be detected through conventional association analysis. The power of detection for a rare variant is proportional to the product of its frequency (which is small) and the square of its effect size. Hence rare variants will be detected only if their effect sizes are large enough given their low frequency. Our results imply that there are many chromosomal regions that contain causal variants and so most must explain a small proportion of total variance. Such small contributions can be due to loci with very low MAF and large effect sizes but our ability to detect them by association is limited by the amount of variance explained.
