The genetic epidemiology of multiple sclerosis

Multiple sclerosis (MS) is a debilitating immunological and neurodegenerative disorder. Epidemiological studies have provided overwhelming evidence of complex genetic susceptibility to MS. However, with the exception of the human leukocyte antigen (HLA) locus, genetic studies have failed to consistently identify significant linkage or association with genes that modulate MS disease expression. Numerous functional candidate gene studies, linkage genomic screens, and locational candidate gene studies have been performed in an attempt to identify additional loci. However, these methods have demonstrated insufficient power to consistently identify genes or epigenetic factors for MS. More current approaches integrate information from a variety of sources (e.g. consistent linkage data, gene expression profiling, and functional characterization studies) and utilize high throughput methods (e.g. genotyping high density markers, utilizing pooling schemes and performing new statistical analyses) in an attempt to overcome power issues. The following article presents a review of MS genetics research and a brief overview of methods that are currently being developed and utilized for fine localization of MS loci, such as the method employed in the Genetic Analysis of Multiple sclerosis in EuropeanS (GAMES) study that is presented elsewhere in this journal. It is the hope of researchers that these methods will lead to the identification of susceptibility genes for MS that aid in elucidating pathogenic mechanisms and potential therapeutic strategies for this debilitating disease.