We used a genome-wide significance level of p < 1.21 × 10−8 and a suggestive level of significance of p < 1.21 × 10−5 as proposed for the Illumina 317K panel of markers (adjusted for SNP non-independence) (Duggal et al., 2008). While this is a liberal criterion because we used a larger chip, no SNPs reached genome-wide significance. Using the genome-wide significance alpha level, power calculations for our maximum sample were 36% to detect an effect size of 1% which increased to 80% for an effect size of 1.5%; the more liberal suggestive significance level gave a power of 83% to detect an effect size of 1%. We also present supplementary results of our top 100 SNPs because evidence is accumulating that for complex traits (e.g., height) effect sizes are too small to pass the stringent significance tests of genome-wide association (Yang et al., 2010).
