We genotyped all study participants for 186 ancestry informative markers (AIMs) that were included on the Addictions Array (Hodgkinson et al., 2008). The 186 AIMs represent a subset of a previously defined set of 204 AIMS (Enoch, Shen, Xu, Hodkinson, & Goldman, 2006). We ran STRUCTURE (Pritchard, Stpehens, & Donnelly, 2000) to identify subpopulations of individuals using these AIMs. All participants’ self-reported Caucasian ancestry was confirmed.
