A new gene has been linked to the appearance and development of Crohn's disease, an illness that affects around 500,000 people in North America each year. The gene, dubbed Atg16L1, increases the chances of the carrier developing the disease considerably, but it is not a direct cause. In fact, more than 30 areas in the human DNA are thought to be responsible for increased risks of Crohn's disease developing. Scientists at the Washington University School of Medicine in St. Louis say that finding all of these areas is essential in developing new, better treatments in the future.
 

Until now, doctors believed that this inherited disease evolved due to malfunctions of the immune systems, which was thought to attack some healthy cells in the gut, causing ulcerations and swelling. But a new study on lab mice showed that the Paneth cells, responsible for immune protection in some portions of the small intestine, lose their ability to develop a suited immune response to threats after the Atg16L1 gene mutates. According to Ken Cadwell, Ph.D., a postdoctoral student working in the study, "When they have less Atg16L1, the Paneth cells survive, but their ability to secrete granules is significantly impaired."
 

Herbert W. "Skip" Virgin, M.D., Ph.D., head of the Department of Pathology and Immunology at the Washington University says that outside, environmental factors are also crucial in determining the underlying causes of Crohn's disease. Following his study, new questions were raised concerning the degree at which Paneth cells affect the development of the disease and how other mutant genes affect the Paneth cells. The only certain result is that these cells indeed predispose a person to Crohn's disease.
 

Ellen Li, M.D., Ph.D., and Thaddeus Stappenbeck, M.D., Ph.D., co-authors and practitioners at Barnes-Jewish Hospital, gathered samples from patients they operated on over the years, in an attempt to discover all gene mutations that favor the appearance of the disease. The presence and concentration of the Atg16L1 gene was, in Virgin's own words, strikingly similar to that of the same gene in lab mice the researchers had under scrutiny during the study. This proves without a doubt that indeed the gene plays some role in the development of Crohn's disease and scientists are now trying to determine what this role is exactly.