News Release: Research
Mar. 29, 2011
NIH Awards Emory $4.8 Million to Study Genetics of Crohn's in African Americans
The National Institutes of Health has awarded Emory University $4.8 million over five years to study the genetics of Crohn’s disease in African Americans. The principal investigator is Subra Kugathasan, MD, professor of pediatrics (gastroenterology) at Emory University School of Medicine and Children’s Healthcare of Atlanta.
“This will be the first large-scale, genome-wide association study of Crohn’s disease in African Americans,” says Kugathasan. “Previous genetic studies of Crohn’s disease were done in people of European descent, and genome-wide association studies have been successful in identifying dozens of variations responsible for contributing to disease risk. Unfortunately, most of these variations are not expected to contribute to Crohn’s disease risk in African Americans. This is due to the genetic differences that exist between the two populations.”
Scientists expect that finding genetic variations linked to Crohn’s disease will help doctors find new treatments and better choose between existing treatments for patients with the disease. In contrast to other complex conditions in which genomic approaches have been disappointing, Crohn’s disease is “the poster child” for successful genomic studies, Kugathasan says.
Crohn’s disease is a type of inflammatory bowel disease, often episodic, that can involve abdominal pain, diarrhea, blood in the stool and weight loss. It is estimated that approximately 500,000 North Americans are dealing with Crohn’s disease. Severe cases lead to blockage of the intestines, requiring surgery to remove part of the intestines. Having Crohn’s also increases the risk of colorectal cancer.
There is no cure for Crohn’s disease, although it can be treated with various antinflammatory and immunosuppressant drugs. Doctors believe that the inflammation in Crohn’s disease comes from the immune system reacting against bacteria that are normally found in the intestines, and then being unable to turn the reaction off. Risk factors include family history, smoking, diet and environmental exposures.
Doctors have previously viewed Crohn’s disease as a condition predominantly affecting people of European descent. However, the number of reported cases in African Americans has been increasing, and more cases that were previously untreated because of disparities in health care are now being recognized, Kugathasan says.
“Future drugs for Crohn’s disease will be based on genetics, and more specifically tailored to the patient,” he says. “A greater understanding of genetics of Crohn’s in African Americans will complement existing studies and also provide population-specific information toward understanding, managing and treating the disease.”
Genomic studies of Crohn’s disease have already led to a shift in the field, with a greater emphasis on the bacteria that live in the gut and the genes that affect cells’ ability to recognize and respond to those bacteria, he says.
Kugathasan is scientific director of Children’s Combined Center for Pediatric Inflammatory Bowel Disease and an investigator in the Children’s Transplant Immunology and Immune Therapeutics Center, one of the priority centers established within the Emory-Children’s Pediatric Research Center.
For his clinical study he plans to recruit 1,500 patients with Crohn’s disease nationwide, along with 1,150 controls. Both pediatric and adult participants are eligible for the study. Top gastroenterologists at medical centers across the United States have pledged to recruit patients, he says.
Kugathasan will look for both single nucleotide polymorphisms (alternative spellings of one particular letter in someone’s genetic code) and copy number variations (longer duplications or deletions, whose detection is more complex) that contribute to Crohn’s disease risk in African-Americans.
At Emory, the investigators will collaborate with Michael Zwick, PhD, assistant professor of human genetics, who has developed “targeted sequencing” techniques for investigating the genetics of autism, and also with David Cutler, PhD, assistant professor of human genetics, who has developed techniques for large-scale genomic analysis.
This genomic study will cooperate with the ongoing Inflammatory Bowel Disease Genetics Consortium, which was created by the National Institute of Diabetes, Digestive and Kidney Diseases in 2002 and is headquartered at Yale University.