A security system wired within every cell to detect the presence of rogue viral DNA can sometimes go awry, triggering an autoimmune response to single-stranded bits of the cell's own DNA, according to a report in the August 22nd issue of the journal Cell, a Cell Press publication. The source of that single-stranded DNA is so-called endogenous retroelements—genetic elements accounting for a substantial portion of the genome that can move to new locations using a "copy and paste" mechanism, according to the researchers.
The new findings help to explain the cause of a rare autoimmune disorder known as Aicardi-Goutieres Syndrome in which infants appear to suffer from an acute viral infection, despite the fact that no virus had ever been found.
"We and others had demonstrated the existence of a DNA detection pathway within cells, but we are still early in our understanding," said Daniel Stetson of the Howard Hughes Medical Institute and the University of Washington, Seattle. "Our findings offer an important piece of evidence that this pathway is not only very relevant, but it can be the cause of severe autoimmune disease."
http://www.sciencedaily.com/releases/2008/08/080821163850.htm