A new dawn for genetic association studies in multiple sclerosis.

Before the genomics technology revolution allowed us to do genome-wide science, genetics research relied on our limited knowledge about a subject to generate hypothesis and candidate genes to study. Despite the level of naiveté, several associations with susceptibility to a complex disease such as multiple sclerosis (MS) were discovered. Of these, HLA-DRB1 and IL7R (1) stand out as being confirmed and refined early by the genome-wide association studies (GWAS) that followed.(2) Despite the expense and gargantuan efforts, these GWAS have successfully led to the discovery of more than 100 additional genes, albeit with smaller effect sizes, that contribute to MS susceptibility.(3) This list keeps growing, but it comes with no surprise that most of these genes identified the immune system as one large candidate for MS susceptibility.