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PHENOTYPIC CHARACTERISTICS OF INFLAMMATORY BOWEL DISEASE (IBD) IN FRENCH CANADIANS: COMPARISON WITH A LARGE NORTH AMERICAN REPOSITORY
M Bhat, G Nguyen, R Lahaie, E Bernard, C Deslandres, G Aumais, G Jobin, D Langelier, P Paré, G Wild, A Cohen, J Rioux, A Bitton
McGill University Health Center, University of Toronto, University of Montreal Genetic Research Center (UMGRC)
OBJECTIVE: Several mendelian genetic disorders have been described within the French-Canadian population of Quebec. However, IBD as a polygenic entity has never been appraised. The aim of this study is to determine whether a distinct phenotypic pattern exists in this population descended from a small number of founders.
METHODS: The UMGRC is one of 6 centers comprising the NIDDK-IBD consortium, which has been recruiting patients from different populations across North America. Using well-characterized phenotypic data in this repository on primarily adult IBD patients, we assessed the phenotypic characteristics of 148 French-Canadians from the UMGRC in comparison to those of 1328 other white patients. Patients were categorized as such only when atleast 3 out 4 grandparents were of French-Canadian origin. The following parameters were evaluated: diagnosis, anatomical location and disease behavior (inflammatory, stricturing or penetrating), extraintestinal manifestations, surgical history, and family history of IBD. The categorical characteristics of French-Canadian patients were compared to those of other whites using chi-square analysis or Fisher’s exact test of proportions.
Multiple logistic regression models were developed to isolate the independent effect of French Canadian ethnicity on the relative odds of penetrating and stricturing disease.
RESULTS: French-Canadian CD patients were more likely than other whites to develop fistulizing disease (41% vs 29%, p = 0.01), with odds ratio of 1.53 after multivariate adjustment. They were less likely to have stricturing disease (10% vs 21%, p = 0.003), with odds ratio of 0.41 after multivariate adjustment. There was an increased prevalence of sacroiliitis (4% vs 2%, p<0.05). French-Canadian UC patients were more likely to be smokers as well (36% vs 27%, p<0.01).
CONCLUSION: The increased prevalence of fistulizing disease among French-Canadians may herald the need for a more anticipatory approach to treatment of Crohn’s disease in this population. It would be of interest to analyze whether any underlying genetic variations account for this more aggressive disease behavior.