Inflammatory bowel diseases in Indo-Canadians with and without antineutrophil cytoplasmic autoantibodies

A sequentially evaluated cohort of Indo-Canadians with either ulcerative colitis or Crohn's disease were prospectively examined for antineutrophil cytoplasmic autoantibodies (ANCA). Of 84 patients, 62 had ulcerative colitis and 22 had Crohn's disease. About one-third were born in Canada, and two-thirds were migrants from India or other countries, particularly East African nations. There was a disease-based and geographically based male predominance. The mean age of Canadian-born patients was significantly less than that of those born in other countries. Moreover, for migrants, the mean duration of residence in Canada before developing disease was 8.9 years for Crohn's disease patients and 13.5 years for ulcerative colitis patients. Moderate to severe disease was present; virtually all those with Crohn's disease had colonic involvement, and most of those with ulcerative colitis had extensive colonic disease. Overall, 40 of 84 (48%) were seropositive for ANCA, including a majority of those with ulcerative colitis but not Crohn's disease. In addition, eight had cytoplasmic ANCA, a reported seromarker for extensive colitis. Seropositive and seronegative patients were similar in age, sex, birth or duration of residence in Canada, site and severity of disease, familial history and complications, including pouchitis. This study supports the view that these diseases arise in individuals with a genetic predisposition following exposure to some, as yet unknown, environmental factor.