With recent advances in the efficiency of array-based high-throughput SNP genotyping technology 14, hundreds of thousands of SNPs are now routinely genotyped on sample sizes necessary to detect the modest genetic effects we expect for complex diseases 2. GWA studies have been undertaken to study a wide variety of diseases and phenotypes, often involving big consortia to obtain the necessary sample sizes. The success of recently published GWAs has shown that this approach can be powerful in helping to identify disease related loci 15. One of the largest published examples highlighting the success of GWA studies was conducted by the Wellcome Trust Case Control Consortium (WTCCC) where 17,000 individuals were genotyped with the GeneChip 500K Mapping Array Set (Affymetrix chip) panel to study seven different diseases 16. Subsequent studies showed that most of the significant associations in the WTCCC, as well as those found in other GWA studies, could be replicated and are thus very likely to be real. A summary of recent GWA publications attempting to assay at least 100,000 SNPs is available online and lists the results from hundreds of publications with thousands of SNPs significantly associated to a wide variety of diseases and phenotypes (http://www.genome.gov/gwastudies/).
