and heterogeneous phenotypes will be influenced by a diverse array of genetic factors that span the spectrum from private mutation to common variant. Dickson and colleagues [4],[5] recently took a step further, by arguing that rare variants might explain not only some of the heritability that is currently missing, but also that they may be the cause of a proportion of detected associations between complex traits and common SNPs from GWAS. Based on computer simulations, they proposed that some constellations of variants within a narrow frequency and effect size range can account for “many” of the observed associations between complex traits and common SNPs from GWAS. This is a strong claim and one that they say has important implications for the “design of future studies to detect causal variants.” It is of great importance to the research community to establish whether “many” represents an important proportion of GWAS results to date, since indeed this can impact on decisions of experimental design and allocation of research funds.
