Researchers Decode Genetic Variation Associated With Type 1 Diabetes
Findings could lead to more efficient treatment, earlier detection of diabetes
Diabetes is the seventh leading cause of death in the United States, and some 215,000 Americans younger than age 20 have diabetes, according to the Centers for Disease Control and Prevention. Most cases of diabetes among children and adolescents are Type 1, which develops when the body can no longer make insulin, a hormone that controls the amount of blood glucose. Scientists now know that a patient’s inability to make insulin is caused by an abnormal immune system, but want to be able to predict and understand the way this disease starts.
Now, researchers from Benaroya Research Institute at Virginia Mason (BRI) and Seattle Children’s Research Institute (SCRI) have identified new clues as to how a common genetic change in a gene called PTPN22 may predispose children and adults to develop autoimmune conditions including Type 1 diabetes, rheumatoid arthritis and systemic lupus. The study was published in January 2012 in The Journal of Immunology and selected by the editors as one of the highlights of the issue.
Five to 15 percent of Caucasians in the United States carry the specific genetic change that was studied. The research focuses on how this change impacts the immune system.
Jane Buckner, MD, Associate Director at BRI, and David Rawlings, MD, Director of the Center for Immunity and Immunotherapies at SCRI, and their colleagues, studied a type of white blood cells known as B cells, and detected unusual types of problems in the development of these B cells in people who carry this specific genetic change. Since B cells make antibodies, proteins that are used by the immune system to function normally, the authors suggest that the developmental problem from this genetic change leads to an increased likelihood of producing B cells and antibodies that contribute to autoimmune diabetes.
“This work is an example of how we can apply a vast amount of genetic knowledge to advance our understanding of the causes of autoimmune diseases,” says Dr. Buckner. “In addition, it is an example of how collaboration, in this case between BRI and SCRI, can accelerate scientific discovery.”
Identifying associated changes in the function of immune cells can help scientists learn more about people who are at risk for autoimmune conditions.
Researchers involved in a recent worldwide clinical trial at 15 medical centers, including BRI, found that injections of the drug rituximab (also known as Rituxin) which is used to eliminate B cells, can slow the destruction of insulin-producing cells in some patients with Type 1 diabetes. Drs. Buckner and Rawlings and their teams will now follow up on that study, investigating what happened with the children treated in that clinical trial and whether the changes they have identified may predict a better response. They will also look into whether the same immune abnormalities can be observed before children develop diabetes. As part of the continued research, the team will study system models of the identical genetic change at SCRI, in parallel with the study of samples from patients and controls in repositories at the BRI.