Women are far more likely than men to get autoimmune diseases, when an out-of-whack immune system attacks their own bodies — and new research may finally explain why. It’s all about how the body handles females’ extra X chromosome, Stanford University researchers reported Thursday — a finding that could lead to better ways to detect a long list of diseases that are hard to diagnose and treat. “This transforms the way we think about this whole process of autoimmunity, especially the male-female bias,” said University of Pennsylvania immunologist E. John Wherry, who wasn’t involved in the study.