Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

A recent study by Ingram et al. [2000b: Teratology 62:393-405] suggests a (His)73(Arg) polymorphism (A:G) in HOXA1 contributes substantially to a liability for autism. Using 68 individuals diagnosed with Autism Spectrum Disorders, they found a significant dearth of G homozygotes and biased transmission of G alleles from parents to affected offspring, especially from mothers. Because the connection between HOXA1 and liability to autism is compelling, we attempted to replicate their finding using a larger, independent sample from the Collaborative Programs of Excellence in Autism (CPEA) network. In our data, genotype frequencies conform to Hardy-Weinberg equilibrium; allele transmissions meet Mendelian expectations; and there is no obvious sex-biased allele transmission. Based on our sample size, calculations suggest that we would have at least 95% power to detect linkage and association even if the A:G polymorphism were to account for only 1% of the heritability of autism. Therefore, although we cannot exclude the possibility that the samples in the two studies are intrinsically different, our data from our sample argue against a major role for HOXA1 (His)73(Arg) in liability to autism.
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PMID:No evidence for linkage of liability to autism to HOXA1 in a sample from the CPEA network. 1221 Feb 85

The substrate-binding sites in membrane transporters are alternately accessible from either side of the membrane, but the molecular basis of how this alternate opening of internal and external gates is achieved is largely unknown. Here we present data indicating that, in the neuronal electrogenic sodium- and potassium-coupled glutamate transporter EAAC-1, the substrate-binding site and one of the gates, or a residue controlling the gating process, are in close physical proximity. Arginine 445, located only two residues away from a residue implicated in glutamate binding (Bendahan, A., Armon, A., Madani, N., Kavanaugh, M. P., and Kanner, B. I. (2000) J. Biol. Chem. 275, 37436-37442), has been mutated to serine (R445S). Upon expression in oocytes, measurements of l-[(3)H]-glutamate transport under voltage clamp reveal that the charge/flux ratio for l-glutamate at -60 mV is approximately 30-fold higher than that of the wild type. Also, with d-aspartate, R445S exhibits an approximately 15-fold increase in this ratio. In contrast to the wild type, the reversal potential of the substrate-dependent currents in R445S shifts to more negative potentials when either the external sodium or potassium concentration is decreased. These findings indicate that these two cations are the main current carriers in the R445S mutant. Introduction of a methionine or a glutamine, but not a lysine, at position 445 gives rise to a phenotype similar to R445S. Therefore, it seems that the elimination of a positive charge in the vicinity of the substrate-binding site converts the transporter into a glutamate-gated cation-conducting pathway.
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PMID:Arginine 445 controls the coupling between glutamate and cations in the neuronal transporter EAAC-1. 1459 97

Autism is a neuro-developmental syndrome that affects 0.1-0.5% of the population. It has been proposed that alterations in neuronal circuitry and/or neuronal signaling are responsible for the behavioral and cognitive aberrations in autism patients. However, the cellular basis of such alterations is unknown. Recently, point mutations in a family of neuronal cell adhesion molecules called neuroligins have been linked to autism-spectrum disorders and mental retardation. We investigated the consequences of these disease-associated mutations on neuroligin function. We demonstrate that the point mutation at arginine 451 and a nonsense mutation at aspartate 396 of neuroligin-3 and -4 (NL3 and NL4), respectively, result in intracellular retention of the mutant proteins. Over-expression of wild-type NL3 and NL4 proteins in hippocampal neurons stimulates the formation of presynaptic terminals, whereas the disease-associated mutations result in a loss of this synaptic function. Our findings suggest that the previously identified mutations in neuroligin genes are likely to be relevant for the neuro-developmental defects in autism-spectrum disorders and mental retardation since they impair the function of a synaptic cell adhesion molecule.
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PMID:Disorder-associated mutations lead to functional inactivation of neuroligins. 1515 Jan 61

An Australian patient with autism was found to be heterozygous for two mutations in the gene encoding adenylosuccinate lyase (ASL), resulting in the protein mutations E80D and D87E. The patient's mother carried only the E80D mutation. The equivalent positions are 62 and 69 in Bacillus subtilis ASL. Although both human and B. subtilis enzymes normally have Asp at position 87 (or 69), the B. subtilis ASL has Ile and Asp at 62 and 65, respectively, whereas human ASL has Glu and Arg at the equivalent positions. We have constructed, expressed, and purified the double mutant I62E/D65R as a "humanized" normal B. subtilis enzyme to compare with enzymes with a single mutation at position 62 (I62D/D65R), at position 69 (I62E/D65R/D69E), or at both positions (I62D/D65R/D69E). V(max) for conversion of adenylosuccinate to AMP and fumarate is 0.57 micromol/min/mg for I62E/D65R, 0.064 micromol/min/mg for I62D/D65R, 0.27 micromol/min/mg for I62E/D65R/D69E, and 0.069 micromol/min/mg for I62D/D65R/D69E. The K(m) for adenylosuccinate is elevated in the X62D mutants, and I62D/D65R is the least stable of these ASLs at 37 degrees C. The CD spectra of mutant and wild type enzymes are similar; thus, there are no appreciable structural changes. Clearly the Asp(62) causes the most drastic effect on ASL function, whereas the Glu(69) mutation produces only modest change. These results emphasize the importance of expanding tests for ASL deficiency to individuals with developmental delay of any severity, including individuals with autistic spectrum disorder. This study further demonstrates the usefulness of the B. subtilis ASL as a model to mimic the defective enzyme in ASL deficiency.
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PMID:Two novel mutant human adenylosuccinate lyases (ASLs) associated with autism and characterization of the equivalent mutant Bacillus subtilis ASL. 1547 76

Autism is a highly heritable neurodevelopmental syndrome with a complex genetic etiology for which no disease genes have yet been definitively identified. We ascertained three subjects with autism spectrum disorders and chromosome 2q37.3 terminal deletions, and refined the deletion breakpoint regions using polymorphism mapping and fluorescence in situ hybridization (FISH) probes. We then genotyped polymorphic markers downstream from the breakpoint region in a sample of autism affected sibling pair families. Both the chromosomal breakpoints and linkage analyses focused our attention on the gene centaurin gamma-2 (CENTG2), an attractive candidate gene based also on its function and pattern of expression. We therefore assessed CENTG2 for its involvement in autism by (1) screening its exons for variants in 199 autistic and 160 non-autistic individuals, and (2) genotyping and assessing intra-genic polymorphisms for linkage and linkage disequilibrium (LD). The exon screen revealed a Ser --> Gly substitution in one proband, an Arg --> Gly substitution in another, and a number of additional variants unique to the autism families. No unique variants were found in the control subjects. The genotyping produced strong evidence for linkage from two intronic polymorphisms, with a maximum two-point HLOD value of 3.96 and a posterior probability of linkage (PPL) of 51%. These results were contradicted, however, by substantially weaker evidence for linkage from multi-point analyses and by no evidence of LD. We conclude, therefore, that 2q37.3 continues to be a region of interest for autism susceptibility, and that CENTG2 is an intriguing candidate gene that merits further scrutiny for its role in autism.
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PMID:Evaluation of the chromosome 2q37.3 gene CENTG2 as an autism susceptibility gene. 1589 43

An Arg to Cys mutation in the extracellular domain of neuroligin-3 (NL3) was recently found in a twin set with autism [S. Jamain, H. Quach, C. Betancur, M. Rastam, C. Colineaux, I.C. Gillberg, H. Soderstrom, B. Giros, M. Leboyer, C. Gillberg, T. Bourgeron, Paris Autism Research International Sibpair Study, mutations of the X-linked genes encoding neuroligins NLGN3 and NLGN4 are associated with autism, Nat. Genet. 34 (2003) 27-29]. The Cys substitution in NL3 causes altered intracellular protein trafficking, intracellular retention and diminished association with its cognate partner, beta-neurexin [D. Comoletti, A. De Jaco, L.L. Jennings, R.E. Flynn, G. Gaietta, I. Tsigelny, M.H. Ellisman, P. Taylor, The R451C-neuroligin-3 mutation associated with autism reveals a defect in protein processing, J. Neurosci. 24 (2004) 4889-4893]. NL3, butyrylcholinesterase (BuChE), and acetylcholinesterase (AChE), as members of the (/(-hydrolase fold family of proteins, share over 30% of amino acid identity in their extracellular domains. In particular, Arg451 in NL3 is conserved in the alpha/beta-hydrolase fold family being homologous to Arg386 in BuChE and Arg395 in AChE. A Cys substitution at the homologous Arg in the BuChE was found studying post-succinylcholine apnea in an Australian population [T. Yen, B.N. Nightingale, J.C. Burns, D.R. Sullivan, P.M. Stewart, Butyrylcholinesterase (BCHE) genotyping for post-succinylcholine apnea in an Australian population, Clin. Chem. 49 (2003) 1297-308]. We have made the homologous mutation in the mouse AChE and BuChE genes and showed that the Arg to Cys mutations resulted in identical alterations in the cellular phenotype for the various members of the alpha/beta-hydrolase fold family proteins.
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PMID:A single mutation near the C-terminus in alpha/beta hydrolase fold protein family causes a defect in protein processing. 1642 95

We describe a nondysmorphic patient with developmental delay and autism spectrum disorder who has a missense mutation in the Jumonji AT-rich interactive domain 1C (JARID1C) gene. This child first presented at 30 months of age with stereotyped and repetitive behaviors, impairment in social reciprocity and in the use of multiple nonverbal behaviors, and developmental delay primarily in the language domain. A diagnosis of autism was made and subsequently confirmed at the current age of 47 months. Cytogenetic and fragile X studies were normal. Mutational analysis revealed a novel missense mutation in exon 16 of the JARID1C gene that results in an arginine to tryptophan substitution at amino acid 766 (R766W). Sequence alignment analysis with multiple available eukaryotic sequences including the homologous proteins of mouse and zebrafish demonstrated that the affected amino acid is conserved. JARID1C has not previously been implicated in autism susceptibility. Recent novel molecular evidence suggests that it is a histone demethylase specific for di- and trimethylated histone 3 lysine 4 (H3K4) and functions as a transcriptional repressor by fostering REST-mediated neuronal gene regulation. The JARID1C-regulated genes SCN2A, CACNA1H, BDNF, and SLC18A1 have previously been associated with autism and cognitive dysfunction. This patient brings the total number of reported JARID1C mutations to 14. This presentation both extends the range of neurocognitive phenotypes attributable to mutations in this gene and illustrates the importance of molecular studies and DNA sequence analysis for accurate diagnosis of monogenic causes of autism.
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PMID:A novel mutation in JARID1C/SMCX in a patient with autism spectrum disorder (ASD). 1820 67

The human serotonin (5-hydroxytryptamine, 5-HT) transporter (hSERT, SLC6A4) figures prominently in the etiology and treatment of many prevalent neurobehavioral disorders including anxiety, alcoholism, depression, autism, and obsessive-compulsive disorder (OCD). Here, we use naturally occurring polymorphisms in recombinant inbred (RI) lines to identify multiple phenotypes associated with altered SERT function. The widely used mouse strain C57BL/6J, harbors a SERT haplotype defined by 2 nonsynonymous coding variants [Gly-39 and Lys-152 (GK)]. At these positions, many other mouse lines, including DBA/2J, encode, respectively, Glu-39 and Arg-152 (ER haplotype), amino acids found also in hSERT. Ex vivo synaptosomal 5-HT transport studies revealed reduced uptake associated with the GK variant, a finding confirmed by in vitro heterologous expression studies. Experimental and in silico approaches using RI lines (C57BL/6J x DBA/2J = BXD) identify multiple anatomical, biochemical, and behavioral phenotypes specifically impacted by GK/ER variation. Among our findings are several traits associated with alcohol consumption and multiple traits associated with dopamine signaling. Further bioinformatic analysis of BXD phenotypes, combined with biochemical evaluation of SERT knockout mice, nominates SERT-dependent 5-HT signaling as a major determinant of midbrain iron homeostasis that, in turn, dictates iron-regulated DA phenotypes. Our studies provide an example of the power of coordinated in vitro, in vivo, and in silico approaches using mouse RI lines to elucidate and quantify the system-level impact of gene variation.
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PMID:Functional coding variation in recombinant inbred mouse lines reveals multiple serotonin transporter-associated phenotypes. 1917 83

Proteins of the alpha/beta-hydrolase fold family share a common structural fold, but perform a diverse set of functions. We have been studying natural mutations occurring in association with congenital disorders in the alpha/beta-hydrolase fold domain of neuroligin (NLGN), butyrylcholinesterase (BChE), acetylcholinesterase (AChE). Starting from the autism-related R451C mutation in the alpha/beta-hydrolase fold domain of NLGN3, we had previously shown that the Arg to Cys substitution is responsible for endoplasmic reticulum (ER) retention of the mutant protein and that a similar trafficking defect is observed when the mutation is inserted at the homologous positions in AChE and BChE. Herein we show further characterization of the R451C mutation in NLGN3 when expressed in HEK-293, and by protease digestion sensitivity, we reveal that the phenotype results from protein misfolding. However, the presence of an extra Cys does not interfere with the formation of disulfide bonds as shown by reaction with PEG-maleimide and estimation of the molecular mass changes. These findings highlight the role of proper protein folding in protein processing and localization.
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PMID:Folding anomalies of neuroligin3 caused by a mutation in the alpha/beta-hydrolase fold domain. 2022 2

The neurobiological basis of autism spectrum disorder (ASD) remains poorly understood. Given the role of CD38 in social recognition through oxytocin (OT) release, we hypothesized that CD38 may play a role in the etiology of ASD. Here, we first examined the immunohistochemical expression of CD38 in the hypothalamus of post-mortem brains of non-ASD subjects and found that CD38 was colocalized with OT in secretory neurons. In studies of the association between CD38 and autism, we analyzed 10 single nucleotide polymorphisms (SNPs) and mutations of CD38 by re-sequencing DNAs mainly from a case-control study in Japan, and Caucasian cases mainly recruited to the Autism Genetic Resource Exchange (AGRE). The SNPs of CD38, rs6449197 (p<0.040) and rs3796863 (p<0.005) showed significant associations with a subset of ASD (IQ>70; designated as high-functioning autism (HFA)) in the U.S. 104 AGRE family trios, but not with Japanese 188 HFA subjects. A mutation that caused tryptophan to replace arginine at amino acid residue 140 (R140W; (rs1800561, 4693C>T)) was found in 0.6-4.6% of the Japanese population and was associated with ASD in the smaller case-control study. The SNP was clustered in pedigrees in which the fathers and brothers of T-allele-carrier probands had ASD or ASD traits. In this cohort OT plasma levels were lower in subjects with the T allele than in those without. One proband with the T allele who was taking nasal OT spray showed relief of symptoms. The two variant CD38 poloymorphysms tested may be of interest with regard of the pathophysiology of ASD.
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PMID:Two genetic variants of CD38 in subjects with autism spectrum disorder and controls. 2043 66


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