Ulcerative colitis is caused by inflammation in the intestines
Genetic variations which predispose people to a common inflammatory bowel condition have been uncovered by a team of German and UK researchers.
It was known that ulcerative colitis, which affects around 100,000 people in the UK, runs in families.
Now researchers have linked the condition with the gene that encodes for interleukin 10 (IL10) - a compound which regulates inflammation.
IL10 therapy has been tested in early studies, Nature Genetics reported.
Ulcerative colitis normally appears in people aged 15-30 and symptoms include bloody diarrhoea, abdominal pain, a frequent need to go to the toilet and weight loss.
Although symptoms can be mild, it can kill in severe cases if surgery is not performed in time.
Individuals with first-degree relatives who are affected are known to be at higher risk, but the individual genes involved had not been determined.
In the latest study, scientists scanned the whole genome in more than 1,000 people with the condition and 800 healthy controls.
Among a few gene differences, they found key variations in genetic regions directly alongside the IL10 gene.
Some early studies, mainly in mice, have already looked at IL10 for colitis therapy but negative findings had prompted researchers to look elsewhere.
"In light of these results, systemic or topical delivery of IL10 should be worthy of consideration for clinical trials," said study leader Professor Stefan Schreiber.
He added that further research on this area of the genome in colitis patients may point to as yet unknown drug targets.
The administration of interleukin 10 to individuals with colitis has been reported to have a positive effect in initial studies, although this potential therapy has not been assessed more thoroughly.
Professor Jack Satsangi a gastroenterology expert at the University of Edinburgh said previous research on IL10 as a treatment had focused on another inflammatory bowel condition, Crohn's disease.
"It may be that it didn't work in Crohn's disease but it's worth pursuing in ulcerative colitis," he said.
"There are also issues about whether it should be delivered systemically - orally, intravenously - or directly into the gut.
"There is certainly an unmet need for treatments so there is mileage in this."
Professor Jonathan Rhodes, an expert in colitis based at the University of Liverpool, added that the study would help to unpick what was causing the condition - at least in some patients.
"It makes much firmer the hypothesis that there is an underlying defect in the immune system," he said.