1 Refining the association of MHC with multiple sclerosis in African Americans

g.oxfordjournals.org/ D ow nloaded from 2 Multiple sclerosis (MS) is a common demyelinating disease of the central nervous system mediated by autoimmune and neurodegenerative pathogenic mechanisms. Multiple genes account for its moderate heritability, but the only genetic region shown to have a large replicable effect on MS susceptibility is the major histocompatibility complex (MHC). Strong linkage disequilibrium (LD) across the MHC has made it difficult to fully characterize individual genetic contributions of this region to MS risk in previous studies. African Americans are at a lower risk for MS when compared to northern Europeans and Americans of European descent, but greater haplotypic diversity and distinct patterns of LD suggest that this population may be particularly informative fo