FAMILIAL CLUSTERING OF MULTIPLE-SCLEROSIS IN A NORTHERN SWEDISH RURALDISTRICT

A small rural district in the most northerly province of Sweden was fo und to have a very high occurrence of multiple sclerosis. A total of 1 2 patients with multiple sclerosis among 4744 inhabitants were identif ied (five females, seven males), corresponding to a prevalence of 253/ 100 000. Many of the patients were related and a further 21 cases with multiple sclerosis (14 females, seven males), mostly living in the ne ighbouring area, have family ties to the district. A genealogical inve stigation showed that 22 of the 33 patients identified had ties of kin ship and thus, to our knowledge, the largest aggregation of multiple s clerosis in a family is presented.