MONDAY, June 30 (HealthDay News) -- Researchers have identified 21 new genetic regions implicated in Crohn's disease, bringing to 32 the total number of genes and loci -- regions of the genome typically including one or more genes that are known to increase susceptibility to the disease.

For this study, published in the journal Nature Genetics, the international team of scientists and clinicians analyzed DNA samples from almost 12,000 people in Europe and North America.

"We now know of more than 30 genetic regions that affect susceptibility to Crohn's disease. These explain only about a fifth of the genetic risk, which implies that there may be hundreds of genes implicated in the disease, each increasing susceptibility by a small amount," lead author Dr. Jeffery Barrett, of the Wellcome Trust Centre for Human Genetics at the University of Oxford, said in a prepared statement.

"Whilst this study shows the power of genome-wide association studies to reveal the genetics behind common diseases, it also highlights the complexity of diseases such as Crohn's," Barrett noted.

Crohn's disease causes inflammation of the gastrointestinal tract, resulting in pain, ulcers and diarrhea. Onset of the disease typically occurs between the ages of 15 and 40, but it can strike at any age. As many as 80 percent of people with Crohn's disease will require surgery.

Along with identifying potential new targets for the development of drugs to treat Crohn's, this study found that loci with genes associated with Crohn's are also implicated in a number of other diseases such as asthma, diabetes, rheumatoid arthritis and psoriasis.

"It's too early for us to say how Crohn's disease and many of these other diseases, including asthma, are linked at a biological level," study co-author Dr. Miles Parkes, consultant gastroenterologist at Addenbrooke's Hospital and the University of Cambridge, said in a prepared statement. "However, we are building up a picture of the biology underlying Crohn's disease, and the more we understand about the underlying biology of these diseases, the better equipped we will be to treat them."

"Genetics, and particularly the large scale approach of genome-wide association studies, offers much hope for understanding the biological causes of complex diseases," Dr. Mark Walport, director of the Wellcome Trust, said in a prepared statement. "Studies such as this also highlight the important relationships between different diseases, and, as such, may offer valuable insights into the pathways that lead to common symptoms such as inflammation."

The Wellcome Trust is a charity that funds biomedical research.

More information

The U.S. National Institute of Diabetes and Digestive and Kidney Diseases has more about Crohn's disease.