Population description and its role in the interpretation of genetic association
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Despite calls for greater clarity and precision of population description, studies have documented persistent ambiguity in the use of race/ethnicity terms in genetic research. It is unclear why investigators tolerate such ambiguity, or what effect these practices have on the evaluation of reported associations. To explore the way that population description is used to replicate and/or extend previously reported genetic observations, we examined articles describing the association of the peroxisome proliferator-activated receptor-gamma-γ Pro12Ala polymorphism with type 2 diabetes mellitus and related phenotypes, published between 1997 and 2005. The 80 articles identified were subjected to a detailed content analysis to determine (1) how sampled populations were described, (2) whether and how the choice of sample was explained, and (3) how the allele frequency and genetic association findings identified were contextualized and interpreted. In common with previous reports, we observed a variety of sample descriptions and little explanation for the choice of population investigated. Samples of European origin were typically described with greater specificity than samples of other origin. However, findings from European samples were nearly always compared to samples described as “Caucasian” and sometimes generalized to all Caucasians or to all humans. These findings suggest that care with population description, while important, may not fully address analytical concerns regarding the interpretation of variable study outcomes or ethical concerns regarding the attribution of genetic observations to broad social groups. Instead, criteria which help investigators better distinguish justified and unjustified forms of population generalization may be required.
KeywordsJournal Impact Factor European Origin Asian Origin Pro12Ala Polymorphism Population Description
The authors thank Karen Edwards PhD, and members of the University of Washington Center for Genomics and Public Health, for providing access to the in-progress HuGE review of the PPARγ Pro12Ala association with type 2 diabetes and related phenotypes upon which our analysis is based. The authors also acknowledge Lizzeth Belskus-Amador, Aniel Solis, and Tessa Steel for research assistance. The article benefitted from the critical review of Melissa Austin, PhD, as well as several anonymous reviewers. This work was supported by the National Institutes of Health [P50 HG003374 to W.B.] and the Centers for Disease Control [U36 CCU300430-23 and U10 CCU025038 to K. Edwards].
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