King Jordan, Ph.D.
Georgia Institute of Technology
School of Biological Sciences

Abstract
The ChocoGen research project was initiated to facilitate genomic studies of the predominantly Afro-Colombian population of Chocó, a state located on Colombia's Pacific coast.  The project aims to (1) characterize the genetic ancestry of the population of Chocó, and (2) explore the relationship between ancestry and genetic determinants of health in the region.  We compared genome-wide patterns of genetic ancestry for Chocó to six other admixed American populations, with an emphasis on a Mestizo population from the neighboring state of Antioquia.  Chocó shows mostly African genetic ancestry (76%) with a nearly even split between European (13%) and Native American (11%) fractions, whereas Antioquia has primarily European ancestry (75%), followed by Native American (18%) and African (7%).  Sample donors from Chocó self-identify as having more African ancestry than can be genetically inferred, as opposed to what we previously found for Antioquia, where individuals tend to overestimate levels of European ancestry.   Despite the clear differences between Chocó and Antioquia at the level of continental ancestry, the two populations show overall patterns of subcontinental ancestry that are highly similar.  We investigated the role that genetic ancestry plays in the epidemiology of type 2 diabetes (T2D) for these two Colombian populations.  Chocó has significantly higher predicted genetic risk for T2D compared to Antioquia, and the elevated predicted risk for T2D in Chocó is correlated with higher African ancestry. Despite its elevated predicted genetic risk, the population of Chocó has a three-times lower observed T2D prevalence than Antioquia, indicating that environmental factors better explain differences in T2D outcomes for Colombia.  However, Chocó has substantially lower socioeconomic status (SES) than Antioquia, which is unexpected given that low SES is widely considered to be an environmental risk factor for T2D.  Our exploration of the dietary and lifestyle factors that characterize low SES in Chocó illustrates how poverty can divergently manifest as a T2D protective factor in Colombia.

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