is similar to the statistics usually found in candidate gene association studies. For a statistical power of 0.80 (β = 0.20) using the allelic test, the minimum sample size for a case-control study is 1,062, with equal numbers of cases and controls. Of the reported 201 candidate gene association studies, only 88 have had a sample size of 1,000 or more. Considering the detected power of 0.54 for a sample size of 500 under the dominant genetic model, we also included genes implicated in studies with 500–1,000 subjects if the genes were located in a nominated linkage peak34 or overlapped with GWAS signals. In total, 34 genetic loci with 43 genes met the criteria (Table 2 and Figure 1), which were assigned to the following four groups. For details on those studies that failed to pass the thresholds but show positive associations, please see Supplementary Table 1.
