Article

Inflammatory bowel disease in a Swedish twin cohort: A long-term follow-up of concordance and clinical characteristics

Division of Gastroenterology, Department of Medicine, Orebro University Hospital, S-701 85 Orebro, Sweden.
Gastroenterology (Impact Factor: 13.93). 06/2003; 124(7):1767-73. DOI: 10.1016/S0016-5085(03)00385-8
Source: PubMed

ABSTRACT In 1988, we reported the first twin study in inflammatory bowel disease. The aim of the current study was to follow up these twins regarding new cases of inflammatory bowel disease and Crohn's disease characteristics using the Vienna classification.
The official Swedish population register and the cause of death register were used to search for the twins. All living patients were interviewed.
Three monozygotic twins earlier classified as healthy had been diagnosed with inflammatory bowel disease (ulcerative colitis, n = 2; Crohn's disease, n = 1). Retrospectively, all 3 were symptomatic at the original survey. This changed the pair concordance in monozygotic twins from 6.3% to 18.8% in ulcerative colitis and from 44.4% to 50.0% in Crohn's disease. A high degree of concordance regarding age at diagnosis, disease location at diagnosis and during the course, and disease behavior was found in concordant monozygotic twin pairs with Crohn's disease. Seven of 9 pairs were identical in 3 or more of these disease characteristics compared with an expected number of 1.5 (P = 0.000076).
This study confirms that the genetic influence is stronger in Crohn's disease than in ulcerative colitis. A remarkable phenotype similarity within concordant pairs with Crohn's disease was found using the Vienna classification.

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    • "This might be obvious in the context of the genetic association of XBP1 variants with IBD reported here, but we speculate that environmental factors may also impair XBP1 function (and hence the ER stress response). Monozygotic twin studies have highlighted the importance of as yet unknown environmental and/or epigenetic factors in the development of IBD (Halfvarson et al., 2003). One might speculate that microbial-or food-derived XBP1 inhibitors could interfere with the pathways described herein, particularly in a genetically susceptible host, thus contributing to the development of intestinal inflammation. "
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    • "For example, polymorphisms in pattern recognition receptors, such as CARD15/NOD2 that recognize microbial components, have highlighted the importance of the microbiota in pathogenesis of CD (Sartor et al., 2006). The genetic influence is also supported by higher concordance rates (approximately 50%) for CD occurrence in monozygotic twins (Halfvarson et al., 2003; Jess et al., 2005; Orholm et al., 2000; Tysk et al., 1988). Still, approximately 50% of identical twin pairs are discordant for CD (i.e. one is diseased and one is healthy) demonstrating that environmental factors are also important for disease incidence (Halfvarson et al., 2006; Loftus et al., 2004). "
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