For years, rheumatologists debated the differences between rheumatoid arthritis and pediatric arthritis. A new study shows they may be more alike than believed.

Are rheumatoid arthritis and juvenile rheumatoid arthritis simply the same illness diagnosed at different life stages?

The answer isn’t as clear-cut as rheumatologists, patients, and researchers might think.

Juvenile arthritis (JA) — also known as juvenile rheumatoid arthritis, pediatric arthritis, and juvenile idiopathic arthritis — is the sixth most common childhood disease, but it’s often misdiagnosed or undiagnosed.

One reason for this is due to the misconception that “arthritis” only affects an older portion of the population. Another problem is the national shortage of pediatric rheumatology specialists.

There is also the issue that the umbrella term “juvenile arthritis” actually encompasses several unique childhood rheumatologic diseases.

Furthering the confusion surrounding JA is whether or not it is actually a separate and distinct disease from rheumatoid arthritis (RA) or if it is simply early-onset or pediatric RA, meaning, the same disease diagnosed at a younger age.

Read more: Get the facts on juvenile rheumatoid arthritis »

A new study may provide some clarity and guidance about the JA vs. RA conundrum.

In it, researchers say a genetic link has been found between JA and RA.

It was already known among pediatric rheumatologists that some kinds of juvenile idiopathic arthritis have adult counterparts.

Past research also showed that there was a genetic link between juvenile idiopathic arthritis and a chromosomal abnormality, but the sample sizes were weak.

In the new study, genetic associations within juvenile idiopathic arthritis categories were compared with adult inflammatory arthritis.

According to a press release about the study, “A major finding was that there were within-category associations for juvenile idiopathic arthritis. Specifically, the study team found that rheumatoid factor (RF)-negative polyarticular and oligoarticular were genetically similar. Comparisons with adult disease showed a shared association of human leucocyte antigen-DRB1 amino acid at position 13 for both child-onset and adult diseases. Moreover, researchers found that associations from a combined dataset for juvenile idiopathic arthritis types oligoarthritis and RF-negative polyarthritis were the same associations seen in adult seronegative rheumatoid arthritis.”

The authors of the study added, “The results of this study have important implications for understanding disease pathogenesis, aetiology, and potential future therapeutic strategies for JIA categories,” but they note that more genetic research will need to be done into JA.

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But it is possible that these findings may eventually provide better, more targeted novel treatment therapies for JA and RA patients alike.

Or at least may open up treatment options to JA patients who have been limited by the “juvenile” component of their diagnosis.

The report states that, “There are no specific therapeutic strategies for seronegative RA at this time, but given the rarity of this subphenotype of RA and the JIA categories individually, this study suggests that further comparisons of genetic studies for these diseases could help identify novel pathways and targets for therapy for both adult-onset and childhood-onset forms of inflammatory arthritis.”

According to an article in The Hospital for Special Surgery, “For more than 95 percent of the children with arthritis, we don’t need new drugs or miraculous inventions, we just need proper application of the resources we already have.”

But a missed JA diagnosis or delayed treatment can be catastrophic, as evidenced by recent reports out of the United Kingdom.

The same can be said for adult-onset RA.

Whether they share these genetic commonalities or not, both diseases are among the most disabling in their respective age demographic — and both can affect more than bones and joints.