Despite this progress, the identified susceptibility loci explain only a small fraction (approximately, < 2%) of the AD heritability [1]. This phenomenon is known as “missing heritability” [17]. Therefore, many genetic variants that influence risk for AD remain undiscovered [7]. In fact, many variants of small effect are unlikely to be identified individually given the relatively small samples that are available and the stringent significance threshold that is required. In this study, we explored the genetic architecture of AD in African-Americans via analysis of a genomewide set of common variants, adopting the framework proposed by Yang et al. [31,33].
