MRC Integrative Epidemiology Unit (IEU) Seminar Series

Title: Lessons from large-scale GWAS of self-reported diet & physical activity

Abstract: Lifestyle choices such as dietary intake and physical activity have a non-negligible heritable component. This genetic component is likely to be a mixed bag of genetic influences on taste preferences, health, reward-sensitivity, metabolic efficiency, and socioeconomic status. To study the genetic underpinnings of lifestyle choices, I present findings from two genome-wide association studies (GWAS) which are undertaken under the auspices of the Social Science Genetic Association Consortium (SSGAC). The first study concerns the largest genome-wide association study (GWAS) on diet composition to date. The second study concerns a large-scale GWAS of overall physical activity in the UK Biobank. Our measure of diet composition comprises four phenotypes, which broadly represent energy intake from fat, protein, carbohydrate, and sugar. These phenotypes were created on the basis of self-report data in 18 different genotyped samples. With a total sample size of N ~ 265k for fat, protein and carbohydrate, and N ~ 234k for sugar, we discover 21 unique independent loci, revealing surprising genetic associations with health outcomes and indicators of socioeconomic status. In our study on physical activity, we develop a composite measure of self-reported physical activity in the UK Biobank. Published GWAS of physical activity have either focused on a small UKB sample with wristband accelerometer data, or have exclusively analyzed single-question variables. Our measure maximizes the statistical power for genetic discoveries on physical activity by making optimal use of available data in the UKB, yielding a sample size of N ~ 438k. While the SNP-based heritability of our measure is substantially lower than that of the accelerometer-based phenotype, the pattern of genetic correlations with activity-related health outcomes is indistinguishable from the accelerometer phenotype’s pattern. Our studies show the value of leveraging phenotype information in lifestyle choices.

 

Biography: Fleur Meddens is a postdoctoral researcher at the department of Health Economics of the Erasmus School of Economics. She currently studies how socioeconomic inequalities are affected by the interaction between genetic risks and (quasi-experimental) environments. She has a particular interest in lifestyle and obesity, mental health and wellbeing, and gender inequalities. As a collaborator of the Social Science Genetic Association Consortium (SSGAC), she was the lead author of a large-scale genome-wide association study (GWAS) on dietary intake, and a co-author of GWAS on education, wellbeing, and risk preferences. She is currently undertaking a large-scale GWAS of physical activity.

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