International study finds new genetic links to juvenile arthritis

Researchers report in Nature Genetics they have increased the number of confirmed genes linked to juvenile idiopathic arthritis (JIA) from three to 17 – a finding that will clarify how JIA fits into the spectrum of autoimmune disorders and help identify potential treatment targets.

Published April 21, the study involves an international research team that analyzed 2,816 JIA cases recruited from more than 40 pediatric rheumatology clinics. It was the largest collaborative patient population of JIA to date, including patient DNA samples from across the United States, Germany and United Kingdom, according to Susan Thompson, PhD, a researcher in the Division of Rheumatology at Cincinnati Children's Hospital Medical Center who was a leader for the study.

"These findings will help us understand how the long suspected genetic contributions to JIA are driving the disease process, with the ultimate goal being earlier and improved diagnosis and treatment," Thompson said.

JIA is the most common rheumatic disease of childhood that involves several different but related forms. Affecting some 50,000 children in the US, the actual cause of the disease remains unknown. JIA is considered an autoimmune disorder, in which the body's immune system mounts an attack against its own healthy tissues. JIA can be treated with medications and physical therapy, but the disease can persist for many patients into adulthood.

Prior to the current study only three genes were associated with known JIA risk, although scientists have suspected the likelihood that more genes are involved. The research team used what is known as the Immunochip array to measure variation in the genes (DNA) coding for components of the immune system for 2,816 JIA patients in the study. Those findings were compared to the DNA of 13,000 healthy controls to look for genetic differences.

The analyses re-confirmed JIA's connection to the original three genes, identified a link to the 14 new genes and pointed to the possibility that another 11 genetic regions may be implicated. The scientists stressed that their work continues in order to identify additional genetic links and also begin conducting functional studies to pinpoint disease processes.

It may begin with a swollen knuckle, a spiking fever, or an unexplained rash. But no matter what symptoms appear, hearing the word "arthritis" in a diagnosis for your child can be unexpected and confusing.

Arthritis is an inflammation of the joints that is characterized by swelling, heat, and pain. Nearly 300,000 children in the United States have some sort of arthritis. Arthritis can be short-term - lasting for just a few weeks or months, then going away forever - or it can be chronic and last for months or years. In rare cases, it can last a lifetime.

The most prevalent form of juvenile arthritis is juvenile idiopathic arthritis (JIA) (also known as juvenile rheumatoid arthritis, or JRA). It affects about 50,000 U.S. kids and is very different from adult rheumatoid arthritis.