ocular anomalies, 42%; gyral abnormalities, 32%; hydrocephalus, 23%; other central nervous system (CNS) lesions, 29%; costovertebral defects, 24%. Developmental disabilities are not attributable to absence of the CC per se, but due to other CNS malformation or dysfunction, which may be genetic or non-genetic. Future research using recombinant DNA techniques will enable isolation and identification of specific chromosomal defects in those cases with a genetic abnormality.
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PMID:Clinicopathological findings associated with agenesis of the corpus callosum. 331 Jul 13

Fourteen patients (10 boys, 4 girls) aged from 4 months to 14 years old were diagnosed with mitochondrial disease based on the clinical manifestations together with abnormal muscle mitochondrial morphologies. Their clinical diagnoses included Leigh syndrome, three; Menkes' syndrome, three; Kearns-Sayre syndrome, two; myoclonic epilepsy with ragged fibres, one; and infant-onset progressive myoclonic epilepsy, one; fatal infantile mitochondrial myopathy, one; fatty acid oxidation defect, two; and myopathy with cardiopathy, one. Organs involved other than muscles included central nervous system, ten; heart, six; eye, two; liver, two; and kidney, two. Clinical manifestations varied to include hypotonia, seizures, myoclonus, mental retardation, nystagmus, ataxia, ptosis, ophthalmoplegia, retinal degeneration, muscle atrophy, spasticity etc. Nine had an abnormal rise in lactate after glucose loading. Ragged-red fibres were found in four patients. Abnormal mitochondrial morphology included abnormal accumulation, abnormal cristae pattern of tubular, concentric, or parallel form, some contained osmiophilic inclusion bodies. One patient of Leigh syndrome had had brain necropsy which showed intramyelin splitting of myelinated axons.
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PMID:Clinical manifestation of mitochondrial diseases in children. 821 54

Using magnetic resonance imaging (MRI), we studied the myelination of the brains of 8 patients with West syndrome. All cases were symptomatic, 2 having severe asphyxia, 1 lissencephaly, 1 Leigh encephalopathy, 2 tuberous sclerosis, 1 multiple anomalies and 1 microcephaly. Myelination of the pons, cerebellum, thalamus, internal capsules, optic radiation, centrum semiovale and cerebral white matter was separately assessed. The 2 cases with tuberous sclerosis exhibited normal myelination patterns, although asymmetry of the cerebral white matter was noted. These cases had a moderate degree of mental retardation and persistent seizures. The other 6 cases exhibited a marked delay of myelination throughout the central nervous system except for the midbrain. These cases had severe psychomotor retardation and persistent seizures. Although the difference in the outcome may simply reflect the different etiological disorders, these results suggest that the myelination pattern is related to the psychomotor retardation but not to the severity of the seizures in West syndrome. Atrophy of the corpus callosum developed during ACTH therapy and disappeared after the therapy. It was thus suggested that the callosal atrophy caused by the ACTH therapy was reversible.
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PMID:An MRI study of the myelination pattern in West syndrome. 883 97

Neuropathy, ataxia, and retinitis pigmentosa (NARP) syndrome and maternally inherited Leigh's syndrome have been associated with T8993G point mutations in the mitochondrial adenosine triphosphatase 6 gene. Typically, NARP syndrome is characterized by developmental delay, seizures, dementia, retinitis pigmentosa, ataxia, sensory neuropathy, and proximal weakness. Usually, there is a correlation between the percentage of mutated mitochondrial DNA and clinical severity, and when mutated mitochondrial DNA is > 90%, it is often seen with Leigh's syndrome. We now report a family with mitochondrial DNA T8993G mutation in eight living members, five with mutant mitochondrial DNA >90% and one with 20% mutant mitochondrial DNA. However, their clinical features include variable combinations of seizures, behavior problems, learning disability, mental retardation, sensorineural deafness, cerebellar ataxia, and proximal muscle weakness. No retinitis pigmentosa was found in all eight living members, including a 56-year-old grandmother. Only one dead female relative was diagnosed with Leigh's syndrome on the neuropathologic examination at age 22 years, when she died of an accident. High mitochondrial DNA T8993G mutation is not always associated with typical features of Leigh's and NARP syndromes.
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PMID:High mitochondrial DNA T8993G mutation (<90%) without typical features of Leigh's and NARP syndromes. 1145 54

We report a nine-year-old boy with the features of Leigh syndrome (LS) and a severe cytochrome-c oxidase (COX) deficiency with a single thymidine insertion at nucleotide position 5537 (T 5537i) in the tRNA Trp gene of mitochondrial DNA. During infancy the boy was irritable and hypotonus was noticed. Early motor development was delayed, although mental development seemed normal until eight months of age. Early neurological signs were nystagmus, hypertonus and optic atrophy. Severe seizures and mental retardation developed subsequently. Major findings on neuroradiological investigation were from the brainstem, thalami and white matter compatible with LS. Spectrophotometric analysis of skeletal muscle mitochondria showed a profound COX deficiency and a marked complex I deficiency. Enzyme-histochemical analysis showed reduced COX activity in the majority of the muscle fibres. There were no ragged red fibres. The T 5537i mutation was found in a high proportion (> 95 %) in blood, liver and muscle tissue of the patient and in blood of the patient's mother (81 %). This mutation has previously been described in one family in which one child had a very high proportion of the T 5537i mutation and clinical features of LS. We conclude that, although mtDNA mutations are considered to be rare in LS with COX deficiency, the T 5537i mutation should be screened for in cases of LS with COX deficiency when SURF1 gene mutations have been excluded, especially when complex I activity is also decreased.
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PMID:Leigh syndrome with cytochrome-c oxidase deficiency and a single T insertion nt 5537 in the mitochondrial tRNATrp gene. 1277 30

Lactic acidosis has been associated with a variety of clinical conditions and can be due to mutation in nuclear or mitochondrial genes. We performed mutations screening of all mitochondrial tRNA genes in 44 patients who referred as hyperlactic acidosis. Patients showed heterogeneous phenotypes including Leigh disease in four, MELAS in six, unclassified mitochondrial myopathy in 10, cardiomyopathy in five, MERRF in one, pure lactic acidosis in six, and others in 12 including facio-scaplo-femoral muscular dystrophy (FSFD), familial cerebellar ataxia, recurrent Reye syndrome, cerebral palsy with mental retardation. We measured enzymatic activities of pyruvate dehydrogenase complex, and respiratory chain enzymes. All mitochondrial tRNA genes and known mutation of ATPase 6 were studied by single strand conformation polymorphism (SSCP), automated DNA sequence and PCR-RFLP methods. We have found one patient with PDHC deficiency and six patients with Complex I+IV deficiency, though the most of the patients showed subnormal to deficient state of respiratory chain enzyme activities. We have identified one of the nucleotide changes in 29 patients. Single nucleotide changes in mitochondrial tRNA genes are found in 27 patients and one in ATPase 6 gene in two patients. One of four pathogenic point mutations (A3243G, C3303T, A8348G, and T8993G) was identified in 12 patients who showed the phenotype of Leigh syndrome, MELAS, cardimyopathy and cerebral palsy with epilepsy. Seventeen patients have one of the normal polymorphisms in the mitochondrial tRNA gene reported before. SSCP and PCR-RFLP could detect the heteroplasmic condition when the percentage of mutant up to 5, however, it cannot be observed by direct sequencing method. It is important to screen the mtDNA mutation not only by direct sequence but also by PCR-RFLP and the other sensitive methods to detect the heroplasmy when lactic acidosis has been documented in the patients who are not fulfilled the criteria of mitochondrial disorders.
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PMID:Mitochondrial tRNA gene mutations in patients having mitochondrial disease with lactic acidosis. 1633 22


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