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Systemic juvenile idiopathic arthritis 'genetically distinct from other forms'

Published on 09 December 2016
Systemic juvenile idiopathic arthritis 'genetically distinct from other forms'

A new study has uncovered evidence that systemic juvenile idiopathic arthritis (JIA) should be considered genetically distinct from other types of JIA in a number of important ways.

Partly funded by Arthritis Research UK and led by the US National Institutes of Health, the study has indicated that systemic JIA should be classified separately from other forms of the disease, with different approaches used to treat the disease.

A different genetic profile
Currently, the definition of JIA is used to encompass a range of arthritic diseases that manifest during childhood, with systemic JIA - which, as the name suggests, results in systemic inflammation affecting multiple parts of the body - known as one of the rarer subtypes, leading to more severe outcomes.

Despite the unique clinical features of this disease, treatment strategies often involve using the same drugs as those used for other forms of JIA. This new study - which was published in the Annals of the Rheumatic Diseases - suggested this may not be the best approach.

Genome-wide research involving 770 children in nine countries was carried out, revealing two regions with variants that were increased in frequency in patients with systemic JIA, as well as 23 regions with suggestive association.

Importantly, none of the genetic associations identified were comparable to those found in other subtypes of JIA, with no evidence of any shared genetic risk factors.

The need for a new approach to treatment
This demonstrates that systemic JIA is a unique condition that is different from other forms of JIA - not just in terms of its symptoms and effects, but at a fundamental genetic level.

Understanding this will give researchers a firmer basis for future studies of the disease, allowing them to get a better grasp of the processes involved and potentially develop more effective new therapies.

The researchers concluded: "The lack of shared genetic risk factors between systemic JIA and other JIA subtypes supports the hypothesis that systemic JIA is a unique disease process and argues for a different classification framework.

"Research to improve systemic JIA therapy should target its unique genetics and specific pathophysiological pathways."

Arthritis Research UK's view
Dr Natalie Carter, head of research liaison and evaluation at Arthritis Research UK, said: "Around 15,000 young people and children live with the painful group of conditions called juvenile idiopathic arthritis. This study is very important, as it brings us closer to understanding one of the more severe subsets of JIA. It is imperative that we now start to consider systemic JIA as a unique disease with its own specific disease mechanism.

"As a charity, we are committed to funding exceptional science, including funding our specialised Arthritis Research UK Centre for Adolescent Rheumatology. We are hopeful that these results will lead to unique novel therapies."

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