Scientists have discovered gene expression differences that could lead to better ways to classify, predict outcome, and treat juvenile idiopathic arthritis (JIA). Eventually such findings could enable doctors to target more aggressive treatment to children at risk of more severe arthritis, while those likely to have milder disease could be spared the stronger treatments that carry a greater risk of side effects. The researchers were supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), a part of the National Institutes of Health.
JIA is an inflammatory and sometimes disabling joint disease that affects an estimated 294,000 children in the United States. At present, making a diagnosis of JIA is imprecise and based largely on the presence of joint inflammation persisting for at least six weeks, for which no other cause can be determined, says Robert A. Colbert, M.D., Ph.D., chief of the NIAMS Pediatric Translational Research Branch. Based on the number of joints involved and other clinical features (fever and rash, for example), doctors classify patients into one of four or five major subtypes of JIA, which helps them predict a patient’s most likely outcome and guide appropriate treatments. "But, recent research suggests there is more variability in JIA than the four or five major subtypes we currently recognize," Dr. Colbert says.
In the first of two such NIAMS-supported studies to be published in the July issue of Arthritis & Rheumatism, scientists led by Michael Barnes, Ph.D., of Cincinnati Children’s Hospital Medical Center used a large data set to compare a number of children newly diagnosed with one of four major subtypes of JIA – persistent oligoarthritis (affecting four or fewer joints), polyarthritis (affecting five or more joints), systemic arthritis (with fever and rash and inflammation throughout the body) and enthesitis-related arthritis (affecting the junctions between tendons and bones). Using gene expression technology – a method by which scientists can determine the relative levels of expression of thousands of different genes at the same time and compare a pattern from one subject with another – the researchers looked for differences in the children’s blood samples that corresponded with the different forms of JIA.