Getty Images In a new study, Mayo Clinic researchers and collaborators have described — for the first time — the prevalence of autoimmune diseases in the U.S. Their research, published in the Journal of Clinical Investigation, reports that about 15 million people are estimated to have one or more of 105 autoimmune diseases. The study also found that autoimmune diseases occur most often in women and identified the top autoimmune diseases by prevalence, sex and…