Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004352 (autism)
 32,579 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fragile X syndrome, an X-linked dominant disorder with reduced penetrance, is associated with intellectual and emotional disabilities ranging from learning problems to mental retardation, and mood instability to autism. It is most often caused by the transcriptional silencing of the FMR1 gene, due to an expansion of a CGG repeat found in the 5'-untranslated region. The FMR1 gene product, FMRP, is a selective RNA-binding protein that negatively regulates local protein synthesis in neuronal dendrites. In its absence, the transcripts normally regulated by FMRP are over translated. The resulting over abundance of certain proteins results in reduced synaptic strength due to AMPA receptor trafficking abnormalities that lead, at least in part, to the fragile X phenotype.
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PMID:Fragile X syndrome. 1839 41

Fragile X syndrome (FXS) is a common inherited form of mental retardation that is caused, in the vast majority of cases, by the transcriptional silencing of a single gene, fmr1. The encoded protein, FMRP, regulates mRNA translation in neuronal dendrites, and it is thought that changes in translation-dependent forms of synaptic plasticity lead to many symptoms of FXS. However, little is known about the potentially extensive changes in synaptic protein content that accompany loss of FMRP. Here, we describe the development of a high-throughput quantitative proteomic method to identify differences in synaptic protein expression between wild-type and fmr1-/- mouse cortical neurons. The method is based on stable isotope labeling by amino acids in cell culture (SILAC), which has been used to characterize differentially expressed proteins in dividing cells, but not in terminally differentiated cells because of reduced labeling efficiency. To address the issue of incomplete labeling, we developed a mathematical method to normalize protein ratios relative to a reference based on the labeling efficiency. Using this approach, in conjunction with multidimensional protein identification technology (MudPIT), we identified >100 proteins that are up- or down-regulated. These proteins fall into a variety of functional categories, including those regulating synaptic structure, neurotransmission, dendritic mRNA transport, and several proteins implicated in epilepsy and autism, two endophenotypes of FXS. These studies provide insights into the potential origins of synaptic abnormalities in FXS and a demonstration of a methodology that can be used to explore neuronal protein changes in neurological disorders.
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PMID:Quantitative proteomic analysis of primary neurons reveals diverse changes in synaptic protein content in fmr1 knockout mice. 1882 39

Fragile X syndrome is the most common inherited form of cognitive deficiency in humans and perhaps the best-understood single cause of autism. A trinucleotide repeat expansion, inactivating the X-linked FMR1 gene, leads to the absence of the fragile X mental retardation protein. FMRP is a selective RNA-binding protein that regulates the local translation of a subset of mRNAs at synapses in response to activation of Gp1 metabotropic glutamate receptors (mGluRs) and possibly other receptors. In the absence of FMRP, excess and dysregulated mRNA translation leads to altered synaptic function and loss of protein synthesis-dependent plasticity. Recent evidence indicates the role of FMRP in regulated mRNA transport in dendrites. New studies also suggest a possible local function of FMRP in axons that may be important for guidance, synaptic development, and formation of neural circuits. The understanding of FMRP function at synapses has led to rationale therapeutic approaches.
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PMID:Fragile X syndrome: loss of local mRNA regulation alters synaptic development and function. 1895 14

Loss of the mRNA-binding protein FMRP results in the most common inherited form of both mental retardation and autism spectrum disorders: fragile X syndrome (FXS). The leading FXS hypothesis proposes that metabotropic glutamate receptor (mGluR) signaling at the synapse controls FMRP function in the regulation of local protein translation to modulate synaptic transmission strength. In this study, we use the Drosophila FXS disease model to test the relationship between Drosophila FMRP (dFMRP) and the sole Drosophila mGluR (dmGluRA) in regulation of synaptic function, using two-electrode voltage-clamp recording at the glutamatergic neuromuscular junction (NMJ). Null dmGluRA mutants show minimal changes in basal synapse properties but pronounced defects during sustained high-frequency stimulation (HFS). The double null dfmr1;dmGluRA mutant shows repression of enhanced augmentation and delayed onset of premature long-term facilitation (LTF) and strongly reduces grossly elevated post-tetanic potentiation (PTP) phenotypes present in dmGluRA-null animals. Null dfmr1 mutants show features of synaptic hyperexcitability, including multiple transmission events in response to a single stimulus and cyclic modulation of transmission amplitude during prolonged HFS. The double null dfmr1;dmGluRA mutant shows amelioration of these defects but does not fully restore wildtype properties in dfmr1-null animals. These data suggest that dmGluRA functions in a negative feedback loop in which excess glutamate released during high-frequency transmission binds the glutamate receptor to dampen synaptic excitability, and dFMRP functions to suppress the translation of proteins regulating this synaptic excitability. Removal of the translational regulator partially compensates for loss of the receptor and, similarly, loss of the receptor weakly compensates for loss of the translational regulator.
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PMID:Metabotropic glutamate receptor-mediated use-dependent down-regulation of synaptic excitability involves the fragile X mental retardation protein. 1903 65

Autism, which is common in individuals with fragile X syndrome, is often difficult to diagnose. We compared the diagnostic classifications of two measures for autism diagnosis, the ADOS and the ADI-R, in addition to the DSM-IV-TR in 63 males with this syndrome. Overall, 30% of the subjects met criteria for autistic disorder and 30% met criteria for PDD-NOS. The classifications on the ADOS and DSM-IV-TR were most similar, whereas the ADI-R classified subjects as autistic much more frequently. We further investigated the relationship of both FMRP and FMRI mRNA to symptoms of autism in this cohort and found no significant relationship between the measures of autism and molecular features, including FMRP, FMRI mRNA, and CGG repeat number.
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PMID:Autism profiles of males with fragile X syndrome. 1912 54

The high concordance for autism symptoms in monozygotic twin-pairs compared to di-zygotic twins and/or non-twin sib-ships suggests a high genetic determinism in autism. Those results have hypothesized multi-factorial determinism in accordance with family studies and mathematical models. However, linkage and association or candidate gene strategies have failed to-date to identify clearly involved mechanisms. Mental retardation (MR) is known as frequently associated to autism. Multiplex XLMR pedigrees have been reported with only one mutated patient having autism and MR: different X-located MR genes have been shown to be involved (NLGN4, MECP2, OPHN1, ZNF674 and FRAXA) which does not suggest that they could be "autism genes". Tuberous sclerosis studies and report of numerous autosomal domains shown deleted in MR-autistic subjects suggest that several autosomal dominant (AD) genes could be also involved in MR with autism. Whereas multiplex AD-MR families are rare, AD de novo mutations could explain numerous sporadic situations of non-specific MR and of autism with MR, in accordance with twin studies. Finally, we hypothesize that in those autistic subjects with mendelian MR, the XL-MR or AD-MR gene (G1) would pave the way for a second Mendelian factor (G2) responsible for autism symptoms.
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PMID:Could autism with mental retardation result from digenism and frequent de novo mutations? 1916 Jan 28

CGG repeat expansions in the 5' noncoding region of the fragile X mental retardation 1 gene (FMR1) give rise to both neurodevelopmental and neurodegenerative human diseases depending on the length of the expansion. Expansions beyond 200 repeats (full mutation) generally result in gene silencing and fragile X syndrome (FXS), the leading heritable form of cognitive impairment and autism. Smaller expansions (55-200 CGG repeats; "premutation") give rise to the neurodegenerative disorder fragile X-associated tremor/ataxia syndrome (FXTAS) through an entirely distinct, toxic mRNA gain-of-function mechanism. A rapid means for both high-risk and newborn screening for allele size would provide a greater opportunity for early intervention and family counseling as well as furnish critical data on repeat size distribution and expanded allele frequencies. In the current work, we propose a novel mass spectrometry (MS) based method for the rapid identification of expanded CGG repeats to complement a recently described polymerase chain reaction (PCR) method for large population screening. In this combined approach, the optimized PCR method is used to amplify the relevant region of FMR1, followed by extensive nonspecific nuclease digestion. The resulting oligonucleotides are analyzed by MS in a manner that provides the relative proportion of triplet repeat oligonucleotides in seconds per sample. This assay enables swift and reproducible detection of expanded CGG alleles using a single blood spot and in principle is suitable for large scale studies and newborn screening. Moreover, this analytical scheme establishes a unique new intersection of MS with molecular biology, with potential for significant interdisciplinary impact.
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PMID:Polymerase chain reaction, nuclease digestion, and mass spectrometry based assay for the trinucleotide repeat status of the fragile X mental retardation 1 gene. 1951 25

Fragile X syndrome, the main cause of inherited mental retardation, is caused by transcriptional silencing of the fragile X mental retardation gene, FMR1. Absence of the associated protein FMRP leads to the dysregulation of many genes creating a phenotype of ADHD, anxiety, epilepsy and autism. The core aim of this review is to summarise two decades of molecular research leading to the characterisation of cellular and molecular pathways involved in the pathology of this disease and as a consequence to the identification of two new promising targets for rational therapy of fragile X syndrome, namely the group 1 metabotrope glutamate receptors (Gp1 mGluRs) and the gamma-amino butyric acid A receptors (GABA(A)Rs). As no current clinical treatments are directed specifically at the underlying neuronal defect due to absence of FMRP, this might open new powerful therapeutic strategies.
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PMID:Fragile X syndrome: from molecular genetics to therapy. 1972 10

Loss of fragile X mental retardation 1 (FMR1) gene function is the most common cause of inherited mental retardation and autism spectrum disorders, characterized by attention disorder, hyperactivity and disruption of circadian activity cycles. Pursuit of effective intervention strategies requires determining when the FMR1 product (FMRP) is required in the regulation of neuronal circuitry controlling these behaviors. In the well-characterized Drosophila disease model, loss of the highly conserved dFMRP causes circadian arrhythmicity and conspicuous abnormalities in the circadian clock circuitry. Here, a novel Sholl Analysis was used to quantify over-elaborated synaptic architecture in dfmr1-null small ventrolateral neurons (sLN(v)s), a key subset of clock neurons. The transgenic Gene-Switch system was employed to drive conditional neuronal dFMRP expression in the dfmr1-null mutant background in order to dissect temporal requirements within the clock circuit. Introduction of dFMRP during early brain development, including the stages of neurogenesis, neuronal fate specification and early pathfinding, provided no rescue of dfmr1 mutant phenotypes. Similarly, restoring normal dFMRP expression in the adult failed to restore circadian circuit architecture. In sharp contrast, supplying dFMRP during a transient window of very late brain development, wherein synaptogenesis and substantial subsequent synaptic reorganization (e.g. use-dependent pruning) occur, provided strong morphological rescue to reestablish normal sLN(v)s synaptic arbors. We conclude that dFMRP plays a developmentally restricted role in sculpting synaptic architecture in these neurons that cannot be compensated for by later reintroduction of the protein at maturity.
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PMID:Temporal requirements of the fragile x mental retardation protein in modulating circadian clock circuit synaptic architecture. 1973 24

We report on a 7-year-old girl with severe mental retardation (MR), autism, micro-brachycephaly, generalized muscle hypotonia with distal hypotrophy of lower limbs, scoliosis and facial dysmorphisms. Array-CGH analysis identified a 1.1 Mb deletion of chromosome Xq22.1. Further analysis demonstrated that the deletion was inherited from her mother who showed mild MR, short stature, brachycephaly, epilepsy and a Borderline Personality Disorder. Microsatellite segregation analysis revealed that the rearrangement arose de novo in the mother on the paternal X chromosome. The deleted Xq22.1 region contains part of the NXF gene cluster which is involved in mRNA nuclear export and metabolism. Among them, the NXF5 gene has already been linked to mental retardation whereas NXF2 protein has been recently found to be partner of FMRP in regulating Nxf1 mRNA stability in neuronal cells. The dosage imbalance of NXF5 and NXF2 genes may explain the severe phenotype in our patient.
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PMID:Familial 1.1 Mb deletion in chromosome Xq22.1 associated with mental retardation and behavioural disorders in female patients. 2009 87


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