Analyzing Shared Complex Trait Architecture Among Phenotypes in Four Ancestral Human Populations

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Abstract:
Genome-wide association (GWA) studies identify statistical associations between individual variants and a phenotype of interest. By independently testing the correlation between the allelic state at each variant and a particular phenotype, variants that significantly contribute to trait development can be identified. Some traits are controlled by only a few variants – e.g. age-related macular degeneration – while others, like height, have been shown to be controlled by tens of thousands of variants spread across the genome. To date, these studies have disproportionately been conducted with samples from European populations. Yet, the extent to which the genetic architecture of complex phenotypes may differ between ancestries remains unknown. Further research into the shared genetic architecture in different ancestries is needed to understand how these variants contribute to complex trait architecture. In this study, we performed GWA studies for 25 different traits in four different ancestral cohorts (African, European, South Asian, and East Asian). In addition, we used a novel statistical framework, gene-ε, to aggregate variant-level association signals across entire regions of the genome (genes and transcriptional elements) and produce regional association statistics for each cohort-phenotype combination. For each cohort, we then used these regional association statistics, or “gene scores,” as input into the WINGS algorithm to identify prioritized clusters of phenotypes that have shared deterministic genetic elements. We show that two prioritized phenotype clusters are identified all four ancestries while three are identified in at least two ancestral cohorts. These results indicate that many groups of phenotypes share common genetic determinants regardless of ancestral cohort and emphasize the need for exhaustive testing of genetic trait architecture across both ancestries and complex phenotypes.

Citation

Zhang, Selena, Smith, Samuel, and Ramachandran, Sohini, "Analyzing Shared Complex Trait Architecture Among Phenotypes in Four Ancestral Human Populations" (2020). Summer Research Symposium. Brown Digital Repository. Brown University Library. https://repository.library.brown.edu/studio/item/bdr:1138469/

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    Each year, Brown University showcases the research of its undergraduates at the Summer Research Symposium. More than half of the student-researchers are UTRA recipients, while others receive funding from a variety of Brown-administered and national programs and fellowships and go …

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