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

The most common inherited form of hydrocephalus, X linked hydrocephalus (HSAS), is characterised by mental retardation, adducted thumbs, and spastic paraplegia. Genetic analysis has mapped the locus for HSAS to subchromosomal band Xq28 within a region of approximately 2 megabases of DNA. In order to refine the location of the disease gene we have conducted genetic linkage analysis with Xq28 marker loci in four additional HSAS families. A lod score of 4.26 with polymorphic marker DXS52 (St14) confirms the linkage of HSAS to Xq28. Identification of a recombination event between the HSAS gene and Xq28 loci F8C and DXS605 (2-19) reduces the size of the interval likely to contain the disease locus to about 1.5 megabases, the distance between DXS605 and DXS52. The locus for neural cell adhesion molecule, L1CAM, maps within this interval and therefore represents a candidate gene for HSAS.
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PMID:Refining the genetic location of the gene for X linked hydrocephalus within Xq28. 847 7

L1 is a neuronal cell adhesion molecule with important functions in the development of the nervous system. The gene encoding L1 is located near the telomere of the long arm of the X chromosome in Xq28. We review here the evidence that several X-linked mental retardation syndromes including X-linked hydrocephalus (HSAS), MASA syndrome, X-linked complicated spastic paraparesis (SP1) and X-linked corpus callosum agenesis (ACC) are all due to mutations in the L1 gene. The inter- and intrafamilial variability in families with an L1 mutation is very wide, and patients with HSAS, MASA, SP1 and ACC can be present within the same family. Therefore, we propose here to refer to this clinical syndrome with the acronym CRASH, for Corpus callosum hypoplasia, Retardation, Adducted thumbs, Spastic paraplegia and Hydrocephalus.
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PMID:CRASH syndrome: clinical spectrum of corpus callosum hypoplasia, retardation, adducted thumbs, spastic paraparesis and hydrocephalus due to mutations in one single gene, L1. 855 2

Mental retardation, hydrocephalus, and agenesis of the corpus callosum are observed both in fetal alcohol syndrome (FAS) and in children with mutations in the gene for the cell adhesion molecule L1. We studied the effects of ethanol on cell-cell adhesion in mouse fibroblasts transfected with human L1. L1-transfected fibroblasts exhibited increased cell-cell adhesion compared with wild-type or vector-transfected controls. Ethanol potently and completely inhibited L1-mediated adhesion both in transfected L cells and NIH/3T3 cells. Half-maximal inhibition was observed at 7 mM ethanol, a concentration achieved in blood and brain after ingesting one alcoholic beverage. In contrast, ethanol did not inhibit the adhesion of fibroblasts transfected with vector alone or with N-CAM-140. L1-mediated cell-cell adhesion was inhibited with increasing potency by n-propanol and n-butanol, but was not inhibited at all by n-alcohols of 5 to 8 carbons, acetaldehyde, or acetate, suggesting that ethanol interacts directly with a small hydrophobic pocket within L1. Phenylalanine, teratogenic anticonvulsants, and high concentrations of glucose did not inhibit L1-mediated cell-cell adhesion. Ethanol also inhibited potently the heterotypic adhesion of rat cerebellar granule cells to a monolayer of L1-transfected NIH/3T3 cells, but had no effect on their adhesion to N-CAM-140 or vector-transfected NIH/3T3 cells. Because L1 plays a role in both neural development and learning, ethanol inhibition of L1-mediated cell-cell interactions could contribute to FAS and ethanol-associated memory disorders.
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PMID:Alcohol inhibits cell-cell adhesion mediated by human L1. 860 70

The cell adhesion molecule L1 plays an important role in neural development. We have previously demonstrated that the second immunoglobulin-like domain (Ig2) of L1 contains both homophilic binding and neuritogenic activities (Zhao, X., and Siu, C.-H. (1995) J. Biol. Chem. 270, 29413-29421). Recently, two mutations (R184Q and H210Q) within the Ig2 region of the human L1 gene have been shown to be responsible for X-linked hydrocephalus and the related MASA (mental retardation, aphasia, shuffling gait, and adducted thumbs) syndrome. Glutathione S-transferase-Ig2 fusion proteins containing these mutations were used to evaluate their effects on L1. The homophilic binding activity of fusion proteins and their ability to promote neurite outgrowth from retinal cells were examined. The R184Q mutation led to a complete loss of both homophilic binding and neuritogenic activities, while the H210Q mutation resulted only in a partial loss. These results provide, for the first time, direct demonstration of the deleterious effects of hydrocephalus/MASA mutations on two intrinsic properties of L1.
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PMID:Differential effects of two hydrocephalus/MASA syndrome-related mutations on the homophilic binding and neuritogenic activities of the cell adhesion molecule L1. 863 66

Two patients with X-chromosomal hydrocephalus internus (aqueduct stenosis, clasped thumbs, mental retardation and spasticity) habe been described. In both cases the family history revealed further affected relatives. The intra- and interfamilial variability of this rare X-chromosomal recessive disease will be demonstrated. In this context differentialdiagnoses like X-linked MASA syndrome and X-linked spastic paraplegia have been discussed on the basis of a variable expressivity of different mutations in the same gene.
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PMID:[X-chromosomal recessive hydrocephalus internus: a separate disease picture? 2 further case reports and review of the literature]. 867 3

Fifty-five infants who presented bacterial neonatal meningitis were prospectively studied to analyze the frequency and the type of sequelae. All the infants were full term newborns. There were 38 boys and 17 girls; the age of disease onset varied from 3 to 28 days. The causative organism was represented mainly by enterobacteriae. The median time of follow-up was 5 years. The frequency of neurologic sequelae was 63.7%, represented mainly by neuropsychomotor development delay (58.2%), hydrocephaly (45.5%) and convulsions (34.5%). Severe motor abnormalities ocurred in 23.6% of children (quadriplegia, diplegia, hemiparesia and ataxia). Convulsions in the acute phase of the disease and the positive cerebrospinal fluid culture were highly associated to sequelae. The school performance, obtained in 25 children, showed presence of disabilities in 48% of cases, which were significantly associated to mental retardation.
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PMID:[Neonatal bacterial meningitis: prospective study of the long-term outcome of 55 children]. 873 49

Neurofibromatoses (NF1 and NF2) are genetic diseases with an extremely wide range of manifestations, particularly NF1. In order to gain insight into their prognosis, we have conducted a follow-up study of 100 patients with neurofibromatoses, 89 NF1 patients and 11 NF2 patients all of them presenting neurological manifestations. Four deaths occurred in the NF1 group (3 neurofibrosarcomas) and two in the NF2 group (after neurosurgery). We describe a series of NF1 brainstem tumors as being pilocytic astrocytomas, much less aggressive than non-NF1 brainstem tumors but more symptomatic than brainstem UBOs ('unidentified bright objects') in NF1. The series of optic nerve tumors also demonstrate the poor and non-progressive evolution of tumors with the same histopatological estructure. Hydrocephalus related to aqueductal stenosis is a frequent and tratable manifestation in NF1 patients. Data are presented which suggest that a severe form of NF2 is much more frequent than a mild form but it is rule that number and progressivity of tumors render the prognosis always severe in NF2 patients. A long term follow-up study has been carried among 20 patients with tuberous sclerosis: patients who presented seizures before the age of 5 years have mental retardation in spite of disappearing, often spontaneously, the seizures. The initial symptoms in Von Hippel-Lindau patients depend often on the hemangioblastoma of the spinal cord and a strict control is proposed for patients with risk of suffering spinal-cerebello-retino hemangioblastomatosis. Other phakomatoses are also being considered in their general prognosis.
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PMID:[Natural evolution of neurocutaneous syndrome in adults]. 875 48

X-linked hydrocephalus (HSAS) is the most common form of inherited hydrocephalus characterized by hydrocephalus due to stenosis of the aqueduct of Sylvius, mental retardation, clasped thumbs, and spastic paraparesis. MASA syndrome (mental retardation, aphasia, shuffling gait and adducted thumbs) and SPG1 (X-linked complicated spastic paraplegia) are also X-linked disorders with overlapping clinical signs. Linkage analysis studies implicated the neural cell adhesion molecule L1 (L1CAM) gene as a candidate gene for these X-linked disorders. This genetic study analyzes the L1CAM gene in a Japanese family with members suffering from HSAS, and describes a deletion of five nucleotides in exon 8. Screening by Bg1I digestion of polymerase chain reaction (PCR) products revealed that two siblings have the same mutation and a sister was identified as a heterozygous carrier. The 5 nucleotide deletion causes a shift of the reading frame and introduces a premature stop codon 72 nucleotides downstream, which might result in a truncated protein. The mutation identified herein is a novel L1CAM mutation, which triggers hydrocephalus. We report a unique L1CAM mutation that causes HSAS: the first report of such a mutation in a Japanese family.
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PMID:A deletion of five nucleotides in the L1CAM gene in a Japanese family with X-linked hydrocephalus. 878 80

Deletions of the short arm of chromosome 6 are relatively rare, only 16 cases having been described in the literature so far. Here we present a detailed investigation by fluorescence in situ hybridisation of two further cases with different but overlapping interstitial deletions involving 6p22, 6p23 and 6p24. The main features involved are craniofacial malformations, heart and kidney defects, mental retardation/developmental delay, hypotonia and hydrocephalus. By using 36 yeast artificial chromosome and cosmid clones from a contig covering 6p22.3-6p25 and other probes with defined cytogenetic locations within 6p21-6p22 we have precisely localised the breakpoints involved in each of the cases, estimated the sizes of the deleted regions and defined the region that is hemizygously deleted in both cases.
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PMID:A detailed investigation of two cases exhibiting characteristics of the 6p deletion syndrome. 879 22

Joubert's syndrome is a rare developmental defect of the cerebellar vermis associated with episodic hyperpnea and apnea, abnormal eye movements, and mental retardation. The condition is usually diagnosed clinically during the neonatal period. This article reports nine patients with the syndrome (six males, three females; ages ranging from 2.5 to 9 yrs), and describes MR imaging findings in seven of these. Besides the previously described characteristic and relatively common changes of the syndrome, the MR imaging findings in these patients revealed thinned optic tracts, enlarged temporal horns in the absence of hydrocephalus, high-signal of the cerebral periventricular white matter, abnormal signal in the decussation of the superior cerebellar peduncles, and abnormal embryonic vessels associated with the dysplastic folia of the cerebellar hemispheres.
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PMID:MR imaging of Joubert's syndrome. 879 70


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