Ellen Verhoef [Pause] Welcome to the video abstract of “The Developmental Origins of Genetic Factors Influencing Language and Literacy Associations with Early-Childhood Vocabulary,” that was published last year in the Journal of Child Psychology and Psychiatry. I am Ellen Verhoef and I will guide you through our findings, together with Beate St Pourcain. Observational studies show that early language skills are predictive of later cognitive development, such as reading skills, but also non-performance intelligence and educational outcomes at the end of primary school. These associations may arise due to shared aetiologies, as proposed by the Simple View of Reading theory. The Generalist Genes Hypothesis proposes that these shared aetiologies are also reflected in the genetic architectures of cognition-related traits, with shared genetic factors among cognitive abilities. Inheritability of cognition-related traits, including language and literacy-related skills, tends to increase during development. One way to interpret this increase is in terms of innovation and amplification. Previous studies on cognitive abilities, as well as language and reading skills, found that predominantly innovation processes account for the increase in heritability observed in the transition from early to middle childhood. These studies were, however, exclusively based on latent factor twin modelling. Beate St Pourcain Here, we investigated whether genetic factors contributing to language, literacy and cognition in mid-childhood and early adolescent already relate to genetic factors underlying vocabulary skills in early childhood, or whether these genetic factors emerge during the course of development. We studied genetic architectures using genetic marker information in a sample of unrelated children, is captured by genotyping chips. Specifically, we investigated genetic factors related to expressive, and for the first time, also receptive, vocabulary at three years of age, and examined multivariate genetic relationships with respect to a wide spectrum of later life skills. Ellen Verhoef We studied children and adolescents with genome-wide genotyping and behavioural data from the Avon Longitudinal Study of Parents and Children, a UK-based longitudinal pregnancy ascertained birth cohort. About 6,000 children had data on early vocabulary at 38 months assessed using parental report, based on the MacArthur-Bates Communicative Development Inventories. In addition to early language phenotypes, we studied 14 traits that were directly assessed in children and young adolescents between the age of seven and 13 years, using standardised and ALSPAC specific psychological instruments. Beate St Pourcain SNP heritability for early for early vocabulary was modest, with estimates of 18% and 12% for expressive and receptive vocabulary goals respectively. In comparison, SNP heritabilities for later phenotypes were moderate, reaching up to 54%. These findings are consistent with an increase in heritability across development, as previously reported in the literature. At the phenotypic level, both expressive and receptive vocabulary scores are related with all later verbal and cognitive child and adolescent traits investigated. At a genetic level, however, evidence for shared genetic factors with later life abilities were only observed for receptive vocabulary. Expressive vocabulary was only related to later life verbal IQ. Ellen Verhoef Next, we modelled multivariate genetic variances between expressive and receptive vocabulary at 38 months and, in turn, each of the 14 mid-childhood/early adolescent traits, using genetic relationship matrix structure equation models. This method models genetic links between traits based on data from unrelated individuals, using genetic relationship matrixes derived from genome-wide SNP information. We favoured Cholesky decompositions to each trivariate model, containing three genetic and residual factors, explaining all phenotypic information. This is also known as a saturated model. Beate St Pourcain Here, I will talk you through our findings based on a structural equation model for early vocabulary and verbal IQ. On the left side of the slide the path diagram will appear, with arrows indicating which genetic factor is related to which trait, known as factor loading. Square boxes represent the observed phenotypes and circles represent genetic and residual factors. On the right side of the slide a diagram detailing the estimated genetic variants explained by each genetic factor will appear. The orange boxes in this plot represent the total SNP heritability. The first genetic factor, A1, explains 17% of the variation in expressive vocabulary at 38 months, but also 9% of the variation in receptive vocabulary and verbal IQ. The second genetic factor, A2, which is independent of A1, explains the remaining genetic variants in receptive vocabulary, which is only 4%. In contrast, the variance that this factor explains in verbal intelligence increases dramatically, reaching 45%. As the bar plot already indicated, there was little evidence for a genetic factor that was only related to verbal IQ. This pattern suggests that early genetic influences are stable and amplified across development. Ellen Verhoef We followed up work from this paper in a new manuscript that was recently published in PLOS Genetics, where we fully investigated genetic links between mid-childhood abilities and early vocabulary assessed between 15 and 38 months. This analysis showed that at least two different genetic factors contribute to phenotype variation in mid-childhood and are amplified during development. The earliest genetic factor that was related to mid-childhood skills was already detectible at the age of 24 months, in addition to genetic influences that are unique to receptive vocabulary at 38 months, consistent with our earlier findings. For performance intelligence, on the other hand, we only obsorved – observed robust evidence for shared genetic variance with receptive vocabulary. This suggests that the genetic foundations of mid-childhood reading and cognitive abilities are diverse and may differ for verbal and non-verbal traits. Plus, together, our findings suggest that the developmental origins of genetic factors contributing to mid-childhood and early adolescent language, literacy and cognition, lie in early childhood, consistent with genetic stability. We found evidence for an amplification of early genetic influences. These genetic influences are predominantly, but not exclusively, related to receptive vocabulary. Also, genetic factors that are related to early expressive vocabulary, contribute to variation in later reading and verbal cognitive skills. The observed amplification patterns might be due to genotype environment correlations, different effects of the same genes over time and/or reduced measurement error. Furthermore, our findings suggest that the developmental origins of genetic factors influencing later life skills are diverse. They only partially support the Generalist Genes Hypothesis. Similar to other studies of unrelated individuals, a general limitation of this work is that our results might be confounded by population stratification, assortative mating and/or indirect genetic effects. In addition, these analyses were all based around transformed scores to allow for comparison of different psychological instruments and data distribution. With this, we would like to conclude and thank our co-authors, participants and Researchers related to ALSPAC, as well as the Max Planck Society, for funding us, and JCPP for providing us with the opportunity to communicate our research in this short talk. Thank you very much.