Search

Your search keyword '"DeFries, John C."' showing total 728 results
Start Over Author "DeFries, John C."
728 results on '"DeFries, John C."'

151. Quantitative Trait Locus Mapping in Laboratory Mice Derived From a Replicated Selection Experiment for Open-Field Activity

Author

Turri, Maria Grazia, Henderson, Norman D., DeFries, John C., and Flint, Jonathan

Subjects
Genetic research -- Analysis, Human behavior -- Genetic aspects, Rodents -- Genetic aspects, Biological sciences
Abstract

Bidirectional selection in rodents has been used to derive animal models of human behavior. An important question is whether selection for behavior operates on a limited number of QTL or whether the number and individual contribution of QTL varies between selection experiments. To address this question, we mapped QTL in two large [F.sub.2] intercrosses (N = 815 and 821) from the four lines derived from a replicated selection experiment for open-field activity, an animal model for susceptibility to anxiety. Our analyses indicate that selection operated on the same relatively small number of loci in both crosses. Haplotype information and the direction of effect of each QTL allele were used to confirm that the QTL mapped in the two crosses lie in the same chromosomal regions, although we were unable to determine whether QTL in the two crosses represent the same genes. We conclude that the genetic architecture of the selected strains is similar and relatively simple.

Published
2001

153. A Twin MRI Study of Size Variations in the Human Brain

Author

Pennington, Bruce F., Filipek, Pauline A., Lefly, Dianne, Chhabildas, Nomita, Kennedy, David N., Simon, Jack H., Filley, Christopher M., Galaburda, Albert, and DeFries, John C.

Subjects
Human anatomy -- Usage, Magnetic resonance imaging -- Usage, Brain -- Size, Variation (Biology) -- Usage, Health, Psychology and mental health, Usage
Abstract

Abstract * Although it is well known that there is considerable variation among individuals in the size of the human brain, the etiology of less extreme individual differences in brain [...]

Published
2000

156. Genome-wide screening for DNA variants associated with reading and language traits

Author

Gialluisi, Alessandro, Newbury, Dianne F, Wilcutt, Erik G, Olson, Richard K, DeFries, John C, Brandler, William M, Pennington, Bruce F, Smith, Shelley D, Scerri, Thomas S, Simpson, Nuala H, The SLI Consortium, Luciano, Michelle, Evans, David M, Bates, Timothy C, Stein, John F, Talcott, Joel B, Monaco, Anthony P, Paracchini, Silvia, Francks, Clyde, Fisher, Simon E, University of St Andrews. School of Medicine, and University of St Andrews. Biomedical Sciences Research Complex

Subjects
Neuroinformatics, Male, CLDRC, BF Psychology, Adolescent, SLIC, Developmental dyslexia, Pleiotropic variants, BF, QH426 Genetics, Polymorphism, Single Nucleotide, Dyslexia, reading, GWAS, Humans, Child, QH426, Language, language, Language Tests, Genome, Human, reading disability, RNA-Binding Proteins, Genetic Pleiotropy, Original Articles, pleiotropic variants, developmental dyslexia, Neoplasm Proteins, meta-analysis, Repressor Proteins, Meta-analysis, specific language impairment, Reading, Specific language impairment, Case-Control Studies, Female, Reading disability, RNA Splicing Factors, BDC, Genome-Wide Association Study
Abstract

This research was funded by: Max Planck Society, the University of St Andrews - Grant Number: 018696, US National Institutes of Health - Grant Number: P50 HD027802, Wellcome Trust - Grant Number: 090532/Z/09/Z, and Medical Research Council Hub Grant Grant Number: G0900747 91070 Reading and language abilities are heritable traits that are likely to share some genetic influences with each other. To identify pleiotropic genetic variants affecting these traits, we first performed a genome‐wide association scan (GWAS) meta‐analysis using three richly characterized datasets comprising individuals with histories of reading or language problems, and their siblings. GWAS was performed in a total of 1862 participants using the first principal component computed from several quantitative measures of reading‐ and language‐related abilities, both before and after adjustment for performance IQ. We identified novel suggestive associations at the SNPs rs59197085 and rs5995177 (uncorrected P ≈ 10–7 for each SNP), located respectively at the CCDC136/FLNC and RBFOX2 genes. Each of these SNPs then showed evidence for effects across multiple reading and language traits in univariate association testing against the individual traits. FLNC encodes a structural protein involved in cytoskeleton remodelling, while RBFOX2 is an important regulator of alternative splicing in neurons. The CCDC136/FLNC locus showed association with a comparable reading/language measure in an independent sample of 6434 participants from the general population, although involving distinct alleles of the associated SNP. Our datasets will form an important part of on‐going international efforts to identify genes contributing to reading and language skills. Publisher PDF

Published
2014

162. Identification of candidate genes for dyslexia susceptibility on chromosome 18

Author

Scerri, Thomas S., Paracchini, Silvia, Morris, Andrew, MacPhie, I. Laurence, Talcott, Joel B., Stein, John F., Smith, Shelley D., Pennington, Bruce F., Olson, Richard K., DeFries, John C., Monaco, Anthony P., and Richardson, Alex J.

Abstract

Six independent studies have identified linkage to chromosome 18 for developmental dyslexia or general reading ability. Until now, no candidate genes have been identified to explain this linkage. Here, we set out to identify the gene(s) conferring susceptibility by a two stage strategy of linkage and association analysis. Methodology/Principal Findings: Linkage analysis: 264 UK families and 155 US families each containing at least one child diagnosed with dyslexia were genotyped with a dense set of microsatellite markers on chromosome 18. Association analysis: Using a discovery sample of 187 UK families, nearly 3000 SNPs were genotyped across the chromosome 18 dyslexia susceptibility candidate region. Following association analysis, the top ranking SNPs were then genotyped in the remaining samples. The linkage analysis revealed a broad signal that spans approximately 40 Mb from 18p11.2 to 18q12.2. Following the association analysis and subsequent replication attempts, we observed consistent association with the same SNPs in three genes; melanocortin 5 receptor (MC5R), dymeclin (DYM) and neural precursor cell expressed, developmentally down-regulated 4-like (NEDD4L). Conclusions: Along with already published biological evidence, MC5R, DYM and NEDD4L make attractive candidates for dyslexia susceptibility genes. However, further replication and functional studies are still required.

Published
2010

163. Testing for Neuropsychological Endophenotypes in Siblings Discordant for ADHD

Author

Bidwell, L. Cinnamon, Willcutt, Erik G., DeFries, John C., and Pennington, Bruce F.

Subjects
Intelligence Tests, Male, Analysis of Variance, Adolescent, Twins, Neuropsychological Tests, Article, Phenotype, Sex Factors, Reading, Attention Deficit Disorder with Hyperactivity, Diseases in Twins, Humans, Female, Genetic Predisposition to Disease, Child, Cognition Disorders, Problem Solving
Abstract

Neurocognitive deficits associated with attention-deficit/hyperactivity disorder (ADHD) might be useful intermediate endophenotypes for determining specific genetic pathways that contribute to ADHD.This study administered 17 measures from prominent neuropsychological theories of ADHD (executive function, processing speed, arousal regulation and, motivation/delay aversion) in dizygotic (DZ) twin pairs discordant for ADHD and control twin pairs (ages 8-18 years) to compare performance between twins affected with ADHD (n = 266), their unaffected co-twins (n = 228), and control children from twin pairs without ADHD or learning difficulties (n = 332).The ADHD subjects show significant impairment on executive function, processing speed, and response variability measures compared with control subjects. Unaffected co-twins of ADHD subjects are significantly impaired on nearly all the same measures as their ADHD siblings, even when subclinical symptoms of ADHD are controlled.Executive function, processing speed, and response variability deficits might be useful endophenotypes for genetic studies of ADHD.

Published
2007

167. Genetic and Environmental Influences on Vocabulary and Reading Development

Author

Olson, Richard, Keenan, Janice M, Byrne, Brian, Samuelsson, Stefan, Coventry, William L, Corley, Robin, Wadsworth, Sally J, Willcutt, Erik G, DeFries, John C, Pennington, Bruce F, Olson, Richard, Keenan, Janice M, Byrne, Brian, Samuelsson, Stefan, Coventry, William L, Corley, Robin, Wadsworth, Sally J, Willcutt, Erik G, DeFries, John C, and Pennington, Bruce F

Abstract

Genetic and environmental relations between vocabulary and reading skills were explored longitudinally from preschool through Grades 2 and 4. At preschool there were strong shared-environment and weak genetic influences on both vocabulary and print knowledge but substantial differences in their source. Separation of etiology for vocabulary and reading continued for word recognition and decoding through Grade 4, but genetic and environmental correlations between vocabulary and reading comprehension approached unity by Grade 4, when vocabulary and word recognition accounted for all of the genetic and shared environment influences on reading comprehension.

Published
2011
Full Text
View/download PDF

168. Response to early literacy instruction in the United States, Australia, and Scandinavia : A behavioral-genetic analysis

Author

Samuelsson, Stefan, Byrne, Brian, Olson, Richard K., Hulslander, Jacqueline, Wadsworth, Sally, Corley, Robin, Willcutt, Erik G., DeFries, John C., Samuelsson, Stefan, Byrne, Brian, Olson, Richard K., Hulslander, Jacqueline, Wadsworth, Sally, Corley, Robin, Willcutt, Erik G., and DeFries, John C.

Abstract

Genetic and environmental influences on early reading and spelling at the end of kindergarten and Grade 1 were compared across three twin samples tested in the United States, Australia, and Scandinavia. Proportions of variance due to genetic influences on kindergarten reading were estimated at .84 in Australia, .68 in the U.S., and .33 in Scandinavia. The effects of shared environment on kindergarten reading were estimated at .09 in Australia, .25 in the U.S., and .52 in Scandinavia. A similar pattern of genetic and environmental influences was obtained for kindergarten spelling. One year later when twins in all three samples had received formal literacy instruction for at least one full school year, heritability was similarly high across country, with estimated genetic influences varying between .79 and .83 for reading and between .62 and .79 for spelling. These findings indicate that the pattern of genetic and environmental influences on early reading and spelling development varies according to educational context, with genetic influence increasing as a function of increasing intensity of early instruction. Longitudinal analyses revealed genetic continuity for both reading and spelling between kindergarten and Grade 1 across country. However, a new genetic factor comes into play accounting for independent variance in reading at Grade 1 in the U.S. and Scandinavia, suggesting a change in genetic influences on reading. Implications for response-to-instruction are discussed., Original publication: Stefan Samuelsson, Brian Byrne, Richard K. Olson, Jacqueline Hulslander, Sally Wadsworth, Robin Corley, Erik G. Willcutt and John C. DeFries, Response to early literacy instruction in the United States, Australia, and Scandinavia: A behavioral-genetic analysis, 2008, Learning and Individual Differences, (18), 3, 289-295.http://dx.doi.org/10.1016/j.lindif.2008.03.004. Copyright: Elsevier B.V., http://www.elsevier.com

Published
2008
Full Text
View/download PDF

171. The genetic and environmental etiologies of individual differences in early reading growth in Australia, the United States, and Scandinavia

Author

Christopher, Micaela E., primary, Hulslander, Jacqueline, additional, Byrne, Brian, additional, Samuelsson, Stefan, additional, Keenan, Janice M., additional, Pennington, Bruce, additional, DeFries, John C., additional, Wadsworth, Sally J., additional, Willcutt, Erik, additional, and Olson, Richard K., additional

Published
2013
Full Text
View/download PDF

172. The Nature and Nurture of High IQ

Author

Brant, Angela M., primary, Munakata, Yuko, additional, Boomsma, Dorret I., additional, DeFries, John C., additional, Haworth, Claire M. A., additional, Keller, Matthew C., additional, Martin, Nicholas G., additional, McGue, Matthew, additional, Petrill, Stephen A., additional, Plomin, Robert, additional, Wadsworth, Sally J., additional, Wright, Margaret J., additional, and Hewitt, John K., additional

Published
2013
Full Text
View/download PDF

175. Genetic and environmental influences on early literacy

Author

Byrne, Brian, Olson, Richard, Samuelsson, Stefan, Wadsworth, Sally, Corley, Robin, DeFries, John. C, Willcutt, Eric, Byrne, Brian, Olson, Richard, Samuelsson, Stefan, Wadsworth, Sally, Corley, Robin, DeFries, John. C, and Willcutt, Eric

Abstract

Prereading and early reading skills of preschool twin children in Australia, Scandinavia and the United States were explored in a genetically sensitive design (max. N = 627 preschool pairs and 422 kindergarten pairs). Analyses indicated a strong genetic influence on preschool phonological awareness, rapid naming and verbal memory. Print awareness, vocabulary and grammar/morphology were subject primarily to shared environment effects. There were significant genetic and shared environment correlations among the preschool traits. Kindergarten reading, phonological awareness and rapid naming were primarily affected by genes, and spelling was equally affected by genes and shared environment. Multivariate analyses revealed genetic and environmental overlap and independence among kindergarten variables. Longitudinal analyses showed genetic continuity as well as change in phonological awareness and rapid naming across the 2 years. Relations among the preschool variables of print awareness, phonological awareness and rapid naming and kindergarten reading were also explored in longitudinal analyses. Educational implications are discussed. © United Kingdom Literacy Association 2006.

Published
2006
Full Text
View/download PDF

177. Environmental and genetic influences on prereading skills in Australia, Scandinavia, and the United States

Author

Samuelsson, Stefan, Byrne, Brian, Quain, Peter, Wadsworth, Sally, Corley, Robin, DeFries, John. C, Willcutt, Eric, Olson, Richard. K, Samuelsson, Stefan, Byrne, Brian, Quain, Peter, Wadsworth, Sally, Corley, Robin, DeFries, John. C, Willcutt, Eric, and Olson, Richard. K

Abstract

Individual differences in measures of prereading skills and in questionnaire measures of 4-5-year-old twins' print environments in Australia, Scandinavia, and the United States were explored with a behavioral-genetic design. Modest phenotypic correlations were found between environmental measures and the twins' print knowledge, general verbal ability, and phoneme awareness. Lower print knowledge in Scandinavian twins was related to country differences in preschool print environment. Latent-trait behavioral-genetic analyses indicated very strong shared-environment influences on individual differences in Print Knowledge. Genetic influence was also significant. Several other prereading skills varied in their environmental and genetic influence, including a significant contrast between Phonological Awareness and Print Knowledge. Rapid Naming also revealed very strong genetic influence, as did Verbal Memory. Stronger shared-environment influences were found for Vocabulary and Grammar/Morphology. Genetic and environmental correlations among latent traits for General Verbal Ability, Phonological Awareness, and Print Knowledge were high, but there were also significant independent genetic and environmental contributions to each skill. Practical implications include the need for substantial and sustained instructional support for children hampered by genetic constraints on early literacy development. Copyright 2005 by the American Psychological Association.

Published
2005
Full Text
View/download PDF

184. Genetic and Environmental Influences on Vocabulary and Reading Development

Author

Olson, Richard K., primary, Keenan, Janice M., additional, Byrne, Brian, additional, Samuelsson, Stefan, additional, Coventry, William L., additional, Corley, Robin, additional, Wadsworth, Sally J., additional, Willcutt, Erik G., additional, DeFries, John C., additional, Pennington, Bruce F., additional, and Hulslander, Jacqueline, additional

Published
2011
Full Text
View/download PDF

187. Correction: Identification of Candidate Genes for Dyslexia Susceptibility on Chromosome 18

Author

Scerri, Thomas S., primary, Paracchini, Silvia, additional, Morris, Andrew, additional, MacPhie, I. Laurence, additional, Talcott, Joel, additional, Stein, John, additional, Smith, Shelley D., additional, Pennington, Bruce F., additional, Olson, Richard K., additional, DeFries, John C., additional, Monaco, Anthony P., additional, and Richardson, Alex J., additional

Published
2010
Full Text
View/download PDF

190. Preliminary results from a longitudinal preschool twin study of early reading development

Author

Byrne, Brian, Delaland, Cara, Fielding-Barnsley, Ruth, Quain, Peter, Samuelsson, Stefan, Hoien, Torleiv, Corley, Robin, DeFries, John. C, Wadsworth, Sally, Willcutt, Eric, Olson, Richard. K, Byrne, Brian, Delaland, Cara, Fielding-Barnsley, Ruth, Quain, Peter, Samuelsson, Stefan, Hoien, Torleiv, Corley, Robin, DeFries, John. C, Wadsworth, Sally, Willcutt, Eric, and Olson, Richard. K

Published
2002

Catalog

Books, media, physical & digital resources
See catalog results