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)

L1 disease is a group of overlapping clinical phenotypes including X-linked hydrocephalus, MASA syndrome, spastic paraparesis type 1, and X-linked agenesis of corpus callosum. The patients are characterized by hydrocephalus, agenesis or hypoplasia of corpus callosum and corticospinal tracts, mental retardation, spastic paraplegia, and adducted thumbs. The responsible gene, L1CAM, encodes the L1 protein which is a member of the immunoglobulin superfamily of neuronal cell adhesion molecules. The L1 protein is expressed in neurons and Schwann cells and seems to be essential for nervous system development and function. The patients' gene mutations are distributed over the functional protein domains. The exact mechanisms by which these mutations cause a loss of L1 protein function are unknown. There appears to be a relationship between the patients' clinical phenotype and the genotype. Missense mutations in extracellular domains or mutations in cytoplasmic regions cause milder phenotypes than those leading to truncation in extracellular domains or to non-detectable L1 protein. Diagnosis of patients and carriers, including prenatal testing, is based on the characteristic clinical picture and DNA mutation analyses. At present, there is no therapy for the prevention or cure of patients' neurological disabilities.
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PMID:Genetic and clinical aspects of X-linked hydrocephalus (L1 disease): Mutations in the L1CAM gene. 1143 88

Since the identification of the ATRX gene (synonyms XNP, XH2) in 1995, it has been shown to be the disease gene for numerous forms of syndromal X-linked mental retardation [X-linked alpha thalassemia/mental retardation (ATR-X) syndrome, Carpenter syndrome, Juberg-Marsidi syndrome, Smith-Fineman-Myers syndrome, X-linked mental retardation with spastic paraplegia]. An attempt is made in this article to review the clinical spectrum associated with ATRX mutations and to analyse the evidence for any genotype/phenotype correlation.
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PMID:Molecular-clinical spectrum of the ATR-X syndrome. 1144 89

The L1 adhesion molecule regulates axon growth and is mutated in the X-linked mental retardation syndrome CRASH (acronym for corpus callosum agenesis, retardation, aphasia, spastic paraplegia, hydrocephalus). A novel role for L1 as a potentiator of neuronal cell migration to extracellular matrix proteins through beta1 integrins and intracellular signaling to mitogen-activated protein (MAP) kinase was identified. L1 potentiated haptotactic migration of B35 neuroblastoma cells toward fibronectin, vitronectin, and laminin through the signaling intermediates c-Src, phosphatidylinositol-3 kinase, and MAP kinase. L1 potentiated migration toward fibronectin through alpha5beta1 integrin in human embryonic kidney 293 cells and depended on determinants of L1 endocytosis: dynamin I, c-Src, and the AP2/clathrin binding site (Arg-Ser-Leu-Glu) in the neuronal splice form of L1. L1 clustering on the cell surface enhanced the internalization of activated beta1 integrins and L1 into distinct endocytic vesicles. L1-potentiated migration, enhancement of beta1 integrin endocytosis, and activation of MAP kinase were coordinately inhibited by mutation of an RGD sequence in the sixth immunoglobulin-like domain of L1. Moreover, three CRASH mutations in the L1 cytoplasmic domain (1194L, S1224L, Y1229H), two of which interfere with ankyrin association, inhibited L1-potentiated migration and MAP kinase activation. Function-blocking antibodies to L1 and beta1 integrin retarded the migration of 5-bromo-2'-deoxyuridine-labeled mouse cerebellar granule cells in slice cultures, underscoring the potential physiological relevance of these findings. These studies suggest that L1 functionally interacts with beta1 integrins to potentiate neuronal migration toward extracellular matrix proteins through endocytosis and MAP kinase signaling, and that impairment of this function by L1 cytoplasmic domain mutations may contribute to neurological deficits in CRASH.
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PMID:The neural cell adhesion molecule L1 potentiates integrin-dependent cell migration to extracellular matrix proteins. 1207 89

Two families, originally diagnosed as having nonsyndromic X-linked mental retardation (NSXLMR), were reviewed when it was shown that they had a 24-bp duplication (428-45 1dup(24bp)) in the ARX gene [Stromme et al., 2002: Nat Genet 30:441-445]. This same duplication had also been found in three other families: one with X-linked infantile spasms and hypsarrhythmia (X-linked West syndrome, MIM 308350) and two with XLMR and dystonic movements of the hands (Partington syndrome, MIM 309510). On review, manifestations of both West and Partington syndromes were found in some individuals from both families. In addition, it was found that one individual had autism and two had autistic behavior, one of whom had epilepsy. The degree of mental retardation ranged from mild to severe. A GCG trinucleotide expansion (GCG)10+7 and a deletion of 1,517 bp in the ARX gene have also been found in association with the West syndrome, and a missense mutation (1058C>T) in a family with a newly recognized form of myoclonic epilepsy, severe mental retardation, and spastic paraplegia [Scheffer et al., 2002: Neurology, in press]. Evidently all these disorders are expressions of mutations in the same gene. It remains to be seen what proportions of patients with infantile spasms, focal dystonia, autism, epilepsy, and nonsyndromic mental retardation are accounted for by mutations in the ARX gene.
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PMID:Variable expression of mental retardation, autism, seizures, and dystonic hand movements in two families with an identical ARX gene mutation. 1237 46

Neural cell adhesion molecule L1 is an important molecule mediating cell-cell interactions during the development of nervous system. L1 can promote axonal outgrowth and is related with nerve cell migration, and therefore L1 plays an important role both in the development and maintaince of the nervous system. In humans, mutations in the L1 gene can lead to mental retardation, spastic paraplegia, hydrocephalus, and other developmental abnormalities. The molecular mechanisms of mutations in L1 gene to induce inherited neurological diseases are not clear. In present investigation, a transgenic DNA of mouse L1 extracellular domain (L1ECD) was constructed by adding a stop codon to the end of L1ECD cDNA and then putting it under the control of CAMK II promoter, which is active specifically in the brain. To verify this construct, L1ECD cDNA was subcloned into an expression vector pCEP4 and then transfected the C6 cells. The expression of L1ECD cDNA in C6 cells was confirmed by Northern blotting and the effects of L1ECD on the growth rate and morphology of C6 cells in vitro as well as primarily cultured neurons were observed. The L1ECD constructs were microinjected into the fertilized zygotes of C57BL/6 mice. The transgenic mice thus produced were identified by Southern and Northern hybridization analysis. The results demonstrated that the L1ECD was integrated in the genome of transgenic mice and expressed specifically in the brain.
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PMID:[Effect of L1ECD on mouse primarily cultured neurons and construction of transgenic mice specifically expressing L1ECD in brain]. 1254 2

We have recently mapped a new rare form of spastic paraplegia complicated by bilateral cataracts, gastroesophageal reflux with persistent vomiting, and amyotrophy to chromosome 10q23.3-q24.2. This locus, named SPG9, is located in an interval spanning about 12 cM of genomic DNA, between markers D10S536 and D10S603, where different neurological disorders have been mapped. In particular, a gene for partial epilepsy has been assigned to a 3 cM interval between markers D10S185 and D10S577, which is completely included in the SPG9 critical region. A few families affected with spastic paraplegia and epilepsy have been reported; in the present study, we tested a pedigree with concurrence of spastic paraplegia, epilepsy, and mental retardation inherited as an autosomal dominant trait, using markers located in the SPG9 interval. Haplotype reconstruction excluded the linkage to 10q23.3-q24.2. In addition, the seven different loci so far reported to be associated with autosomal dominant pure forms of spastic paraplegia have been tested and excluded by linkage analysis and haplotype reconstruction, including SPG4 on chromosome 2p22-p21, where a familial form of spastic paraplegia associated with dementia and epilepsy has been mapped. These data confirm genetic heterogeneity in familial spastic paraplegia with epilepsy and suggest a specific locus for the family here analyzed.
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PMID:Genetic heterogeneity in inherited spastic paraplegia associated with epilepsy. 1256 7

An adult female patient is presented with macrocephaly, mental retardation, seizures, spastic paraplegia and distinctive craniofacial appearance. We believe she represents the fourth case of the Fryns macrocephaly, distinct craniofacial appearance and spastic paraplegia syndrome. Cardinal features are discussed and additional phenotypic manifestations are discussed.
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PMID:Macrocephaly, distinct craniofacial appearance, and spastic paraplegia: a new case and expansion of the phenotype. 1515 Jul 92

We found mutations in the gene PQBP1 in 5 of 29 families with nonsyndromic (MRX) and syndromic (MRXS) forms of X-linked mental retardation (XLMR). Clinical features in affected males include mental retardation, microcephaly, short stature, spastic paraplegia and midline defects. PQBP1 has previously been implicated in the pathogenesis of polyglutamine expansion diseases. Our findings link this gene to XLMR and shed more light on the pathogenesis of this common disorder.
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PMID:Mutations in the polyglutamine binding protein 1 gene cause X-linked mental retardation. 1463 49

X-linked hydrocephalus (hydrocephalus due to congenital stenosis of aqueduct of Sylvius; MIM number 307000) has a variable clinical expression. About 5% of cases of non-syndromal hydrocephalus are affected by this condition. The severe clinical phenotype is characterized by hydrocephalus and adducted thumbs in a newborn boy, the milder phenotype by mental retardation and spastic paraplegia. Female carriers may show mild features. Mutations in the LiCAM gene have been demonstrated to cause the condition. The gene is located at Xq28 and encodes for a cell surface glycoprotein that consists of an extracellular part with 6 immunoglobulin and 5 fibronectin type III-like domains, a single pass transmembrane domain and a short cytoplasmic domain. Mutations are documented in about 75% of classical cases. Reliable prenatal diagnosis is possible when a mutation has been documented.
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PMID:[From gene to disease; X-linked hydrocephalus and LiCAM]. 1532 48

X-linked hydrocephalus, HSAS (hydrocephalus due to stenosis of aqueduct of Sylvius), MASA (mental retardation, aphasia, shuffling gait, and adducted thumbs), and CRASH (corpus callosum hypoplasia, retardation, adducted thumbs, spastic paraplegia, and hydrocephalus) syndromes are allelic disorders. X-linked hydrocephalus and associated phenotypes are due to mutations in the L1CAM gene, which has been identified as a coding neural cell adhesion molecule. We report two cases of L1 spectrum disorders within the same family. The first case was diagnosed by ultrasonographic examination prenatally and the second case was diagnosed postnatally. Both patients and their mothers carry a novel mutation of the L1CAM gene. In this family, nine X-linked hydrocephalus and five female carriers were found in three generations, and molecular genetic analysis was performed to detect the asymptomatic carriers.
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PMID:A novel L1CAM mutation with L1 spectrum disorders. 1566 85


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