but it remains the most commonly used approach to date (50). Another cause of the false-positive associations to which GWA studies are prone is population stratification. Allele frequencies vary between population subgroups, such as those defined by ethnicity or geographic origin, and these subgroups in turn differ in their risk for disease. GWA studies may then falsely identify the subgroup-associated genes as related to disease (50). Genotyping error is another important cause of spurious associations that must be carefully sought and corrected.
