Sponsored by:
Senior Genomic Data Scientist and GWAS Data Coordinator
National Longitudinal Study of Adolescent to Adult Health
Carolina Population Center
University of North Carolina at Chapel Hill
The unique composition of microorganismal species that colonizes the gut of each person develops intimate links to health and disease over time and varies by social status and contexts. Variation in the types and abundance of microbes present in the gastrointestinal system promotes an active immune system and healthy metabolism, while dysregulation has been associated with numerous negative health outcomes including inflammatory autoimmune disorders and cardiometabolic diseases. Various factors are known to associate with decreases in microbial richness of the gut microflora including sociodemographic factors, socioeconomic status, and health behaviors. It is less well known how geographical proximity and genetic relatedness modify the levels of microbial diversity of the gut microbiome. We seek to understand the diversity of the microbiomes of a representative subset of participants in the National Longitudinal Study of Adolescent to Adult Health (Add Health) during the Wave V interview (2016-18). The Add Health Microbiome Pilot Study included 746 participants who represent a wide range of demographic, socioeconomic, and health behaviors. Pilot participants reside in all 50 states of the United States and nearly all share proximity to at least one other individual at the county and/or tract level. Also, this particular subsample includes 226 individuals who share familial relatedness with at least one other participant in the subsample at the level of monozygotic twins, dizygotic twins, full sibling, or half siblings. Using this pilot subset of participants from the Add Health study, we explore how the microbial diversity of the gut at the individual level (alpha diversity) and at the population level (beta diversity) is associated with sociodemographic characteristics, socioeconomic factors, and health behaviors. We then examine how diversity levels are correlated according to the geographic proximity and to a lesser extent, genetic relatedness of subsample pairs. We demonstrate that in a fully controlled model, geographic location is a better predictor of microbiome similarity than any other factor measured. Finally, we show that familial relatedness is only a modest predictor of microbial variation in second- and third-degree relatives. This analysis of the diversity of the gut microbiome of a large number of individuals aims to shed light on the relative importance of demographic, socioeconomic, behavioral, geographic, and genetic factors in determining the richness and evenness of bacterial communities living inside them.