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Juvenile arthritis likely a combination of genes and environmental factors

Research News
Friday, January 30, 2015 - 4:00pm
Melbourne scientists are on the brink of unravelling the complex causes behind juvenile arthritis, a debilitating but poorly understood disease similar to arthritis in adults.

It is likely that a combination of genes and environmental factors increase the risk of developing Juvenile Idiopathic Arthritis (JIA), according to researchers Dr Justine Ellis and Dr Jane Munro from the Murdoch Children's Research Institute.

JIA affects up to four in every 1000 Australian children aged between six months and 16 years old. Usually only a few joints are affected. But some children develop severe symptoms in multiple joints. The eyes, skin and muscles can also be involved in serious cases.

Many children grow out of the disease but for a minority it can result in permanent joint damage and disability.

“Very little is known about the causes of JIA, but we do know that genes and the environment play important roles,” says Dr Ellis, the leader of the Genes, Environment and Complex Disease Research group at the Institute.  

“There are many studies looking at the genetics of immune disorders such as arthritis, but the rise in incidence of immune disorders over the last two decades tells us that something else, some change in the environment, must also be at work.”

Dr Ellis says her research, which has been underway for the past five years, has uncovered new risk factors for JIA.

“Via international collaborations, we have identified a new gene for JIA,” Dr Ellis says.

“Our early preliminary data might also suggest that levels of vitamin D, in combination with certain genes, may increase the risk of developing JIA.”

“We are the only research group in the world collecting such detailed information about the environment on children with JIA.

 “Our hope is that our research will pave the way towards better treatments that address the root cause of the disease. We can then do a better job at limiting the long-term damage that JIA can do.”

The research,’ ChiLdhood Arthritis Risk factor Identification sTudY’, or CLARITY, is underpinned by a growing bank of biological samples, clinical and environmental data collected from hundreds of children with JIA and healthy children. The goal is to collect 2000 samples in total.

Each child in the study donates a blood sample which is analysed for genes, immune system molecules and other substances suspected to play a role in the development of JIA.

Families also complete a questionnaire about events during pregnancy, the early life of the child, and around the time of diagnosis.

By comparing genetic sequences and environmental exposures between children with JIA and healthy controls, differences between the two groups can be identified which helps the researchers close in on the combinations of genes and environmental factors that increase a child’s risk of developing JIA.

The data collected is an important resource which could contribute to understanding other autoimmune diseases including type 1 diabetes and inflammatory bowel disease.  

The information is being used in a new study investigating the link between cardiovascular and inflammatory diseases and discussions are underway to use it in other projects aimed at improving child health.