Inflammatory bowel disease in a Swedish twin cohort: a long-term follow-up of concordance and clinical characteristics.
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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ABSTRACT: The recent molecular advances in the understanding of the genetics of inflammatory bowel disease (IBD) have their grounding in studies examining IBD within different family groups and populations. The risk of IBD is highest in first-degree relatives of an IBD proband but more distant relatives are also at increased risk. The risk is higher for relatives of a CD proband. The risks of developing IBD for ‘high-risk’ relatives might be as great as 1 in 3 but in general first-degree relatives have a 1 in 10–20 risk. Three recent systematic studies have identified a total of 326 European twin pairs to examine disease concordance rates. The derived heritability in Crohn's disease is greater than for many complex diseases and is currently under detailed examination. Strong concordance has been shown, in particular for disease type and disease location, in multiplex families and twin studies. More than 75% children are diagnosed with IBD at a younger age than their parents but true genetic anticipation appears unlikely.Baillière' s Best Practice and Research in Clinical Gastroenterology 06/2004; 18(3):525-539. · 3.28 Impact Factor
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ABSTRACT: The pathogenesis of inflammatory bowel diseases (IBD), such as ulcerative colitis (UC) and Crohn’s disease (CD) is complex, and our knowledge on the topic is constantly growing. The two disorders are distinct, yet overlap in their clinical manifestations and underlying causes. This review aims to provide a broad overview of the numerous pathogenetic factors that can lead to the development of IBD, focusing on novel findings and on the differences between UC and CD. Recent advances in genetics have identified new components in the pathogenesis, as an example, the importance of Th17 lymphocytes and the IL-17/IL-23 pathway have been highlighted in both diseases, apart from the previously known Th1-Th2 driven processes. Genetic background of increased permeability has been explored in UC, and the role of defective autophagy was recently described in CD. Genetic alterations can lead to an exaggerated immune response to the resident microbial flora. This microflora is altered in IBD patients, probably due to their reduced ability to stabilize its bacterial components and due to different environmental factors. An exhaustive exploration of environmental factors is particularly important, as they can be influential in many cases. The impact of smoking is the most established environmental factor, having deleterious effects in CD and protective in UC. Recent opinions on other factors, such as early appendectomy, diet, reduced vitamin D levels, the use of specific medications, breastfeeding, personal hygiene and psychological factors are also discussed. Epigenetics, a new field of research, links environmental factors to genetics. Understanding these factors is of great significance as changing lifestyles and improving life circumstances have started to increase the prevalence of IBD also in developing countries.Journal of Clinical and Cellular Immunology. 09/2014; 2014(5):253.