Multiple sclerosis (MS) is an autoimmune, neuroinflammatory demyelinating disease, with a propensity for onset in middle-aged women, although it can occur in men and is rarely diagnosed in those above 65 years. Other risk modifiers include distance from the equator, as prevalence increases with greater latitudes. This is thought to be associated with low vitamin D, which also results in a predisposition to develop multiple sclerosis. Additionally twin studies show that there is some extent of a genetic component of MS as concordant rates of acquiring MS in monozygotic twins were 30% as opposed to 5% in dizygotic twins.