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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This article describes the neurologic presentations of children with mitochondrial disorders. The charts of 42 children with highly suspect mitochondrial disorders were reviewed. Thirty-seven children were diagnosed as having definite mitochondrial disorders based on a suggestive clinical presentation and at least one accepted criteria, while in five patients the diagnosis remained probable. All patients had nervous system involvement, but it was the presenting symptom in 28 of 42. Eighteen children had normal intelligence and 24 had mental retardation or developmental delay at the onset of their disease. Twenty-five patients had either an acute regression or a progressive encephalopathy. The most frequent neurologic manifestations were abnormal tone, seizures, extrapyramidal movements, and autonomic dysfunction. The eyes were involved in 11 children. Nerve deafness was found in seven patients. Myopathy was found in only six patients. In conclusion, a complex neurologic picture, especially with other organ involvement, warrants a full mitochondrial evaluation.
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PMID:Neurologic presentations of mitochondrial disorders. 1064 10

Myoclonic jerks occur in a number of different syndromes. There is many classifications of myoclonus. It is preferred the Fejerman classification, slightly modified that present the following five groups: 1. Myoclonus without encephalopathy and without epilepsy, which includes physiological myoclonus; 2. Encephalopathies with non epileptic myoclonus, which includes Kinsbourne syndrome and certain types of hyperekplexia which pose differential diagnosis problems with reflex myoclonic epilepsy; 3. Progressive encephalopathies with myoclonic seizures which includes typical and atypical progressive myoclonus epilepsies; 4. Epilepsies and epileptic encephalopathies with myoclonic seizures, which includes severe epilepsies which leads to mental retardation, as Otahara syndrome, West syndrome and Lennox-Gastaut syndrome, and other epilepsies which present sometimes myoclonic seizures, as Landau-Kleffner syndrome, 5. Comprises true myoclonic epilepsies, differentiating syndromes recognized as idiopathic, -benign myoclonic epilepsy of infancy, reflex form of benign myoclonic epilepsy in infancy, eyelid myoclonic with absences, perioral myoclonic with absences and juvenile myoclonic epilepsy-, cryptogenic-severe myoclonic epilepsy of infancy, myoclonic-astatic epilepsy and epilepsy with myoclonic absences-, and symptomatic as the generalized myoclonus in children with static encephalopathies. The epileptic syndromes of the last group are described. Despite this classification, apparently clear, there is still a great deal of confusion and in clinical practice, many cases are difficult to classify.
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PMID:[Myoclonus and myoclonic epilepsies in childhood]. 1071 97

Since the first description by Kanner (1943) the association between autistic disorder (AD) and epilepsy has been observed in 4-42% of patients. Some authors reported that seizures prevailed in adolescence but a systematic investigation has never been undertaken. We examined retrospectively 60 patients divided into two groups (with and without epilepsy and EEG paroxysmal abnormalities) with AD unrelated to a congenital or acquired encephalopathy (mean age 17 years 2 months). The aim was to investigate epilepsy, EEG paroxysmal abnormalities and possible etiological factors. The prevalence of epilepsy was 38.3%, much higher than that in a normal population of a similar age (6.6 per thousand). The prevalence of EEG paroxysmal abnormalities without epilepsy was 6.7%, higher than that in a population of adolescents and adults with psychiatric pathologies (2. 6%). Seizure onset was after age 12 years in 66.7% of cases. The most common type of epilepsy was partial in 65.2% and four patients (17.4%) had a benign childhood epilepsy with centro-temporal spikes. At the last observation 44.4% of patients had been seizure-free for 2 years or more. There were no organic factors influencing the development of epilepsy but familial and personal antecedents, mental retardation and CT scan/MRI data may suggest an early brain dysfunction responsible for AD and epilepsy.
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PMID:Epilepsy in adolescents and young adults with autistic disorder. 1072 61

The possible associations of myoclonic phenomenae, progressive or non-progressive encephalopathies and epileptic features are reviewed, with special emphasis on pediatric age. This leads to recognize the following five groups of conditions: (1) Myoclonus without encephalopathy and without epilepsy; (2) Encephalopathies with non-epileptic myoclonus; (3) Progressive encephalopathies presenting myoclonus seizures of epileptic syndromes (Progressive myoclonus epilepsies); (4) Epileptic encephalopathies with myoclonic seizures; (5) Myoclonic epilepsies. Within the first group, which also includes physiologic myoclonus, a more thorough description of "Benign sleep myoclonus of newborn" and "Benign myoclonus of early infancy" is given. Characteristics of group 2 are "Kinsbourne Syndrome" and certain types of "Hyperekplexia" which pose interesting differential diagnosis with stimulus-sensitive epilepsies. In group 3, the concept of progressive encephalopathies is stressed. The fourth group refers to severe epilepsies, mainly on infancy and childhood, which lead to mental retardation irrespective of their aetiology. Group 5 comprises the true myoclonic epilepsies, differentiating syndromes recognized as idiopathic--such as "Benign myoclonic epilepsy of infancy" and "Juvenile myoclonic epilepsy"--from those which are cryptogenic and carry a more cautious prognosis--as "Cryptogenic myoclonic and myoclonoastatic epilepsies" and "Severe myoclonic epilepsy of infancy". Other epileptic syndromes not usually considered as myoclonic epilepsies, but presenting sometimes as myoclonic seizures, are finally referred.
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PMID:Myoclonus and epilepsies. 1077 93

A cohort study at a tertiary care neonatal service was undertaken to determine the neurodevelopmental outcome of neonates who required intensive care. One hundred and nineteen nursery graduates were enrolled for follow up if they fulfilled any of the following risk factors: birth weight less than 1500 g, Apgar score less than 4 at 5 minutes, seizure(s), and required assisted ventilation for more than 24 hours. They were subjected to periodic clinical evaluation and administered the Bayley Scales of Infant Development in early childhood. Of the total infants enrolled, 101 completed the required follow up. They included 55 infants with birth weight < 1500 g, 45 with low Apgar scores, 12 with seizure(s) and 28 who received assisted ventilation. An overwhelming majority of subjects (85%) had normal neurodevelopmental outcome. The adverse outcome in the remaining 15 included mental retardation in all, subnormal motor development in 14, microcephaly in 1, hearing loss in 2 and visual impairment in 4. Among the neonatal risk factors, seizures, sepsis and hypoxic ischemic encephalopathy had a significant association with adverse outcome. Despite serious neonatal morbidity, the early neurodevelopmental outcome of nursery graduates was reasonably good. The association of neonatal sepsis with neurodevelopmental sequelae merits a prospective evaluation.
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PMID:Neurodevelopmental outcome of 'at risk' nursery graduates. 1077 50

Although for most children epilepsy is a relatively benign disorder, for some, epilepsy can be designated as "catastrophic" because the seizures are so difficult to control and because they are strongly associated with mental retardation. The catastrophic childhood epilepsies include uncommon disorders such as early infantile epileptic encephalopathy with suppression burst, severe myoclonic epilepsy of infancy, and epilepsy with myoclonic-astatic seizures. There are other syndromes that are relatively common such as infantile spasms, Lennox-Gastaut syndrome, and Sturge-Weber syndrome. Many children with catastrophic epilepsy have the seizures as a result of underlying brain abnormalities that will inevitably lead to mental retardation whether or not they have seizures. In some patients, however, the mental retardation appears to be caused by the seizures. Developmental plasticity provides children with an opportunity to recover from significant brain injuries. However, the plasticity may also be the cause of the mental retardation. In such patients, control of the seizures may lead to more normal intellectual development. Thus, every effort should be made to control seizures in children with catastrophic epilepsy.
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PMID:Catastrophic epilepsy in childhood. 1088 34

GLUT1 deficiency is caused by a defect in the facilitative glucose transporter GLUT1. Impaired glucose transport across brain tissue barriers is reflected by hypoglycorrhachia and results in an epileptic encephalopathy with developmental delay and motor disorders. Recently heterozygous mutations in the GLUT1 gene (1p35-31.3) have been reported in sporadic patients. Parents and siblings carried the GLUT1 wild-type, suggesting a de novo, autosomal dominant condition resulting from GLUT1 haploinsufficiency. We report a father and two children from separate marriages affected by GLUT1 deficiency and carrying a novel heterozygous missense mutation (G272A) in the GLUT1 gene. Mutations were identified by polymerase chain reaction and DNA sequencing and confirmed by restriction fragment digest. The predicted amino acid change (Gly91Asp) affects an Arg-X-Gly-Arg-Arg motif between helices 2 and 3 that represents a cytoplasmic anchor point and is highly conserved among transporters of the major facilitator superfamily down to yeast and bacteria. GLUT1 immunoreactivity was normal, but 3-O-methyl-D-glucose uptake into erythrocytes was significantly reduced, suggesting a quantitatively normal, but functionally impaired, GLUT1 protein at the cell membrane. This is the first report of autosomal dominant transmission of GLUT1 deficiency, confirming that this condition is the result of haploinsufficiency. The Gly-->Asp mutation within a highly conserved sequence highlights its importance for GLUT1 function. GLUT1 deficiency should be considered in patients with epilepsy, mental retardation and motor disorders. Our observations have bearing on the identification of this treatable disorder in pediatric and adult patients, will modify current biochemical protocols which use parental controls and will enable genetic counseling of affected families.
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PMID:Autosomal dominant transmission of GLUT1 deficiency. 1113 15

Rett syndrome (RTT) is an X-linked dominant neurodevelopmental disorder that manifests in females, typically after the first year of life. It is a leading cause of mental retardation and autistic behavior in girls and women; a hallmark of the disease is incessant hand movements in the form of wringing, twisting, or clapping. It was recently discovered that RTT is caused by mutations in the methyl-CpG-binding protein 2 (MECP2) gene. MECP2 assists in the transcriptional silencing process via DNA methylation; we hypothesize that disruption of this gene alters the normal developmental expression of various other genes, some of which must account for the peculiar neurologic phenotype of RTT. Molecular studies have identified MECP2 mutations in up to 80% of classic RTT patients; mutation type has some effect on the phenotypic manifestation of RTT, but the pattern of X inactivation seems to determine phenotypic severity. Favorable (skewed) X inactivation can so spare a patient from the effects of mutant MECP2 that they display only the mildest learning disability or no phenotype at all. The unmitigated impact of mutant MECP2 can be inferred from the few males who have been born into RTT kindreds with such severe neonatal encephalopathy that they did not survive their second year. MECP2 mutations thus manifest in a far broader array of phenotypes than classic RTT. This discovery should prove helpful in diagnosing cases of mild learning disability or severe neonatal encephalopathies of unknown cause and also should provide insight into the pathogenesis of RTT.
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PMID:Rett syndrome: methyl-CpG-binding protein 2 mutations and phenotype-genotype correlations. 1118 Feb 22

Rett syndrome, a neurodevelopmental disorder that is a leading cause of mental retardation in females, is caused by mutations in the X-linked gene encoding methyl-CpG-binding protein 2 (MeCP2). MECP2 mutations have subsequently been identified in patients with a variety of clinical syndromes ranging from mild learning disability in females to severe mental retardation, seizures, ataxia, and sometimes neonatal encephalopathy in males. In classic Rett syndrome, genotype-phenotype correlation studies suggest that X chromosome inactivation patterns have a more prominent effect on clinical severity than the type of mutation. When the full range of phenotypes associated with MECP2 mutations is considered, however, the mutation type strongly affects disease severity. MeCP2 is a transcriptional repressor that binds to methylated CpG dinucleotides throughout the genome, and mutations in Rett syndrome patients are thought to result in at least a partial loss of function. Abnormal gene expression may thus underlie the phenotype. Discovering which genes are misregulated in the absence of functional MeCP2 is crucial for understanding the pathogenesis of this disorder and related syndromes.
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PMID:Molecular genetics of Rett syndrome and clinical spectrum of MECP2 mutations. 1126 31

Rett syndrome is a neurodevelopmental disorder characterized by cognitive and adaptive regression with autistic features, loss of acquired skills, and stereotypic hand movements that almost exclusively affects females. It is an X-linked dominant disorder, with presumed lethality in males. Nonetheless, there are a few descriptions of males suspected of having Rett syndrome. With the recent discovery that the MECP2 gene is responsible for most cases of Rett syndrome, it is possible to molecularly assess cases of affected males by direct sequencing analysis. We describe an Israeli family consisting of a female having classic Rett syndrome and a male sibling with severe neonatal encephalopathy. Molecular analysis revealed that both sister and brother have the same MECP2 gene mutation; however, their mother does not. This case, as well as other published studies of males with MECP2 mutations, reveals that the clinical manifestations in viable males vary from neonates with severe encephalopathy to adults with mental retardation and demonstrate genotype-phenotype correlations.
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PMID:Rett syndrome: clinical manifestations in males with MECP2 mutations. 1191 64


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