2,397 research outputs found

    Autism genetics: searching for specificity and convergence.

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    Advances in genetics and genomics have improved our understanding of autism spectrum disorders. As many genes have been implicated, we look to points of convergence among these genes across biological systems to better understand and treat these disorders

    Autism: Many Genes, Common Pathways?

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    Autism is a heterogeneous neurodevelopmental syndrome with a complex genetic etiology. It is still not clear whether autism comprises a vast collection of different disorders akin to intellectual disability or a few disorders sharing common aberrant pathways. Unifying principles among cases of autism are likely to be at the level of brain circuitry in addition to molecular pathways

    The Autism Related Protein Contactin-Associated Protein-Like 2 (CNTNAP2) Stabilizes New Spines: An In Vivo Mouse Study.

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    The establishment and maintenance of neuronal circuits depends on tight regulation of synaptic contacts. We hypothesized that CNTNAP2, a protein associated with autism, would play a key role in this process. Indeed, we found that new dendritic spines in mice lacking CNTNAP2 were formed at normal rates, but failed to stabilize. Notably, rates of spine elimination were unaltered, suggesting a specific role for CNTNAP2 in stabilizing new synaptic circuitry

    Schizophrenia: Genome, Interrupted

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    Structural chromosomal variation is increasingly recognized as an important contributor to human diseases, particularly those of neurodevelopment, such as autism. A current paper makes a significant advance to schizophrenia genetics by establishing an association with rare copy number variants (CNV), which are over-represented in neurodevelopmental genes

    Replication of linkage at chromosome 20p13 and identification of suggestive sex-differential risk loci for autism spectrum disorder.

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    BackgroundAutism spectrum disorders (ASDs) are male-biased and genetically heterogeneous. While sequencing of sporadic cases has identified de novo risk variants, the heritable genetic contribution and mechanisms driving the male bias are less understood. Here, we aimed to identify familial and sex-differential risk loci in the largest available, uniformly ascertained, densely genotyped sample of multiplex ASD families from the Autism Genetics Resource Exchange (AGRE), and to compare results with earlier findings from AGRE.MethodsFrom a total sample of 1,008 multiplex families, we performed genome-wide, non-parametric linkage analysis in a discovery sample of 847 families, and separately on subsets of families with only male, affected children (male-only, MO) or with at least one female, affected child (female-containing, FC). Loci showing evidence for suggestive linkage (logarithm of odds ≥2.2) in this discovery sample, or in previous AGRE samples, were re-evaluated in an extension study utilizing all 1,008 available families. For regions with genome-wide significant linkage signal in the discovery stage, those families not included in the corresponding discovery sample were then evaluated for independent replication of linkage. Association testing of common single nucleotide polymorphisms (SNPs) was also performed within suggestive linkage regions.ResultsWe observed an independent replication of previously observed linkage at chromosome 20p13 (P < 0.01), while loci at 6q27 and 8q13.2 showed suggestive linkage in our extended sample. Suggestive sex-differential linkage was observed at 1p31.3 (MO), 8p21.2 (FC), and 8p12 (FC) in our discovery sample, and the MO signal at 1p31.3 was supported in our expanded sample. No sex-differential signals met replication criteria, and no common SNPs were significantly associated with ASD within any identified linkage regions.ConclusionsWith few exceptions, analyses of subsets of families from the AGRE cohort identify different risk loci, consistent with extreme locus heterogeneity in ASD. Large samples appear to yield more consistent results, and sex-stratified analyses facilitate the identification of sex-differential risk loci, suggesting that linkage analyses in large cohorts are useful for identifying heritable risk loci. Additional work, such as targeted re-sequencing, is needed to identify the specific variants within these loci that are responsible for increasing ASD risk

    Representational differences in how students compare measurements

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    Measurement uncertainty plays a critical role in the process of experimental physics. It is useful to be able to assess student proficiency around the topic to iteratively improve instruction and student learning. For the topic of measurement uncertainty, we developed an assessment tool called the Survey of Physics Reasoning on Uncertainty Concepts in Experiments (SPRUCE), which aims to assess students' knowledge, and use of, a variety of concepts related to measurement uncertainty. This assessment includes two isomorphic questions focused on comparing two measurements with uncertainty. One is presented numerically and the other pictorially. Despite the questions probing identical concepts, students answer them in different ways, indicating that they rely on distinct modes of representation to make sense of measurement uncertainty and comparisons. Specifically, students score much higher on the pictorially represented item, which suggests possible instructional changes to leverage students' use of representations while working with concepts of measurement uncertainty.Comment: 4 pages, 2 figures, to be published in PERC Conference Proceedings 202

    Eu0.5_{0.5}Sr1.5_{1.5}MnO4_4: a three-dimensional XY spin glass

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    The frequency, temperature, and dc-bias dependence of the ac-susceptibility of a high quality single crystal of the Eu0.5_{0.5}Sr1.5_{1.5}MnO4_4 layered manganite is investigated. Eu0.5_{0.5}Sr1.5_{1.5}MnO4_4 behaves like a XY spin glass with a strong basal anisotropy. Dynamical and static scalings reveal a three-dimensional phase transition near TgT_g = 18 K, and yield critical exponent values between those of Heisenberg- and Ising-like systems, albeit slightly closer to the Ising case. Interestingly, as in the latter system, the here observed rejuvenation effects are rather weak. The origin and nature of the low temperature XY spin glass state is discussed.Comment: REVTeX 4 style; 5 pages, 4 figure
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