Genotyping and cost improvements now permit routine assessment of a million or more genetic variants distributed across the genome (Beaudet and Belmont, 2008). GWAS can extract information from most common genetic variants in the genome either through direct assessment of single nucleotide polymorphisms (SNPs) or indirectly via linkage disequilibrium between genotyped SNPs and unmeasured but correlated genetic variants. Despite the advantages of genome-wide genotyping (Hindorff et al., 2009), stringent adjustment for multiple comparisons is required which necessitates the use of large sample collections.
