Genome-wide association studies have successfully identified a growing number of
common variants that robustly associate with a wide range of complex diseases and
phenotypes. In the majority of cases though, the variants are predicted to have small to
modest effect sizes, and, due to the technologies used, many of the signals discovered
so far may not be the causal loci. As rare variation studies begin to explore the lower
ranges of the allele frequency spectrum, using whole genome or whole exome
sequencing to capture a larger proportion of variants, we expect to find variants with a
more direct causal role in the phenotype(s) of interest. Interpreting possible functional
mechanisms linking variants with phenotypes will become increasingly important
