What has become evident in GWAS of other diseases is that large-scale, multi-center collaborations are needed to obtain a sample sufficiently large enough to provide adequate power for a GWAS. A recent genome-wide association analysis of bipolar disorder, which combined three datasets [109–111] totaling over 4300 cases and 6200 controls [109], detected two markers with genome wide significant association. Combining the datasets was instrumental in providing enough power to reach a genome-wide level of statistical significance, since none of these associations were detected in the individual samples.
