November 16, 2009

Gene Mutations Linked to Early-Onset Inflammatory Bowel Disease

photo of a young girl holding her stomach

An international team has discovered that mutations in either of 2 related genes cause a severe and rare form of inflammatory bowel disease in young children. The discovery allowed the researchers to successfully treat one of the study patients with a bone marrow transplant.

Inflammatory bowel disease is a group of disorders that includes Crohn's disease and ulcerative colitis. The inflammation, or swelling, of the intestines can cause pain, damage the tissue and make the intestines empty frequently, resulting in diarrhea. Previous studies have identified dozens of genes and variants that affect the risk for adult-onset inflammatory bowel disease, but none that singly cause the disease.

An international research team set out to search for genetic risk factors for early-onset inflammatory bowel disease. They examined DNA from 2 unrelated families with children who were affected by the disease. The research team, which was supported by several sources, included scientists from NIH's National Center for Biotechnology Information (NCBI), University College London in the United Kingdom, Hannover Medical School in Germany and several other institutions.

The scientists found that mutations in either of 2 genes are sufficient to cause early-onset inflammatory bowel disease, as reported in the advance online edition of the New England Journal of Medicine on November 4, 2009. Screening 6 additional patients with early-onset colitis identified another mutation in one of the genes. The 2 genes code for the proteins IL10R1 and IL10R2. These proteins act together to receive signals from interleukin 10, a signaling molecule that plays a crucial role keeping the body's inflammatory responses in check. When either IL10R1 or IL10R2 is mutated, the signals from IL10 cannot be received, and the resulting inflammation causes tissue damage, especially in the gastrointestinal system.

One of the young patients who hadn't responded to other therapies was given a bone marrow transplant from a healthy sibling. Bone marrow transplants can cure genetic disorders when the affected gene is normally active in marrow-derived cells. However, because of the risks associated with the procedure, the transplants are used only in cases of severe disease. This patient showed dramatic improvement following the procedure and has remained in remission from inflammatory bowel disease for more than a year.

"This is an excellent example of how discovery of causative genes and mutations can enable clinicians to go from bench to bedside for an informed treatment of patients," says Dr. Christoph Klein of Hannover Medical School, who led the diagnosis and treatment effort.

"This discovery is a milestone in research on inflammatory bowel disease, and will enable us to gain further insights into the physiology and immunity of the intestine," says Dr. Erik Glocker of University College London.

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