Based on these observations, it is reasonable to assume that, once GWA studies of a disease or trait have begun to yield associated loci, then larger sample sizes will yield additional associated loci, and that the number of loci will scale at least linearly with sample size. Of course, at some point increasing sample size will yield diminishing returns. This point might be recognized by a fall-off of associated loci from a linear pattern (this presumably would happen because new variants are being largely found in already-discovered loci). Alternatively, if new loci consistently contain genes in already recognized pathways, then the gain in biological insight may be limited even if large numbers of new loci remain to be discovered. Moreover, the effect sizes (variance explained) of new discovered loci will tend to be on average smaller than those of early discovered loci.
