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Genetic loci for IBD risk similar in Europeans, non-Europeans
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Researchers have identified 38 new genetic loci associated with risk for inflammatory bowel disease, and found most known loci are consistent in European and non-European individuals.
“The prevalence of IBD has increased dramatically in Asia over the last 50 years, probably due to lifestyle changes brought about by economic growth,” Carl A. Anderson, PhD, from the Wellcome Trust Sanger Institute in the UK, said in a press release. “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.”
Previous studies have identified more than 163 genetic loci associated with IBD, but large scale research has only been performed using European cohorts. Anderson and colleagues therefore added 11,535 Europeans and 9,846 non-Europeans to their previously reported cohort of 75,105 exclusively European samples. They used genome-wide or Immunochip data from a total of 86,640 DNA samples from European individuals, and 9,846 DNA samples from people of East Asian, Indian or Iranian descent to identify new genetic loci associated with IBD and compare genetic effects on IBD risk across these different ethnic populations. They identified 38 new loci, and determined the majority of known risk loci were consistent across the European and non-European cohorts.
“In our study we found little difference in the genetic risk of IBD across the populations we studied,” Anderson said in the release. “This is a very important finding because it suggests that biological lessons learned by studying the genetics of IBD will be relevant globally.”
“We've already seen the benefit of using trans-ethnic approaches to understand complex diseases such as type-2 diabetes and rheumatoid arthritis,” Jimmy Z. Liu, PhD, also from Wellcome Trust Sanger Institute, said in the release. “This study demonstrates the importance of collecting trans-ethnic data on IBD, firstly because any increase in the number of samples improves our ability [to] 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.”
However, not all IBD risk loci were found to be consistent across different ethnic populations. Genetic variants in NOD2, for example, significantly affected IBD risk in Europeans (OR = 2.13-3.03) but were not present in East Asians. Two other signals at TNFSF15-TNFSF8 appeared with similar frequency across cohorts, but appeared to more significantly affect IBD risk in East Asians (OR = 1.75 and 1.7) compared with Europeans (OR = 1.15 and 1.14, respectively).
The researchers concluded that in this “first trans-ancestry association study of IBD,” the 38 risk loci detected increases known IBD risk loci to a total of 200, most of which are shared across diverse ethnic populations and collectively explain 13.1% of the variance in disease liability for Crohn’s disease, and 8.2% of the variance in ulcerative colitis.
“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,” Rinse K. Weersma, MD, PhD, from University Medical Center Groningen in the Netherlands, said in the release. “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.” – by Adam Leitenberger
Disclosure: The researchers report no relevant financial disclosures.
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