Variants in adjacent oxytocin/vasopressin gene region and associations with ASD diagnosis and autism related endophenotypes
Contributors: Cook, Edwin H., Francis, Sunday M., Kistner-Griffin, Emily, Yan, Zhongyu, Guter, Stephen, Jacob, Suma
... Abstract Background: There has been increasing interest in oxytocin (peptide: OT, gene: OXT) as a treatment pathway for neurodevelopmental disorders such as Autism Spectrum Disorder (ASD). Neurodevelopmental disorders affect functional, social, and intellectual abilities. With advances in molecular biology, research has connected multiple gene regions to the clinical presentation of ASD. Studies have also shown that the neuropeptide hormones OT and arginine vasopressin (AVP) influence mammalian social and territorial behaviors and may have treatment potential for neurodevelopmental disorders. Published data examining molecular and phenotypic variation in ASD, such as cognitive abilities, are limited. Since most studies have focused on the receptors in the OT-AVP system, we investigated genetic variation within peptide genes for association with phenotypic ASD features that help identify subgroups within the spectrum. Methods: In this study, TDT analysis was carried out utilizing FBAT in 207 probands (156 trios) and a European Ancestry (EA) subsample (108 trios). The evolutionarily related and adjacent genes of OXT and AVP were studied for associations between the tagged single nucleotide polymorphisms and ASD diagnosis, social abilities, restrictive and repetitive behaviors, and IQ for cognitive abilities. Additionally, relationships with whole blood serotonin (WB5HT) were explored because of the developmental relationships connecting plasma levels of OT and WB5HT within ASD. Results: Results indicate significant association between OXT rs6084258 (p=0.001) and ASD. Associations with several intermediate phenotypes were also noted: OXT rs6133010 was associated with IQ (full scale IQ, p=0.008; nonverbal IQ, p=0.009, verbal IQ, p=0.006); and OXT rs6084258 and OXT rs877172 were associated with WB5HT levels (EA, p=0.029 and p=0.050, respectively). Additionally, we measured plasma OT (pOT) levels in a subsample (N=54). Results show the same two polymorphisms, OXT rs877172 and OXT rs6084258, have significant association with pOT (EA, p=0.002 and p=0.011, respectively). Conclusions: These findings suggest that SNPs near OXT and AVP are associated with diagnosis of ASD, social behaviors, restricted and repetitive behaviors, IQ, pOT, and WB5HT. Future studies need to replicate these findings and examine gene-interactions in other neurodevelopmental disorders. Mechanisms of action may influence early social and cognitive development that may or may not be limited to ASD diagnosis.
Autonomy of lower-level perception from global processing in autism: evidence from brain activation and functional connectivity.
Contributors: Liu, Y, Cherkassky, V, Minshew, N, Just, M
... Abstract Previous behavioral studies have shown that individuals with autism are less hindered by interference from global processing during the performance of lower-level perceptual tasks, such as finding embedded figures. The primary goal of this study was to examine the brain manifestation of such atypicality in high-functioning autism using fMRI. Fifteen participants with high-functioning autism and fifteen age- and IQ-matched typical controls were asked to perform a lower-level perceptual line-counting task in the presence of a distracting depiction of a 3-D object, in which participants counted whether there were more red or more green contours (In a contrasting 3-D task, participants judged whether the same 3-D stimulus objects (but without color in any contours) depicted a possible or impossible 3-D object). We hypothesized that individuals with autism would be less likely than controls to process the global 3-D information (and would hence show fewer neural signs of such interfering 3-D processing) during the lower-level line-counting task. The fMRI results revealed that in the line-counting task, the autism group did not show the increased medial frontal activity (relative to the possibility task), or the increased functional connectivity between the medial frontal region and posterior visual-spatial regions, demonstrated by the control group. Both findings are indices of lesser effort and difficulty in the line-counting task for the autism group than for the control group, attributed to less interference from the 3-D processing in the autism group. In addition, in the line-counting task, the control group showed a positive correlation between a measure of spatial ability (Vandenberg scores) and activation in the medial frontal region, suggesting that more spatially able control participants did more suppression of the irrelevant 3-D background information in order to focus on the line-counting task. The findings collectively indicate that the global 3-D structure of the figure had a smaller effect, if any, on local processing in the group with autism compared to the control group. The results from this study provide the first direct neural evidence of reduced global-to-local interference in autism.
Genotypes of Swedish subjects used in "Most genetic risk for autism resides with common variation" study
Contributors: Buxbaum, JD, Gaugler, T, Klei, L, Sanders, SJ, Bodea, CA, Goldberg, AP, Lee, AB, Mahajan, M, Manaa, D, Pawitan, Y
... Abstract A key component of genetic architecture is the allelic spectrum influencing trait variability. For autism spectrum disorder (herein termed autism), the nature of the allelic spectrum is uncertain. Individual risk-associated genes have been identified from rare variation, especially de novo mutations. From this evidence, one might conclude that rare variation dominates the allelic spectrum in autism, yet recent studies show that common variation, individually of small effect, has substantial impact en masse. At issue is how much of an impact relative to rare variation this common variation has. Using a unique epidemiological sample from Sweden, new methods that distinguish total narrow-sense heritability from that due to common variation and synthesis of results from other studies, we reach several conclusions about autism's genetic architecture: its narrow-sense heritability is ~52.4%, with most due to common variation, and rare de novo mutations contribute substantially to individual liability, yet their contribution to variance in liability, 2.6%, is modest compared to that for heritable variation.
Contributors: James, F. Gusella, Migliavacca, E, Golzio, C, Männik, K, Blumenthal, I, Oh, EC, Harewood, L, Kosmicki, JA, Loviglio, MN, Giannuzzi, G
... Abstract The 16p11.2 600 kb copy-number variants (CNVs) are associated with mirror phenotypes on BMI, head circumference, and brain volume and represent frequent genetic lesions in autism spectrum disorders (ASDs) and schizophrenia. Here we interrogated the transcriptome of individuals carrying reciprocal 16p11.2 CNVs. Transcript perturbations correlated with clinical endophenotypes and were enriched for genes associated with ASDs, abnormalities of head size, and ciliopathies. Ciliary gene expression was also perturbed in orthologous mouse models, raising the possibility that ciliary dysfunction contributes to 16p11.2 pathologies. In support of this hypothesis, we found structural ciliary defects in the CA1 hippocampal region of 16p11.2 duplication mice. Moreover, by using an established zebrafish model, we show genetic interaction between KCTD13, a key driver of the mirrored neuroanatomical phenotypes of the 16p11.2 CNV, and ciliopathy-associated genes. Overexpression of BBS7 rescues head size and neuroanatomical defects of kctd13 morphants, whereas suppression or overexpression of CEP290 rescues phenotypes induced by KCTD13 under- or overexpression, respectively. Our data suggest that dysregulation of ciliopathy genes contributes to the clinical phenotypes of these CNVs.
Contributors: Doyle, AE, Brand, H, Pillalamarri, V, Collins, R, Eggert, S, O'Dushlaine, C, Braaten, EB, Stone, M, Chambert, K, Doty, ND
... Abstract Structural variation (SV) is a significant component of the genetic etiology of both neurodevelopmental and psychiatric disorders; however, routine guidelines for clinical genetic screening have been established only in the former category. Genome-wide chromosomal microarray (CMA) can detect genomic imbalances such as copy-number variants (CNVs), but balanced chromosomal abnormalities (BCAs) still require karyotyping for clinical detection. Moreover, submicroscopic BCAs and subarray threshold CNVs are intractable, or cryptic, to both CMA and karyotyping. Here, we performed whole-genome sequencing using large-insert jumping libraries to delineate both cytogenetically visible and cryptic SVs in a single test among 30 clinically referred youth representing a range of severe neuropsychiatric conditions. We detected 96 SVs per person on average that passed filtering criteria above our highest-confidence resolution (6,305 bp) and an additional 111 SVs per genome below this resolution. These SVs rearranged 3.8 Mb of genomic sequence and resulted in 42 putative loss-of-function (LoF) or gain-of-function mutations per person.We estimate that 80% of the LoF variants were cryptic to clinical CMA. We found myriad complex and cryptic rearrangements, including a "paired" duplication (360 kb, 169 kb) that flanks a 5.25 Mb inversion that appears in 7 additional cases from clinical CNV data among 47,562 individuals. Following convergent genomic profiling of these independent clinical CNV data, we interpreted three SVs to be of potential clinical significance. These data indicate that sequence-based delineation of the full SV mutational spectrum warrants exploration in youth referred for neuropsychiatric evaluation and clinical diagnostic SV screening more broadly.
Psychometric Analysis of the Social Communication Questionnaire Using an Item-Response Theory Framework: Implications for the Use of the Lifetime and Current Forms
Contributors: Wei, T, Chesnut, SR, Barnard-Brak, L, Richman, DM
... Abstract NDAR Study for new article accepted for publication in Journal of Psychopathology and Behavioral Assessment.
Contributors: Volk, HE, Kerin, T, Lurmann, F, Hertz-Picciotto, I, McConnell, R, Campbell, DB
... Abstract Background: Independent studies report association of autism spectrum disorder with air pollution exposure and a functional promoter variant (rs1858830) in the MET receptor tyrosine kinase (MET) gene. Toxicologic data find altered brain Met expression in mice after prenatal exposure to a model air pollutant. Our objective was to investigate whether air pollution exposure and MET rs1858830 genotype interact to alter ASD risk. Methods: We studied 252 cases of autism spectrum disorder and 156 typically developing controls the Childhood Autism Risk from Genetics and the Environment Study. Air pollution exposure was assigned for local traffic-related sources and regional sources (particulate matter, nitrogen dioxide and ozone). MET genotype was determined by direct re-sequencing. Results: Subjects with both MET rs1858830 CC genotype and high air pollutant exposures were at increased risk of autism spectrum disorder compared with subjects who had both the CG/GG genotypes and lower pollutant exposures. A statistical test of multiplicative interaction identified a statistically significant effect between NO2 and MET CC genotype (p=0.03) Conclusions: MET rs1858830 CC genotype and air pollutant exposure may interact to increase autism spectrum disorder risk.
Contributors: Menon, Vinod, Superkar, K, Uddin, LQ, Khouzam, A, Phillips, J, Gaillard, WD, Kenworthy, LE, Yerys, BE, Vaidya, CJ
... Abstract Autism spectrum disorder (ASD), a neurodevelopmental disorder affecting nearly 1 in 88 children, is thought to result from aberrant brain connectivity. Remarkably, there have been no systematic attempts to characterize whole-brain connectivity in children with ASD. Here, we use neuroimaging to show that there are more instances of greater functional connectivity in the brains of children with ASD in comparison to those of typically developing children. Hyperconnectivity in ASD was observed at the whole-brain and subsystems levels, across long- and short-range connections, and was associated with higher levels of fluctuations in regional brain signals. Brain hyperconnectivity predicted symptom severity in ASD, such that children with greater functional connectivity exhibited more severe social deficits. We replicated these findings in two additional independent cohorts, demonstrating again that at earlier ages, the brain of children with ASD is largely functionally hyperconnected in ways that contribute to social dysfunction. Our findings provide unique insights into brain mechanisms underlying childhood autism.
The National Database for Autism Research: Quality Assurance Metrics for the Structural Neuroimaging Data
Contributors: Kennedy, D, Haselgrove, C
... Abstract A draft publication is in progress.
Transcriptional consequences of 16p11.2 deletion and duplication in mouse cortex and multiplex autism families
Contributors: Gusella, JF, Blumenthal, I, Ragavendran, A, Erdin, S, Klei, L, Sugathan, A, Guide, JR, Manavalan, P, Zhou, JQ, Wheeler, VC
... Abstract Publication Abstract: Reciprocal copy number variation (CNV) of a 593 kb region of 16p11.2 is a common genetic cause of autism spectrum disorder (ASD), yet it is not completely penetrant and can manifest in a wide array of phenotypes. To explore its molecular consequences, we performed RNA-sequencing of cerebral cortex from mouse models with CNV of the syntenic 7qF3 region, and lymphoblast lines from 34 members of seven multiplex ASD families harboring the 16p11.2 CNV. Expression of all genes in the CNV region correlated well with their DNA copy number, with no evidence of dosage compensation. We observed effects on gene expression outside the CNV region, including apparent positional effects in cis and in trans at genomic segments with evidence of physical interaction in Hi-C chromosome conformation data. One of the most significant positional effects was telomeric to the 16p11.2 CNV and includes the previously described 'distal' 16p11.2 microdeletion. Overall, 16p11.2 CNV was associated with altered expression of genes and networks that converge on multiple hypotheses of ASD pathogenesis, including synaptic function (e.g., NRXN1, NRXN3), chromatin modification (e.g., CHD8, EHMT1, MECP2), transcriptional regulation (e.g.,TCF4, SATB2), and intellectual disability (e.g., FMR1, CEP290). However, there were differences between tissues and species, with the strongest effects being consistently within the CNV region itself. Our analyses suggest that through a combination of indirect regulatory effects and direct effects on nuclear architecture, alteration of 16p11.2 genes disrupts expression networks that involve other genes and pathways known to contribute to ASD, suggesting an overlap in mechanisms of pathogenesis.