Null findings are now the norm in individual GWASs, and they are often taken as an indication of polygenic inheritance; common phenotypes are due to a large number of genes, each with very small effect, such that individual GWASs are underpowered to detect them. Thus, individual GWASs may not be well suited for discovery. Larger samples obtained through meta-analysis are likely required, as demonstrated recently for volume of the hippocampus (Stein et al., 2012). An implication of this is that one promise of endophenotypes — that they might help identify genes for psychiatric disorders — cannot yet be meaningfully assessed, and it may never be meaningfully assessed. In the present investigation we obtained several findings that were significant even with Bonferroni correction of (endophenotype-wide) Type I error rate. By contrast, a GWAS of behavioral phenotypes in a sample that is essentially a superset of the sample used here and that is approximately twice as large, did not obtain any genome-wide significant findings (McGue et al., 2013). Does this imply that the EEG endophenotypes we examined are better situated to detect
