“…Over the past 50 years, epidemiological and clinical studies have established that genetic factors play an important role in the predisposition to MS (6,24,100,159,182). Evidence for genetic factors in MS comes from family studies that show an increased prevalence of MS in sibs, parents, and children of affected individuals and from twin studies that show a higher concordance in monozygotic than in dizygotic twins (6,24,45,48,114,140,159,205,269). Further evidence comes from the observation that MS is associated with specific HLA antigens in some populations (6,8,24,56,83,91,99,143,169,231,233,265); other genes that influence susceptibility to or the course of MS have also been postulated (16,24,171,215,241,260) although some of these data are preliminary and, in some instances, conflicting (89,138,139,200).…”