Abstract
Impairments in reading and in language have negative consequences on life outcomes, but it is not known to what extent genetic effects influence this association. We constructed polygenic scores for difficulties with language and learning to read from genome-wide data in ~6,600 children, adolescents and young adults, and tested their association with health, socioeconomic outcomes and brain structure measures collected in adults (maximal N = 111,749). Polygenic risk of reading difficulties was associated with reduced income, educational attainment, self-rated health and verbal-numerical reasoning (p < 0.00055). Polygenic risk of language difficulties predicted income (p = 0.0005). The small effect sizes ranged 0.01–0.03 of a standard deviation, but these will increase as genetic studies for reading ability get larger. Polygenic scores for childhood cognitive ability and educational attainment were correlated with polygenic scores of reading and language (up to 0.09 and 0.05, respectively). But when they were included in the prediction models, the observed associations between polygenic reading and adult outcomes mostly remained. This suggests that the pathway from reading ability to social outcomes is not only via associated polygenic loads for general cognitive function and educational attainment. The presence of non-overlapping genetic effect is indicated by the genetic correlations of around 0.40 (childhood intelligence) and 0.70 (educational attainment) with reading ability. Mendelian randomization approaches will be important to dissociate any causal and moderating effects of reading and related traits on social outcomes.
Highlights
The major finding was that, expressed in positive terms, polygenic scores acting to increase reading ability were significantly associated with higher educational attainment, higher incomes and greater self-rated health as well as with higher verbal-numerical reasoning
Low to moderate genetic correlations between reading traits and childhood intelligence were found, but accounting for polygenic childhood intelligence effects did not significantly alter the polygenic reading associations with adult outcomes. These data might reflect a causal role of the pathway from reading to long-term social outcomes, consistent with a report of reading and language skills mediating the genetic effects on these social outcomes (Ritchie and Bates 2013; Ritchie et al 2013)
The polygenic reading ability associations were reduced when polygenic educational attainment was controlled for in the models. This suggests that shared genetic influences on reading ability and adult outcomes are, in part, mediated by genetic effects on educational attainment
Summary
Participants were drawn from the UK Biobank (http:// www.ukbiobank.ac.uk), an open resource enabling the study of factors influencing disease in mid- to late (40–69 years) adulthood (Sudlow et al 2015). Polygenic scores for childhood (6–18 years) general intelligence (Benyamin et al 2014) and adult educational attainment (college degree) (Rietveld et al 2013) were further created in UK Biobank based on the largest publicly available GWA studies estimated in respective sample sizes of 17,989 and 101,069. They were used to test whether reading and language polygenic scores effects were independent from the polygenic influences on general cognitive ability, and, as expected, whether they correlated with genetic influences on educational attainment. This latter method only relies on GWA summary statistics and is not biased by sample overlap
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