unsuccessful identification of the many genes for AUD. Genetic linkage studies are conducted using large extended families across multiple generations derived from at least one affected family member. Assembling extended pedigrees required for linkage studies is labor intensive and more difficult compared to assembling population-based samples (case-control) required for association studies. In addition, linkage mapping has very poor genomic resolution where large chromosomal regions are identified that contain multiple possible candidate genes within the identified region. Candidate gene association studies require nomination of a biologically relevant candidate gene or pathway to test for association with AUD. Because a priori knowledge is required this limits the potential of finding novel and unexpected genetic associations. The GWAS approach (discussed below) is not limited to nominating a specific candidate gene or pathway because it is a discovery based approach that interrogates a complete panel of common SNPs distrusted across the entire genome without dependence on an a priori hypothesis.
