Researchers at Karolinska Institutet have found links between certain blood groups and a total of 49 diseases, including a new finding that having blood group B seems to be a protective factor against kidney stones. The study, which includes data on more than five million people and over 1,000 diseases, confirms previously identified connections between certain blood groups and increased risk of blood clots, bleeding conditions or pregnancy-induced hypertension. The result is published in eLife.