Around 29 genome regions have been linked with ulcerative colitis by researchers. The latter is a common form of inflammatory bowel disease (IBD).
The new findings support the theory that an overactive immune response to the natural bacteria found in the gut could play a role in the condition.
"The outcomes and quality of life for patients with ulcerative colitis can be bleak," said John Rioux from the Montreal Heart Institute and senior author on the paper.
"To understand the genetic causes of the disease, we carried out the largest study of the disease to date - taking a magnifying glass to over one million sites in the genomes of more than 26,000 people," he said.
The team carried out a genome-wide scan to look for changes in the genetic code common to patients with ulcerative colitis.
They did this by looking at genetic data from more than 32,000 apparently healthy people, and more than 16,000 people suffering from ulcerative colitis.
Using the technique, the team homed in on 29 new regions that are associated with the disease - bringing the total number for ulcerative colitis to 47 and the total for inflammatory bowel disease to 99.
The genetic regions identified act like signposts, pointing to a number of suspect genes that might play an important role in ulcerative colitis.
"The genomic regions we have identified give us an insight into the biology underlying ulcerative colitis," said Carl Anderson from the Wellcome Trust Sanger Institute and first author on the paper.
"These important initial discoveries are the building blocks on which we can begin to derive better IBD treatments, though much further work is needed before these become a clinical reality," he said.
"To give us a better understanding of IBD biology, we compared the results of this ulcerative colitis study to those of a similar study we recently completed looking at Crohn's disease, and the results were very informative," he added.
The team found significant overlap between the genetic regions associated with each disease, with at least 19 of the total 47 ulcerative colitis regions also associated with Crohn's disease.
They showed that many of the overlapping regions include genes involved in expanding and maintaining a group of T-cells involved in our immune response.
They now hope the new discoveries will open the door to further research and new treatments.