March 19, 2010 -- Fifteen newly identified genes may offer a better understanding of the cause of ulcerative colitis and its ties to Crohn’s disease.
Two new studies involving more than 23,000 people bring the total number of genes associated with the painful disorder to nearly 30 and show at least half of these genes are also linked to Crohn’s disease.
“It is clear from these and other data that ulcerative colitis and Crohn’s disease share some mechanistic pathways and susceptibility genes, but that some pathways and genes are particular to each condition,” researcher Dermot P.B. McGovern, MD, PhD, of Cedars-Sinai Medical Center, and colleagues write in Nature Genetics.
Researchers say the discovery of these additional genes may help explain why the symptoms and severity of ulcerative colitis vary so dramatically from person to person. Understanding these individual differences may eventually lead to more effective and personalized treatments.
Ulcerative colitis and Crohn’s disease are the most common forms of inflammatory bowel disease. Ulcerative colitis usually affects only the colon and rectum; Crohn’s disease may affect any part of the digestive tract.
Ulcerative colitis and Crohn’s disease can cause symptoms such as abdominal pain, bloody diarrhea, and bleeding from the rectum.
Researchers say Crohn’s disease is more likely than ulcerative colitis to run in families.
New Genetic Ties for Ulcerative Colitis
In the first study, researchers combined results from previous genetic scans of 2,693 people with ulcerative colitis and 6,791 healthy people with a new analysis of genetic information from another set of 2,009 people with the disease and 1,580 healthy people.
The results highlighted 13 new genetic mutations associated with ulcerative colitis and confirmed 14 previously identified genes associated with the condition.
The second study identified two additional genes linked with an increased risk of ulcerative colitis in 1,043 German people with ulcerative colitis and a comparison group of 1,703 without the condition. Those results were then confirmed in another group of 2,539 people with ulcerative colitis and 5,428 healthy people.
Researchers say about half of the known genes associated with Crohn’s disease are shared with ulcerative colitis.
Although the findings increase the understanding of the cause of ulcerative colitis, researchers say there is still a long way to go.
“Taken together, our findings explain less than 10% of the variance of ulcerative colitis, and the challenge now is both to identify additional genetic factors and to translate these advances into real benefits for individuals with ulcerative colitis,” write McGovern and colleagues.