the coverage of the full set of common and rare variants have been recently reviewed using sequence data and suggest that the initial calculations of the coverage of common platforms were overoptimistic [59]. Larger coverage of the real variants rather than those reported in the HapMap will require additional SNP discovery [60]. It is also important to emphasize that the majority of SNPs in commercially available arrays do not affect protein structure and appear unlikely to affect gene expression so that this design choice limits the discovery power of GWAS to locating chromosomal regions rather than the genetic variants that are responsible for the trait. This initial discovery may be sufficient for prognostic modeling, but understanding the mechanism that leads to the trait of interest will require more intensive studies such as fine mapping or sequencing for the discovery of functional variants [60].
