Narrator: This is Science Today. It's been known for decades that rheumatoid arthritis, which affects over two million people in the United States, is linked to genetics. But according to rheumatologist, Lindsey Criswell of the University of California, San Francisco, the question remains what triggers the disease in those with the genetic marker called DR 4?
Criswell: It turns out that having DR 4 on your cells in your body is very, very common. Yet, only a small percentage of those people go on to get rheumatoid arthritis. So that tells us that if you inherit DR 4 from one of both or your parents, you are indeed more likely to get this disease. However, you will probably also need to be exposed to an environmental trigger to actually manifest the disease.
Narrator: In order to solve this genetic mystery, Criswell is joining a nationwide consortium to study siblings that have rheumatoid arthritis.
Criswell: If we can figure out which genes they share that will give us a direct link to genes, that are likely to cause the disease.
Narrator: And this, Criswell says, can lead to better therapies. For Science Today, I'm Larissa Branin.