it more difficult to isolate the signal associated with disease outcomes. Nevertheless, in comparison with GWA studies, which use population-based samples and are powered to detect common variants with modest effects, traditional family linkage studies may have greater power to detect rare variants associated with drug addiction phenotypes. To some extent the same argument applies to the use of founder populations and genetic isolates in which some variants that are rare on a world-wide basis can be expected to be far more common in these samples.
