CHD8 and cancer: In contrast, the apparently significant effects that were observed in the control gene sets (cancer and CD), as well as the gene set downregulated in the presence of excess MIR137 and the gene set upregulated in the absence of CHD8, were not higher than a floor effect observed with random sets of genic SNPs and non-genic SNPs and could be attributable to an omnigenic or highly polygenic background [12].