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Media Release: Having siblings reduces likelihood of juvenile arthritis

Having siblings is associated with protection against juvenile arthritis, a new study by Murdoch Children's Research Institute has found.

Researchers found the risk of juvenile arthritis in a child with no siblings was twice as high as a child with siblings.  Juvenile arthritis is an immune disorder that affects around 6000 Australian children.

Researchers compared 302 children with juvenile arthritis to over 1000 children without arthritis and found a protective association with sibling exposure, especially for exposure to three or more siblings.  The study found a clear pattern of association emerged in which greater exposure to siblings by six years of age was associated with a reduction in juvenile arthritis risk. Exposure to younger siblings appeared particularly important.

The finding suggests that increased microbial exposure in childhood may protect against the development of juvenile arthritis.

Lead researcher, Dr Justine Ellis said the findings provide further support for a role of the ‘hygiene hypothesis’, in combination with genetic factors, in the development of juvenile arthritis.

The genetic makeup of juvenile arthritis is becoming clearer, with 17 genes now associated with disease risk.  However, until now evidence for environmental risk remained sparse,” Dr Ellis said. 

“Our study showed exposure in the first six years of life to siblings may decrease the risk of juvenile arthritis.  This could be due to the fact that contact with siblings may provide protection by exposing children to infections and germs and building an immune system less susceptible to the development of juvenile arthritis.”

There is increasingly more evidence to suggest gut bacteria plays a part in the development of disease, with Institute and other research finding links with early microbial exposure and asthma, allergy and multiple sclerosis. 

Researchers studied sibling exposure as the presence of siblings in the home is likely to increase exposure to childhood infections.