Everyone is born with a certain genetic susceptibility for IBD, we believe the following exposure to environmental risk factors in a Western lifestyle and living environment can reach a certain threshold, after which IBD is developed. This can also explain the relatively low concordance rate in twin studies. In this theory, the coherent effect of all environmental exposures from neonatal period to death, named as the exposome by Wild, plays an important role.15 Future studies should focus on measuring this exposome, either through biomarkers or questionnaires in a longitudinally manner, yielding the possibility of combining all involved environmental risk and protective factors in an exposome risk score. This way, coherence of different factors is used, offering a more complete model of exposures. Also, the exposome risk score could now be combined with the already existing genetic risk score, for a more comprehensive model of disease than ever before.6,7 Also, the role of the exposome in disease course remains mostly unclear and should be explored next.
In contrast to genetic susceptibility, environmental exposures can be influenced actively. Therefore, the exposome is also of clinical value in multiple ways. First of all, as a preventive tool. Families with known genetic IBD susceptibility could be educated about the role of the exposome and its factors, because adaptation of lifestyle might delay or even prevent IBD development, as our suggested exposure threshold might not be reached. Secondly, knowing which environmental exposures are not only involved in development, but also course of disease by increasing chances of disease flare and development of complications, gives you the opportunity to not only treat patients with established disease by medication, but also by environmental exposure changes, leading to a more personalized treatment plan and possibly less need of medications in the future.8 Extensive studies are needed to compare the incidence of environmental exposures between patients with IBD and healthy controls, as well as to determine its role in disease course.
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