GiGa determines genetic culprits causing IBD

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In a study published in Nature last week, scientists from GiGa (ULg) examined the genome of 67,852 individuals and applied three statistical methods to zoom in on which genetic variants were actively implicated in inflammatory bowel disease (IBD).  From the studied regions of the genome associated with IBD, 18 could be pinpointed to a single genetic variant with more than 95 per cent certainty. These results form a basis for more effective prescription of current treatments for the disease, as well as the discovery of new drug targets.

More than 850,000 people suffer from IBD in Europe. IBD is a debilitating disease in which the body’ s own immune system attacks parts of the digestive tract. The exact causes of this disease remain unclear, and there currently is no cure.

To understand more about the genetics underlying IBD, researchers have conducted genome wide association studies and previously found hundreds of genetic variants linked to the disease. However, it was not certain which specific genes were actually implicated by those variants.

Jeffrey Barrett (Wellcome Trust Sanger Institute) said: “We have taken the biggest  data set for IBD and applied careful statistics to narrow down to the individual genetic variants involved. Now we have a clearer picture of which genes do and do not play a role in this disease. We are zooming in on the genetic culprits of IBD.”

This genetic analysis enabled scientists to see which genetic variants directly influence the disease, and to separate them from other variants, which happen to be located near each other in the genome.

Hailiang Huang (Massachusetts General Hospital and Broad Institute) said: “An issue with studying complex diseases is that it can be hard to move from genetic associations, usually including many genetic variants of similar evidence, to knowing exactly which variants are involved. We need to be careful to depict the right variant. This new technique helps us to pinpoint which genetic variants are implicated in IBD with greater confidence.”

Michel Georges, (professor at GIGA, University of Liège) said: “These results will help towards rational drug discovery for complex human diseases like IBD, and possibly for the development of personalized medicine by finding biomarkers for more effective prescription of existing drugs.”

Hailiang Huang et al. (2017) Fine-mapping inflammatory bowel disease loci to single variant resolution. Nature. DOI: 10.1038/nature22969