Genetic association studies are increasingly used in the search for susceptibility variants for human traits. While many of the statistical tools available for such studies are well established, the field is advancing rapidly, as biological and technological developments allow investigators to generate vast amounts of detailed genetic data. This chapter gives an overview of the statistical evaluation of genetic data in both unrelated individuals and families. A brief introduction to fundamental population genetics concepts is followed by detailed examinations of measures of linkage disequilibrium and single-marker and haplotype association tests. Emphasis is given to the historical development of family-based tests to provide the context for more recent advancements. The chapter concludes with a discussion of design strategies for genetic association studies with dense genotyping of hundreds or thousands of markers, such as those planned for follow up of a linkage-candidate region or genome-wide association studies.
