exclusive focus on the influence of rare variants would be appropriate. Furthermore, as DNA sequencing and other genomic technology costs decrease, the frequency and functional impact of different forms of variation beyond SNPs will also be better understood. In this context merely finding that a set of rare variants appears to be collectively associated with a phenotype in no way suggests that all those variants are indeed functional or causally related to the phenotype. Thus, the problem of assigning causality to rare variants in a set may be more pronounced than it is in assigning causality to a single common variant.
