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World J Gastroenterol. Feb 7, 2014; 20(5): 1238-1247
Published online Feb 7, 2014. doi: 10.3748/wjg.v20.i5.1238
Epidemiological studies of migration and environmental risk factors in the inflammatory bowel diseases
Yanna Ko, Rhys Butcher, Rupert W Leong
Yanna Ko, Rhys Butcher, Rupert W Leong, Concord Hospital, Gastroenterology and Liver Services and The University of New South Wales, Sydney NSW 2139, Australia
Author contributions: Ko Y contributed to this work, performed the literature review and the literature review, and analysed the data; Leong RW designed the research; Ko Y, Butcher R and Leong RW wrote the paper.
Supported by A Career Development Fellowship of the National Health and Medical Research Council of Australia to Leong RW
Correspondence to: Rupert W Leong, MBBS, MD, FRACP, AGAF, Associate Professor, Concord Hospital, Gastroenterology and Liver Services and The University of New South Wales, Level 1 West Hospital Rd, Concord, Sydney NSW 2139, Australia. rupertleong@outlook.com
Telephone: +61-2-97676111 Fax: +61-2-97676767
Received: July 17, 2013
Revised: November 27, 2013
Accepted: January 2, 2014
Published online: February 7, 2014
Abstract

Inflammatory bowel diseases (IBD) are idiopathic chronic diseases of the gastrointestinal tract well known to be associated with both genetic and environmental risk factors. Permissive genotypes may manifest into clinical phenotypes under certain environmental influences and these may be best studied from migratory studies. Exploring differences between first and second generation migrants may further highlight the contribution of environmental factors towards the development of IBD. There are few opportunities that have been offered so far. We aim to review the available migration studies on IBD, evaluate the known environmental factors associated with IBD, and explore modern migration patterns to identify new opportunities and candidate migrant groups in IBD migration research.

Keywords: Inflammatory bowel disease, Crohn’s disease, Ulcerative colitis, Epidemiology, Risk factor, Environment, Hygiene hypothesis

Core tip: Inflammatory bowel diseases (IBD) are well known to involve genetic and environmental risk factors. Cohorts from low IBD prevalence regions migrating to areas of high IBD prevalence are candidates to assess further environmental factors - both protective and promotional. There are few opportunities to identify migratory populations to highlight these effects of environmental risk factors in the development of IBD and to compare first- and second-generation migrants. This review highlights known migratory cohorts and identifies an emerging cohort in Middle Eastern migrants to Australia.