ARTICLE EXTRAS
Why anyone develops an autoimmune disease is one of the central puzzles in immunology. Scientists recognize that genetic and environmental factors play a role, "but how these two interact to cause autoimmunity is still a mystery," says Yaron Tomer, a professor of medicine at the University of Cincinnati.
The mystery unfolds with this observation: Even in autoimmune diseases considered to have a strong genetic component, the concordance rate in identical twins is often relatively low. For example, the concordance for monozygotic twins with multiple sclerosis is around 30%, for rheumatoid arthritis (RA) between 12% and 30%, and for systemic lupus erythematosus (SLE) between 24% and 69%. Such numbers leave plenty of room for environmental factors that can trigger these diseases.
Unfortunately, according to Tomer, it isn't easy to sort out the genetics from the environment. "Each one is complex in its own right," he says. In the 1980s, ...
