Is multiple sclerosis severity a genetically influenced trait?

Multiple sclerosis (MS), an inflammatory demyelinating disease of the central nervous system of unknown pathogenesis, is a complex disease with a multifactorial etiology determined by both genetic and environmental factors. The pathological entity MS has a wide phenotype, and also the severity of the disease is widely variable. Clinical heterogeneity of the disease might arise from different genotype-phenotype interactions. Results of recent studies and theories about the modifying role of different genes in the course and the severity of MS are here discussed.