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

We present the first pathologic descriptions of the puppet-like syndrome of Angelman based on autopsy studies of a 21-year-old woman. The noteworthy findings were a small brain with mild cerebral atrophy but normal gyral development. There was marked cerebellar atrophy with loss of Purkinje and granule cells and extensive Bergmann's gliosis. Study of dendrite morphology using Golgi impregnations of the visual cortex revealed a prominent decrease in dendritic arborization of layer 3 and layer 5 pyramidal neurons. Quantitative Golgi analysis also revealed a significant decrease in the numbers of dendritic spines in apical layer 3 dendrites and both apical and basal layer 5 dendrites. Neurochemical studies of frozen brain tissue demonstrated markedly reduced gamma-aminobutyric acid content in the cerebellar cortex, as well as elevated glutamate content in the frontal and occipital cortices. Although there are no definite morphologic correlates of many of the clinical signs, the pronounced dendritic pathology and neurochemical abnormalities in cerebral cortex may provide a physiologic basis for mental retardation.
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PMID:Puppet-like syndrome of Angelman: a pathologic and neurochemical study. 200 12

After establishing more extended reference values for amino acids, purines and pyrimidines in cerebrospinal fluid (CSF) in infancy and childhood, we studied 1250 CSF-aliquots from patients who were undergoing a diagnostic lumbar puncture for diverse clinical indications. Our primary aim was to answer the question whether determination of the concentration of amino acids, purines and pyrimidines in CSF is a useful tool in screening for metabolic disorders in children with unexplained mental retardation. In unexplained mental retardation (95 patients) we observed varying abnormalities of CSF. These were reproducible in only 2 patients (a decrease of homocarnosine in combination with two unidentified compounds). Striking abnormalities in pyrimidine content which are limited to CSF are found in argininosuccinic aciduria and uraemia. In uraemia a general decrease in amino acids in CSF and increase of gamma-aminobutyric acid (GABA) was observed. The results obtained indicate that determination of amino acids, purines and pyrimidines in CSF is only of limited value in the diagnosis of unexplained mental retardation.
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PMID:Cerebrospinal fluid amino acids, purines and pyrimidines as a tool in the study of metabolic brain diseases. 841 13

D-2-Hydroxyglutaric aciduria has been observed in patients with extremely variable clinical symptoms, creating doubt about the existence of a disease entity related to the biochemical finding. An international survey of patients with D-2-hydroxyglutaric aciduria was initiated to solve this issue. The clinical history, neuroimaging, and biochemical findings of 17 patients were studied. Ten of the patients had a severe early-infantile-onset encephalopathy characterized by epilepsy, hypotonia, cerebral visual failure, and little development. Five of these patients had a cardiomyopathy. In neuroimaging, all patients had a mild ventriculomegaly, often enlarged frontal subarachnoid spaces and subdural effusions, and always signs of delayed cerebral maturation. In all patients who underwent neuroimaging before 6 months, subependymal cysts over the head or corpus of the caudate nucleus were noted. Seven patients had a much milder and variable clinical picture, most often characterized by mental retardation, hypotonia, and macrocephaly, but sometimes no related clinical problems. Neuroimaging findings in 3 patients variably showed delayed cerebral maturation, ventriculomegaly, or subependymal cysts. Biochemical findings included elevations of D-2-hydroxyglutaric acid in urine, plasma, and cerebrospinal fluid in both groups. Cerebrospinal fluid gamma-aminobutyric acid was elevated in almost all patients investigated. Urinary citric acid cycle intermediates were variably elevated. The conclusion of the study is that D-2-hydroxyglutaric aciduria is a distinct neurometabolic disorder with at least two phenotypes.
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PMID:D-2-Hydroxyglutaric aciduria: biochemical marker or clinical disease entity? 989 84

The tolerability and drug interaction profiles of 6 new anticonvulsants: oxcarbazepine, vigabatrin, lamotrigine, gabapentin, tiagabine and topiramate, are reviewed. In general, these new anticonvulsants are well tolerated and drug interaction problems are minor with the exception of the risk of failure of oral contraceptives during treatment with oxcarbazepine or topiramate. In this review, the clinical implications of the tolerability of these drugs are discussed for different patient groups. The choice of which new anticonvulsant for which patient depends upon individual factors, in particular, seizure type, tolerability and practical administration factors. Treating elderly patients may be complicated by an increased sensitivity to adverse effects as these patients very often receive polytherapy for accompanying diseases. Drugs with very simple pharmacokinetic properties may be preferred in this group. Women of childbearing age face specific problems related to the epilepsy and to treatment with anticonvulsants. These include impaired fertility, failure of oral contraceptives and the risk of birth defects. Some new anticonvulsants may be suggested in preference to classical drugs to avoid these problems, but the human experience with newer anticonvulsants is still limited and, therefore, so is knowledge of the risk of congenital malformations in the offspring of mothers taking anticonvulsants. Psychiatric and behavioural changes frequently complicate treatment of patients with mental retardation. Some of the new anticonvulsants, in particular those affecting the gamma-aminobutyric acid (GABA) system such as vigabatrin, seem to exacerbate this problem and should be used with caution in these patients.
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PMID:Newer anticonvulsants: comparative review of drug interactions and adverse effects. 1092 28

Down syndrome (DS) is a genetic disease with developmental brain abnormalities resulting in early mental retardation and precocious, age-dependent Alzheimer-type neurodegeneration. Furthermore, non-cognitive symptoms may be a cardinal feature of functional decline in adults with DS. A number of amino acids [glutamate, aspartate, gamma-aminobutyrate (GABA), glycine, taurine, glutamine, serine, arginine] were investigated in post-mortem tissue samples from temporal, occipital cortex, thalamus, caudate nucleus, and cerebellum of adult patients with Down syndrome (DS) exhibiting Alzheimer-like neuropatholgy, Alzheimer's disease (AD) and from controls by use of high performance liquid chromatography (HPLC). In DS, no significant differences from control values could be observed in any of the brain regions. In AD, significant loss of GABA content was found in the temporal cortex (0.5+/-0.2 micromol/g vs. 1.3+/-0.8 micromol/g wet weight tissue, P<0.01), occipital cortex (0.8+/-0.2 micromol/g vs. 1.4+/-0.6 micromol/g, P<0.05) and cerebellum (1.1+/-0.3 micromol/g vs. 1.8+/-0.5 micromol/g, P<0.05). Glutamate and aspartate concentrations were significantly reduced in the caudate nucleus of AD subjects (glutamate: 6.1+/-3.4 micromol/g vs. 14.7+/-1.8 micromol/g; aspartate: 1.5+/-0.3 micromol/g vs. 3.3+/-0.4 micromol/g, P<0.05). The results of this study confirm previous findings in late stage AD and provide further information with respect to DS which may be relevant to understanding different pathogenesis of cognitive and non-cognitive (behavioral) features in DS and AD.
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PMID:Differences between GABA levels in Alzheimer's disease and Down syndrome with Alzheimer-like neuropathology. 1121 66

The RSH/Smith--Lemli--Opitz syndrome (RSH/SLOS) is a human autosomal recessive syndrome characterized by multiple malformations, a distinct behavioral phenotype with autistic features and mental retardation. RSH/SLOS is due to an inborn error of cholesterol biosynthesis caused by mutation of the 3 beta-hydroxysterol Delta(7)-reductase gene. To further our understanding of the developmental and neurological processes that underlie the pathophysiology of this disorder, we have developed a mouse model of RSH/SLOS by disruption of the 3 beta-hydroxysterol Delta(7)-reductase gene. Here we provide the biochemical, phenotypic and neurophysiological characterization of this genetic mouse model. As in human patients, the RSH/SLOS mouse has a marked reduction of serum and tissue cholesterol levels and a marked increase of serum and tissue 7-dehydrocholesterol levels. Phenotypic similarities between this mouse model and the human syndrome include intra-uterine growth retardation, variable craniofacial anomalies including cleft palate, poor feeding with an uncoordinated suck, hypotonia and decreased movement. Neurophysiological studies showed that although the response of frontal cortex neurons to the neurotransmitter gamma-amino-n-butyric acid was normal, the response of these same neurons to glutamate was significantly impaired. This finding provides insight into potential mechanisms underlying the neurological dysfunction seen in this human mental retardation syndrome and suggests that this mouse model will allow the testing of potential therapeutic interventions.
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PMID:Biochemical, phenotypic and neurophysiological characterization of a genetic mouse model of RSH/Smith--Lemli--Opitz syndrome. 1123 Jan 74

Inverted duplicated chromosome 15 (Inv dup [15]) syndrome is a genetic disorder characterized by psychologic or intellectual language delay; neurologic signs, such as hypotonia, ataxia, and epilepsy; mental retardation ranging from mild to severe; and facial dysmorphisms. All patients present with a psychopathologic impairment that is highly variable in severity but always classifiable as pervasive developmental disorder (PDD). Many genetic mechanisms have been hypothesized to explain the clinical variability. This article describes the neurologic and psychopathologic features of six Inv dup(15) patients, one male and five females, between 8 and 14 years of age, all with a maternal marker chromosome. Four patients were diagnosed with PDD not otherwise specified, whereas two patients received a diagnosis of autism. Epilepsy was present in three patients (two generalized symptomatic and one focal symptomatic), and a correlation between the severity of the disease and its outcome was not always observed. Nevertheless, the influence of gene content of the marker chromosome, particularly the three gamma-aminobutyric acid-A receptor subunit genes, may represent the link between epilepsy, mental retardation, and PDD.
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PMID:Relationship between clinical and genetic features in "inverted duplicated chromosome 15" patients. 1127 59

In recent years, improvement in diagnostic techniques has led to better recognition of "disorders of cortical development". These disorders constitute a significant cause of epilepsy, mental retardation, developmental delay and neurological deficits in childhood, and may also contribute to the pathogenesis of psychological and neurodegenerative diseases in adults. Hitherto, however, few systematic studies of the human fetal cortex have been performed, and little is known about the ontogenetic processes of the neocortex in man. The aim of the study is to establish an understanding of the developmental events that occur in the second and third trimesters of gestation, by investigating the biochemical patterns of development of the human neocortex during this period. The temporal and spatial patterns of expression of the neuronal markers gamma-aminobutyric acid (GABA), choline acetyltransferase (ChAT), dopamine beta hydroxylase (DBH), dopamine receptor DR1 and synaptophysin, as well as the glial cell markers glial fibrillary acidic protein (GFAP), S100B and excitatory amino acid transporter protein GLT-1 are delineated in the fetal cortex using immunohistochemistry. Results of this study showed that different neuronal and glial cell proteins follow different developmental patterns and many show inter- or intra-regional variations in expression. Details of these patterns are described and discussed. The early expression of these proteins suggests that they play important roles in the developmental processes of cell proliferation, migration and differentiation. Both neurotransmitters and glial cell proteins probably function outside the confines of synapses in the fetal brain, as paracrine/autocrine factors. Early developmental events seem to be dictated by an innate programme, whereas late events may be more susceptible to extrinsic influences. It is hoped that knowledge of the normal developmental process can lead to better understanding of the causes and mechanisms of "disorders of cortical development", and to better treatments.
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PMID:Development of the human cerebral cortex: a histochemical study. 1259 27

Succinic semialdehyde dehydrogenase (SSADH) deficiency is a rare autosomal recessive disorder affecting CNS gamma-aminobutyric acid (GABA) degradation. SSADH, in conjunction with GABA transaminase, converts GABA to succinate. In the absence of SSADH, GABA is converted to 4-OH-butyrate. The presence of 4-OH-butyrate, a highly volatile compound, may be undetected on routine organic acid analysis. Urine organic acid testing was modified at the authors' institution in 1999 to screen for the excretion of 4-OH-butyrate by selective ion monitoring gas chromatography-mass spectrometry in addition to total ion chromatography. Since then, five patients with 4-hydroxybutyric aciduria have been identified. The authors add the clinical, neuroimaging, and EEG findings from a new cohort of patients to 51 patients reported in the literature with clinical details. Ages ranged from 1 to 21 years at diagnosis. Clinical findings include mild-moderate mental retardation, disproportionate language dysfunction, hypotonia, hyporeflexia, autistic behaviors, seizures, and hallucinations. Brain MRI performed in five patients at the authors' institution revealed symmetric increased T2 signal in the globus pallidi. SSADH deficiency is an under-recognized, potentially manageable neurometabolic disorder. Urine organic acid analysis should include a sensitive method for the detection of 4-hydroxybutyrate and should be obtained from patients with mental retardation or neuropsychiatric disturbance of unknown etiology.
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PMID:Clinical spectrum of succinic semialdehyde dehydrogenase deficiency. 1274 23

Succinic semialdehyde dehydrogenase deficiency is a rare disorder of the degradation pathway of gamma-aminobutyric acid. The disorder is detected when 4-hydroxybutyric aciduria is present on urine organic acid analysis, and is subsequently confirmed by enzyme measurement on leucocytes. The disorder has been identified in approximately 350 individuals worldwide. We review the clinical features in 60 patients. The most common characteristics are developmental delay maximally involving expressive language, hypotonia, mental retardation, ataxia, and behavioral problems. Seizures occur in approximately half of patients, and include tonic-clonic, absence, and myoclonic seizures, including status epilepticus. Electroencephalographic findings are background slowing and generalized and focal epileptiform discharges. Magnetic resonance imaging typically reveals increased T2-weighted signal of the globus pallidus bilaterally, with variable involvement of white matter and the cerebellar dentate nucleus. Preliminary human cerebrospinal fluid measurements are consistent with neurometabolic aberrations documented in the murine animal model, with elevations in gamma-aminobutyric acid, gamma-hydroxybutyrate, and homocarnosine, and low glutamine. Succinic semialdehyde dehydrogenase deficiency may be an underrecognized neurometabolic disorder with a nonspecific and wide phenotypic spectrum, and carries implications for a comprehensive fundamental understanding of interrelations between multiple neurotransmitter systems.
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PMID:Succinic semialdehyde dehydrogenase deficiency in children and adults. 1289 57


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