An international research group recently identified 14 new genes that are associated with juvenile idiopathic arthritis (JIA), and reconfirmed the link with three other genes connected to the disease.
Researchers say the discovery could open up new areas for research and treatment. “Previously we only knew about three genes linked to JIA, so to identify these additional 14 genetic risk factors is quite a big breakthrough,” says study co-author Joanna Cobb, PhD, research associate in the Arthritis Research UK Epidemiology Unit in the Manchester Academic Health Science Centre, The University of Manchester, in England. “Identifying the genes associated with JIA will help us understand what is causing JIA, how the disease progresses, and then to develop new potential therapies. This discovery may also help predict which children need special treatment earlier and allow health workers to better control pain, quality of life and long-term outcomes.”
The research, published online in Nature Genetics, also found an additional 11 genes that may have links to JIA as well. Cobb says this is the largest study to date of genetics in juvenile arthritis and credits the success of this study to a collaboration of scientists from around the world.
JIA affects almost 300,000 children in the United States. It is believed to be caused by a combination of genetic and environmental factors, but until very recently, little was known about the genes that are important in developing this disease.
The researchers performed genetic analyses on 2,816 children with JIA from 40 pediatric rheumatology clinics as well as 13,056 children without JIA who served as controls. The study focused only on genetic analysis of patients with two types of JIA that account for about 70 percent of all cases: oligoarthritis and rheumatoid factor negative polyarthritis. Oligoarthritis affects four or fewer joints after six months, and rheumatoid factor negative polyarthritis affects more than five joints.
Several of the genes that were identified in this study have also been found in other autoimmune disorders, including lupus and type 1 diabetes. The authors write they expect more genes associated with JIA risk will be found because the existing 17 genes explain only an estimated 18 percent of the risk for developing JIA.
The discovery of the genes shows that, from a genetic point of view, JIA is not just one disease, and therefore might have more diagnosis and treatment options, according to Jill Hollenbach, PhD, an assistant staff scientist at the Center for Genetics, Children’s Hospital Oakland Research Institute, in Oakland, Calif.
“It seems that different subtypes of JIA are associated with different genetic backgrounds [groups of genes],” she says. “The identification of these new genes may help researchers and doctors to further refine the way they diagnose the disease based on each patient’s genetic profile. Because the different subtypes of JIA may have different disease courses and treatments, earlier identification of disease subtype may allow doctors to determine the best course of treatment for an individual patient at a much younger age.”