Genes associated with multiple sclerosis: 15 and counting.

Evaluation of: The International Multiple Sclerosis Genetics Consortium (IMSGC). IL12A, MPHOSPH9/CDK2AP1 and RGS1 are novel multiple sclerosis susceptibility loci. Genes Immun. 11(5), 397-405 (2010). Multiple sclerosis (MS) develops in genetically susceptible populations as a result of environmental exposures, and discovering these genetic and/or environmental factors will provide fundamental new insights into the pathogenesis, diagnosis and treatment of this disabling disease. With the introduction of genome-wide association studies, the number of genes found to be associated with MS has increased rapidly. In all of these genes, in a study by the International Multiple Sclerosis Genetics Consortium, the classic MS risk locus, HLA-DRB1, stood out with remarkably strong statistical significance, but they also identified 12 other loci and/or genes associated with MS. However, all of these alleles have a very modest odds ratio and they explain approximately 3% of the variance in MS risk. Recently, the International Multiple Sclerosis Genetics Consortium provided evidence for three new loci that show significant association at a genome-wide level: RGS1, IL12A and MPHOSPH9/CDK2AP1. In this article, we will review the three newly discovered susceptibility loci and the implications of genome-wide association studies in MS on clinical practice.