Familial Incidence of Disseminated Sclerosis

IN Northern Ireland we have recently completed a survey of disseminated sclerosis; 700 cases have been traced and examined and in 44 families we have found more than one member affected, giving a familial incidence of 6.58 per cent.; this figure corresponds closely with the incidence in recent surveys from the Middlesex Hospital 6.5 per cent. (Pratt, et al., 1951), and from the Bristol area 6 per cent. It is only in the past decade that the familial aspect of the disease has been generally recognized in the English literature, although the subject was much discussed on the Continent. As recently as 1930 Russell Brain, in a review of the literature of disseminated sclerosis, stated: "In striking contrast to diseases attributable to an inherited germinal defect, multiple cases of disseminated sclerosis in one family are extremely rare compared with sporadic cases, and its occurrence in more than two members of a family and in two successive generations is almost unknown. These facts suggest that inherited predisposition plays no part in the aetiology of the disease, and that the occasional occurrence of multiple cases in one family is due either to chance, exposure to a common environment or mutual infection." Curtius (1933) made an extensive study of the 2,778 near and distant relatives of 56 cases of disseminated sclerosis in Bonn and a less extensive study of 346 relatives of a further 50 cases in Heidelberg. In the Bonn series he found 6 definite cases and in the Heidelberg series 4 definite cases of disseminated sclerosis among the relatives. Later, in 1937, with Speer, he described 2 further families with multiple cases. They found one doubtful case in the 212 parents and 4 definite, and 1 doubtful case in the 444 siblings; 4 in 444 is equivalent to 90 per 10,000 and 40 times the incidence in the general population, based on the Swiss surveys (Bing and Reese, 1926; Ackermann, 1931). As a control group, Curtius investigated the 640 relatives of 56 patients with fractures and found no case of disseminated sclerosis. Mackay (1950) reviewed the literature and, after careful consideration of the case reports, accepted 79 families with multiple cases of disseminated sclerosis. He added a further 5 families. He also found that up to and including 1948, autopsy confirmed the diagnosis in 3 patients in one family, in both patients in 4 families, and in one of two patients …