Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0917816 (mental retardation)
 15,867 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The irradiation-fusion technique offers a means to isolate intact subchromosomal fragments of one mammalian species in the genetic background of another. Irradiation-reduced somatic cell hybrids can be used to construct detailed genetic and physical maps of individual chromosome bands and to systematically clone genes responsible for hereditary diseases on the basis of their chromosomal position. To assess this strategy, we constructed a panel of hybrids that selectively retain the portion of human chromosome band 11p13 that includes genes responsible for Wilms tumor, aniridia, genitourinary anomalies, and mental retardation (constituting the WAGR syndrome). A hamster-human hybrid containing the short arm of chromosome 11 as its only human DNA (J1-11) was gamma-irradiated and fused to a Chinese hamster cell line (CHO-K1). We selected secondary hybrid clones that express MIC1 but not MER2, cell-surface antigens encoded by bands 11p13 and 11p15, respectively. These clones were characterized cytogenetically by in situ hybridization with human repetitive DNA and were tested for their retention of 56 DNA, isozyme, and antigen markers whose order on chromosome 11p is known. These cell lines appear to carry single, coherent segments of 11p spanning MIC1, which range in size from 3000 kb to more than 50,000 kb and which are generally stable in the absence of selection. In addition to the selected region of 11p13, two cell lines carry extra fragments of the human centromere and two harbor small, unstable segments of 11p15. As a first step to determine the size and molecular organization of the WAGR gene complex, we analyzed a subset of reduced hybrids by pulsed-field gel electrophoresis. A small group of NotI restriction fragments comprising the WAGR complex was detected in Southern blots with a cloned Alu repetitive probe. One of the cell lines (GH3A) was found to carry a stable approximately 3000-kb segment of 11p13 as its only human DNA. The segment encompasses MIC1, a recurrent translocation breakpoint in acute T-cell leukemia (TCL2), and most or all of the WAGR gene complex, but does not include the close flanking markers D11S16 and delta J. This hybrid forms an ideal source of molecular clones for the developmentally fascinating genes underlying the WAGR syndrome.
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PMID:A panel of irradiation-reduced hybrids selectively retaining human chromosome 11p13: their structure and use to purify the WAGR gene complex. 215 97

The short arm of chromosome 11 carries genes involved in malformation syndromes, including the aniridia/genitourinary abnormalities/mental retardation (WAGR) syndrome and the Beckwith-Wiedemann syndrome, both of which are associated with an increased risk of childhood malignancy. Evidence comes from constitutional chromosomal aberrations and from losses of heterozygosity, limited to tumor cells, involving regions 11p13 and 11p15. In order to map the genes involved more precisely, we have fused a mouse cell line with cell lines from patients with constitutional deletions or translocations. Characterization of somatic cell hybrids with 11p-specific DNA markers has allowed us to subdivide the short arm into 11 subregions, 7 of which belong to band 11p13. We have thus defined the smallest region of overlap for the Wilms' tumor locus bracketed by the closest proximal and distal breakpoints in two of these hybrids. The region associated with the Beckwith-Wiedemann syndrome spans the region flanked by two 11p15.5 markers, HRAS1 and HBB. These hybrids also represent useful tools for mapping new markers to this region of the human genome.
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PMID:Characterization of a panel of somatic cell hybrids for subregional mapping along 11p and within band 11p13. Subdivision of the WAGR complex region. 272 95

Cockayne syndrome (CS) is an autosomal recessive disorder with dwarfism, mental retardation, sun sensitivity and a variety of other features. Cultured CS cells are hypersensitive to ultraviolet (UV) light, and following UV irradiation, CS cells are unable to restore RNA synthesis rates to normal levels. This has been attributed to a specific deficiency in CS cells in the ability to repair damage in actively transcribed regions of DNA at the rapid rate seen in normal cells. We have used the failure of recovery of RNA synthesis, following UV irradiation of CS cells, in a complementation test. Cells of different CS donors are fused. Restoration of normal RNA synthesis rates in UV-irradiated heterodikaryons indicates that the donors are in different complementation groups, whereas a failure to effect this recovery implies that they are in the same group. In an analysis of cell strains from 22 CS donors from several countries and different racial groups, we have assigned five cell strains to the CS-A group and the remaining 17 to CS-B. No obvious racial, clinical or cellular distinctions could be made between individuals in the two groups. Our analysis will assist the identification of mutations in the recently cloned CSA and CSB genes and the study of structure-function relationships.
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PMID:Genetic analysis of twenty-two patients with Cockayne syndrome. 883 35

Duchenne muscular dystrophy is a muscle-wasting disease accompanied by a variable, but often significant degree of mental retardation, possibly due to the absence of dystrophin. However, the function of brain type dystrophin remains insufficiently clear. With this background, in order to study the cell-specific regulation of brain type dystrophin expression in mice, we generated transgenic mice carrying the 2.1 kb 5'-fragment of the mouse brain type dystrophin gene, fused to the coding region of the bacterial lacZ gene. Three transgenic mice lines showed lacZ expression in the cerebral cortex. However, lacZ expression was not detected in the CA region of the hippocampus. These results suggest that the 2.1 kb 5'-fragment of the mouse brain type dystrophin gene contains the regulatory element required for its expression in the cerebral cortex, but not in the hippocampus.
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PMID:2.1 kb 5'-flanking region of the brain type dystrophin gene directs the expression of lacZ in the cerebral cortex, but not in the hippocampus. 909 55

Mutations in the gene encoding neural cell adhesion molecule L1 (L1CAM) are involved in X-linked hydrocephalus (HSAS, hydrocephalus due to stenosis of the aqueduct of Sylvius), MASA syndrome (mental retardation, aphasia, shuffling gait, and adducted thumbs), and spastic paraplegia type 1. We examined the L1CAM mutation in a Japanese family with HSAS for the purpose of DNA-based genetic counseling. The proband was a 9-year-old boy who had a 1-bp deletion in exon 22 of the L1CAM gene. This resulted in a shift of the reading frame, and introduction of a premature stop codon. Translation of this mRNA will create a truncated protein without the transmembrane domain, which cannot be expressed on the cell surface. Magnetic resonance images (MRI) revealed markedly enlarged lateral ventricles, hypoplastic white matter, thin cortical mantle, agenesis of the corpus callosum and septum pellucidum, and a fused thalamus. These findings represented impaired L1CAM function during development of the nervous system with resultant adhesion between neurons, neurites outgrowth and fasciculation, and neural cell migration. Screening by Apa I digestion of polymerase chain reaction (PCR) products identified the mother and the younger sister as heterozygous carriers. The carriers were asymptomatic. The father and the other sister did not have the mutation. The identification of L1CAM mutation in families with HSAS will give them the opportunity for DNA-based counseling and prenatal diagnosis.
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PMID:L1CAM mutation in a Japanese family with X-linked hydrocephalus: a study for genetic counseling. 944 Aug 2

This introductory article summarizes and comments on a group of four papers based in part on a panel discussion of craniosynostosis (CS) held at the 53rd annual meeting of the American Cleft Palate-Craniofacial Association. The purpose of this panel was to review the differential diagnosis of CS and the evidence for increased intracranial pressure (ICP) and developmental problems in CS patients. First, a correct diagnosis must be made, with true synostosis being differentiated from positional deformities and other normal variants. Second, medical indications must be balanced against the risks of operating on CS patients. Release of fused sutures is commonly undertaken to avoid increased ICP, although studies of ICP in infants and children with CS are hampered by a lack of normative data and by difficulties with measurement techniques. A subgroup of children with isolated craniosynostosis may have increased ICP, which can be deleterious to brain function. Longitudinal studies of children with isolated CS suggest an increased risk of mental retardation and learning disorders; surgical release of the suture may not diminish this risk. Patients with metopic suture fusion appear to be particularly at risk. These findings must be confirmed with a larger sample size. These uncertainties raise ethical issues and complicate medical decision-making for the infant with CS. A trusting and truthful relationship between the parents and the professional is necessary for a balanced discussion of the best interests of the child. All patients with confirmed synostosis should be followed for evidence of progressive deformity, intracranial hypertension, and neurodevelopmental problems.
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PMID:Controversies in the diagnosis and management of craniosynostosis: a panel discussion. 960 50

X-linked mental retardation is estimated to affect approximately 1 in 600 males. Although numerous genes responsible for syndromic mental retardation have been identified, the study of non-syndromic mental retardation suffers from intrinsic issues of genetic heterogeneity. During the investigation of three brothers with a contiguous gene deletion syndrome of Becker muscular dystrophy, glycerol kinase deficiency, congenital adrenal hypoplasia, and mental retardation, we found their dystrophin gene to be fused tail-to-tail with a gene encoding a novel member of the interleukin-1 receptor family, IL1RAPL1. This gene has a close relative in Xq22, which we call IL1RAPL2. Both IL1RAPL1 and IL1RAPL2 have novel C-terminal sequences not present in other related proteins, and are encoded by very large genes. The 1.8-megabase deletion in these patients removes not only the last exon of the dystrophin gene, the entire glycerol kinase and DAX-1 genes, and the MAGE-B gene cluster, but also three exons encoding the intracellular signalling domain of IL1RAPL1. The literature contains multiple reports of patients with non-syndromic mental retardation in association with an Xp22.1-Xp21.3 microdeletion of a marker which lies within the IL1RAPL1 gene. The gene is also wholly or partially deleted in patients with mental retardation as part of a contiguous deletion syndrome. We suggest that IL1RAPL1, and perhaps IL1RAPL2, are strong candidates for X-linked non-syndromic mental retardation loci, and that molecules resembling IL-1 and IL-18 play a role in the development or function of the central nervous system.
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PMID:Two novel members of the interleukin-1 receptor gene family, one deleted in Xp22.1-Xp21.3 mental retardation. 1075 39

Fragile X syndrome (FRAXA) is characterized at the molecular level by an expansion of a naturally occurring 5'-(CGG)(n)-3' repeat in the promoter and 5'-untranslated region (5'-UTR) of the fragile X mental retardation (FMR1) gene on human chromosome Xq27.3. When expanded, this region is usually hypermethylated. Inactivation of the FMR1 promoter and absence of the FMR1 protein are the likely cause of the syndrome. By using the bisulfite protocol of the genomic sequencing method, we have determined the methylation patterns in this region on single chromosomes of healthy individuals and of selected premutation carriers and FRAXA patients. In control experiments with unmethylated or M- Sss I-premethylated DNAs, this protocol has been ascertained to reliably detect all cytidines or 5-methylcytidines as unmethylated or methylated nucleotides, respectively. Analyses of the DNA from FRAXA patients reveal considerable variability in the lengths of the 5'-(CGG)(n)-3' repeats and in the levels of methylation in the repeat and the 5'-UTR. In one patient (OEl) with high repeat length hetero-geneity ( n = 15 to >200), shorter repeats (n = 20-80) were methylated or unmethylated, longer repeats ( n = 100-150) were often completely methylated, but one repeat with n = 160 proved to be completely unmethylated. This type of methylation mosaicism was observed in several FRAXA patients. In healthy females, methylated 5'-CG-3' sequences were found in some repeats and 5'-UTRs, as expected for the sequences from one of the X chromosomes. The natural FMR1 promoter is methylation sensitive, as demonstrated by the loss of activity in transfection experiments using the unmethylated or M- Sss I-premethylated FMR1 promoter fused to the luciferase gene as an activity indicator.
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PMID:Methylation mosaicism of 5'-(CGG)(n)-3' repeats in fragile X, premutation and normal individuals. 1077 84

The Interleukin-1 receptor (IL-1R) and Toll signaling pathways share the evolutionarily conserved Toll homology domain (THD), which is a critical component in the signaling cascade of the host defense responses to infection and inflammation. Our initial genomic database searches uncovered a novel THD signature sequence between DNA markers DXS87 and DXS366. The feasibility of subsequently applying a coordinated computational approach, including various exon-finding programs, homology-based searches, and receptor profile searches, in revealing the exons encoding this novel IL-1R family member is described. IL-1R9 shows restricted expression in fetal brain and is highly homologous to IL1RAPL (A. Carrie et al., 1999 Nat. Genet. 23: 25-31), which is reportedly involved in nonsyndromic X-linked mental retardation. These genes are scattered over separate genomic intervals in excess of 1.0 Mb and encode receptors with extended C-terminal tails. In our functional NF-kappaB reporter assays, IL1RAPL, IL-1R9, or versions lacking the extended C-terminal sequences failed in responding either to IL-1 directly or to IL-18 when various permutations of IL-18R ectodomain chimeras were fused to their cytoplasmic domains. Evolutionary sequence analyses reinforce our conclusion that these novel orphan receptors probably form a functionally distinct subset of the IL-1R superfamily.
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PMID:Computational identification, cloning, and characterization of IL-1R9, a novel interleukin-1 receptor-like gene encoded over an unusually large interval of human chromosome Xq22.2-q22.3. 1103 Nov 8

Myotonic dystrophy (DM) is a dominant neuromuscular disorder caused by the expansion of trinucleotide CTG repeats in the 3-untranslated region (3'-UTR) of the MtPK gene. Although DM-associated mental retardation suggests that neuronal functions are disturbed by the expansion mutation, the effect of this alteration in neuronal cells has not been approached. In this study we established stable transfectans of PC12 neuronal cell line expressing the reporter gene CAT alone (empty-vector clone) or fused to the MtPK 3'-UTR with 5, 60, or 90 CTG repeats (CTG5, CTG60, and CTG90 clones, respectively). CTG90 cells exhibited a suppression of NGF-induced neuronal differentiation while empty-vector, CTG5 and CTG60 clones differentiated normally. CTG90 cells displayed normal activation of early differentiation markers, ERK1/2, but the up-regulation of the late marker MAP2 was dramatically reduced. Our neuronal cell system provides the first information of how the mutant MtPK 3'-UTR mRNA affects neuronal functions.
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PMID:Expanded CTG repeats inhibit neuronal differentiation of the PC12 cell line. 1215 Sep 45


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