It has been known for many years that inflammatory bowel disease tends to run in families and the risk of contracting this disorder is increased if one has a first degree relative suffering from the condition. More recently considerable effort has been made to discover genes which predispose to the development of IBD and it had been hoped that this information might improve our understanding of both Crohn’s disease and Ulcerative colitis and possibly indicate the form of treatment which is most likely to prove effective. There are considerable differences in the progress of IBD and an accurate prediction of its natural history has been extremely difficult. It was disappointing therefore to read a paper in the March 2014 issue of the American Journal of Gastroenterology in which a prospective group of patients with Crohn’s and Ulcerative colitis were followed up following genotyping with identification of 163 inflammatory bowel disease risk loci. The total genetic risk was calculated and associated with development of IBD.
The study group included 1105 patients (697 CD 408 UC) increasing genetic burden was associated with an earlier age of diagnosis of CD with patients in the highest quarter of the genetic burden likely to develop disease 5 years earlier than those in the lowest quarter. Increasing genetic burden was also associated with ileal involvement in CD. Genetic burden was stronger in subjects who had never smoked but the burden was not associated with the progress of disease in UC.
This work suggests that genetics is of limited value in predicting the natural history of IBD and hence may also be disappointing in helping the choice of treatment. Further investigations along this line are likely to be shortly forthcoming.
This article was first published on the original crohns.org.uk blog. Research has moved on since, so please check current advice with your IBD team.