In addition, we were not able to perform thorough admixture tests in all datasets due to variable genotyping. Population stratification unaccounted for by our stratified analyses of self identified ancestry - European, Asian, and African American - could be a confounder in our results. Although we are leveraging the admixture to separate the effects of different genetic variants, there may be differential admixture in the cases and controls among African Americans. The impact of varied genetic architecture within given, broadly defined populations as well as within and across populations represented by individual sites (e.g., Japanese, Chinese, and Korean) needs to be elucidated in future larger scale studies with sufficient representation of individuals from different population backgrounds and more comprehensive genotyping.
