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Recent psychological and neuropsychological research suggests that executive functions--the cognitive control processes that regulate thought and action--are multifaceted and that different types of executive functions are correlated but separable. The present multivariate twin study of 3 executive functions (inhibiting dominant responses, updating working(More)
DYX2 on 6p22 is the most replicated reading disability (RD) locus. By saturating a previously identified peak of association with single nucleotide polymorphism markers, we identified a large polymorphic deletion that encodes tandem repeats of putative brain-related transcription factor binding sites in intron 2 of DCDC2. Alleles of this compound repeat are(More)
Although common sense suggests that environmental influences increasingly account for individual differences in behavior as experiences accumulate during the course of life, this hypothesis has not previously been tested, in part because of the large sample sizes needed for an adequately powered analysis. Here we show for general cognitive ability that, to(More)
Accumulating evidence suggests that executive functions (EFs) are related to intelligence, despite neuropsychological results initially considered evidence of no such relation. However, findings that EFs are not unitary raise the issue of how intelligence relates to different EFs. This study examined the relations of fluid and crystallized intelligence and(More)
Several quantitative trait loci (QTLs) that influence developmental dyslexia (reading disability [RD]) have been mapped to chromosome regions by linkage analysis. The most consistently replicated area of linkage is on chromosome 6p23-21.3. We used association analysis in 223 siblings from the United Kingdom to identify an underlying QTL on 6p22.2. Our(More)
A candidate gene, EKN1, was recently described in a cohort from Finland for the dyslexia locus on chromosome 15q, DYX1. This report described a (2;15) (q11;21) translocation disrupting EKN1 that cosegregated with dyslexia in a two-generation family. It also characterized a sequence polymorphism in the 5' untranslated region and a missense mutation that(More)
Psychological traits are commonly inferred from covariation in sets of behavioral measures that otherwise appear to have little in common. Emotionality in mice is such a trait, defined here by covariation in activity and defecation in a novel environment and emergence into the open arms of an elevated plus maze. Behavioral and quantitative trait analyses(More)
Reading disability (RD), or dyslexia, is a complex cognitive disorder manifested by difficulties in learning to read, in otherwise normal individuals. Individuals with RD manifest deficits in several reading and language skills. Previous research has suggested the existence of a quantitative-trait locus (QTL) for RD on the short arm of chromosome 6. In the(More)
Developmental dyslexia is defined as a specific and significant impairment in reading ability that cannot be explained by deficits in intelligence, learning opportunity, motivation or sensory acuity. It is one of the most frequently diagnosed disorders in childhood, representing a major educational and social problem. It is well established that dyslexia is(More)