A total of 1432 European and 1388 African Americans with targeted sequencing of CHRNA5 and available smoking behaviors were examined. Data were analyzed using the Statistical Analysis System (SAS 9.3, Cary, NC, USA). Logistic regression was used to model case-control status. European and African Americans were analyzed separately. Ancestry groups were verified using EIGENSTRAT23 and previously collected genome-wide arrays. Ten ancestry-specific principal components (PCs) were developed. Examination of eigenvalues led us to include the first PC in our statistical analyses of both ancestry groups. All models included the standard covariates of sex, age, and first ancestry-specific PC.
