Chunk #59 — 6.0 How Do Electrophysiological Endophenotypes Compare with Other Quantitative Traits? — 6.3 Summary: Endophenotype genetic effect sizes and architecture resemble that seen for other complex traits
In summary, endophenotypes are like other complex traits; they are unlikely to be associated with variants that have large effect sizes, which is consistent with the findings from our special issue. Table 2 indicates that the maximum effect size we obtained for each endophenotype was small, but roughly in the range of what one might expect a large effect size to be for a biomedical or psychological trait. Yet we were underpowered to detect any as significant but one. Nor was it the case that the genetic signal was “hiding” in rare variants; our rare variant analyses yielded no more compelling result. In addition, GREML SNP heritability estimates indicate that the aggregate influence of all variants on most endophenotypes is substantial, and little different from what we see in other traits like height. This combination of findings highlights the fact that endophenotypes are massively polygenic, with many thousands of variants each contributing very small effects. Although our results could be unique to our set of endophenotypes and sample, the data available for other heritable quantitative traits, such as those listed
