The two most common sampling techniques for studies of association are the case–control design and the family-based design. Owing to demographical, biological, and random forces, genetic variants differ in allele frequency in populations around the world, creating population structure or stratification reflected by ancestry. As a consequence, case–control studies are susceptible to spurious associations between genetic variants and disease status [6]. As more data are assimilated for combined analysis, the challenge of spurious associations due to population structure increases [7-9].
