A Defective Gene in Juvenile Arthritis

Arthritis is something at our age, we'll start to deal with but there's a form of arthritis that hits children called Juvenile idiopathic arthritis or JIA. They have chronic joint pain, swelling, stiffness, and in some cases fever, swollen lymph nodes and rash on the trunk of the body. These symptoms can last for months or for the rest of their lives. And, it can interfere with their bone development and damage joints.

It's unclear what causes this autoimmune disorder but the environment and genetics are suspected. A study is pointing to a gene that may be partly to blame. Researchers looked at twin girls who developed JIA at four and six. They learned the twins' grandmother had psoriatic arthritis and when scientists sequenced the twins' DNA, they found both girls carried a mutation in a gene that encodes a protein called NFIL-three. This mutation meant the encoded protein was unstable, only half the usual amount was made, and the protein didn't even work.

But NFIL-three is important in regulating immune responses. Mice deficient in it develop colitis, an inflammation of the large intestine. In people, one form of colitis is inflammatory bowel disease and it's caused by an abnormal immune response to environmental triggers. In these people, there are lower levels of the NFIL-three protein.

When researchers bred mice without the protein, the animals developed inflammatory arthritis much earlier than normal mice. This further suggests NFIL-three is partly responsible for JIA in children and creates a path for researchers to develop better therapies for these kids.