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

A sequentially evaluated cohort of Indo-Canadians with either ulcerative co litis or Crohn's disease were prospectively examined for antineutrophil cyt oplasmic autoantibodies (ANCA). Of 84 patients, 62 had ulcerative colitis a nd 22 had Crohn's disease. About one-third were born in Canada, and two-thi rds were migrants from India or other countries, particularly East African nations. There was a disease-based and geographically based male predominan ce. The mean age of Canadian-born patients was significantly less than that of those born in other countries. Moreover, for migrants, the mean duratio n of residence in Canada before developing disease was 8.9 pears 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 ha d colonic involvement, and most of those with ulcerative colitis had extens ive colonic disease. Overall, 40 of 84 (48%) were seropositive for ANCA, in cluding a majority of those with ulcerative colitis but not Crohn's disease . In addition, eight had cytoplasmic ANCA, a reported seromarker for extens ive colitis. Seropositive and seronegative patients were similar in age, se x, birth or duration of residence in Canada, site and severity of disease, familial history and complications, including pouchitis. This study support s the view that these diseases arise in individuals with a genetic predispo sition following exposure to some, as yet unknown, environmental factor.