Multiple sclerosis in American blacks.

In the period 1968 through 1977, multiple sclerosis (MS) was diagnosed in 349 patients at the Henry Ford Hospital. Of these 312 were accepted in the study and 53 were blacks. In this medical center where the overall population consists of approximately 50% blacks, the MS blacks comprised only 17% of the total MS population. White and black MS patients did not differ significantly for clinical characteristics of MS or for death rates. The MS black patients were divided in two groups, Northern- and Southern-born. The mean age of migration was 11.9 years. Southern-born blacks lived an average of 20 years in the North before the symptoms of MS began. Northern-born MS patients had a 5.5 earlier age of onset and the diagnosis was made 9 years sooner when compared with the Southern-born MS blacks. The Southern-born MS group more often showed a chronic progressive course wither initially or following a few exacerbations and remissions. These findings suggest that a possible genetic predisposition, as well as a geographically determined exposure to an environmental agent, may be related not only to the risk of developing MS, but in the American blacks may also influence the age of onset, the age of diagnosis, and even the clinical course of MS.