In a new, unprecedented study, researchers discovered that the genomic region underlying individuals’ susceptibility to inflammatory bowel disease (IBD) is conserved throughout populations around the world.
Researchers analyzed 10,000 DNA samples from people of East Asian, Indian or Iranian descent, together with 86,640 samples from across Europe, North America and Oceania. The study was conducted as part of the International IBD Genetics Consortium.
These findings, beyond the academic interest, have a strong potential impact on IBD therapeutics, since it shows that the underlying genetic causes for IBD are the same among populations and so a drug developed under the genetic studies of a particular population has the potential to also work in other populations.
Dr. Carl Anderson, study corresponding author at the Wellcome Trust Sanger Institute commented, “The prevalence of IBD has increased dramatically in Asia over the last 50 years, probably due to lifestyle changes brought about by economic growth. We are now able to compare genetic risk profiles of IBD across diverse populations to find out how similar they are. Discovering differences can provide us with biological insights that would be missed if we were to focus our efforts on just a single population. In turn, this can lead to the identification of new drug targets. In our study we found little difference in the genetic risk of IBD across the populations we studied. This is a very important finding because it suggests that biological lessons learned by studying the genetics of IBD will be relevant globally.”
While previous studies had already identified 163 genetic variants associated with IBD, these studies were performed with a majority of European individuals samples. The new study included 10,000 non-European samples (together with the European one’s) and scientists identified 38 new regions within the genome that influence susceptibility to IBD.
Dr. Jimmy Liu, study first author at the Sanger Institute noted, “We’ve already seen the benefit of using trans-ethnic approaches to understand complex diseases such as type-2 diabetes and rheumatoid arthritis. This study demonstrates the importance of collecting trans-ethnic data on IBD, firstly because any increase in the number of samples improves our ability identify regions of the genome influencing disease risk, and secondly because we can gain new insights into the biology underlying IBD by comparing results across the diverse populations.”
Although there is a common conservation of genetic variants between populations, the study also confirmed previously identified differences in IBD risk between European and non-Europeans – variants n the gene NOD2, previously associated with an increase in IBD risk only in Europeans (that are complete absent in Asian populations); variants in the gene TNFSF15 were found in both Europeans and East Asians, however only associated with an increase risk in East Asia populations.
Dr. Rinse K Weersma, at University Medical Center Groningen and also a study corresponding-author added, “This study is testimony to the need for large-scale international collaborations that enable us to answer questions that would not be possible using samples drawn from a single population. We thank every individual who donated a DNA sample to the study and the clinicians within the International IBD Genetics Consortium who collected these, particularly those outside of the US and Europe. The finding that the biology underlying IBD is consistent across populations is hugely important, it tells us that we can use insights from genetic studies of IBD to develop globally relevant drugs with the potential to improve disease management around the world.”