title: Generalist genes and learning disabilities: a multivariate genetic analysis of low performance in reading, mathematics, language and general cognitive ability in a sample of 8000 12-year-old twins.
abstract: BACKGROUND
  Our previous investigation found that the same genes influence poor reading and mathematics performance in 10-year-olds. Here we assess whether this finding extends to language and general cognitive disabilities, as well as replicating the earlier finding for reading and mathematics in an older and larger sample.
  
  
  METHODS
  Using a representative sample of 4000 pairs of 12-year-old twins from the UK Twins Early Development Study, we investigated the genetic and environmental overlap between internet-based batteries of language and general cognitive ability tests in addition to tests of reading and mathematics for the bottom 15% of the distribution using DeFries-Fulker extremes analysis. We compared these results to those for the entire distribution.
  
  
  RESULTS
  All four traits were highly correlated at the low extreme (average group phenotypic correlation = .58). and in the entire distribution (average phenotypic correlation = .59). Genetic correlations for the low extreme were consistently high (average = .67), and non-shared environmental correlations were modest (average = .23). These results are similar to those seen across the entire distribution (.68 and .23, respectively).
  
  
  CONCLUSIONS
  The 'Generalist Genes Hypothesis' holds for language and general cognitive disabilities, as well as reading and mathematics disabilities. Genetic correlations were high, indicating a strong degree of overlap in genetic influences on these diverse traits. In contrast, non-shared environmental influences were largely specific to each trait, causing phenotypic differentiation of traits.
authors: Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, UK.
authors: Claire M A
authors: CM
authors: Haworth
authors: Yulia
authors: Y
authors: Kovas
authors: Nicole
authors: N
authors: Harlaar
authors: Marianna E
authors: ME
authors: Hayiou-Thomas
authors: Stephen A
authors: SA
authors: Petrill
authors: Philip S
authors: PS
authors: Dale
authors: Robert
authors: R
authors: Plomin
mesh_terms: D002648:Child; D003072:Cognition Disorders / Q000453:epidemiology / Q000235:genetics; D004739:England / Q000453:epidemiology; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D040582:Inheritance Patterns; D007806:Language Disorders / Q000453:epidemiology / Q000235:genetics; D007859:Learning Disabilities / Q000453:epidemiology* / Q000235:genetics*; D008297:Male; D008433:Mathematics; D008957:Models, Genetic; D015999:Multivariate Analysis; D012307:Risk Factors; D014852:Wales / Q000453:epidemiology