Multiple Sclerosis in Twins and Their Relatives

The increasing search for the causes of multiple sclerosis has led in the past two decades to a close reexamination of the old idea that constitutional or genetic factors may play some role in the etiology of this disease. The evidence currently presented for or against a hereditary background for multiple sclerosis comes chiefly from three sources: (a) reports in the literature of more than one case in a family; (b) genetic studies involving the relatives of patients with the disease, and (c) observations of twin cases. During the past 60 years instances of more than one case in a family have been reported with increasing frequency.1The genetic studies were initiated, so to speak, by the pioneering work of Curtius2and Curtius and Speer.3Three or four other genetic studies followed. Findings in these studies do not differ greatly from one another and are summarized in