1. From the Department of Nephrology, Heinrich-Heine-University (I.Q., L.S., J.S., L.C.R.), Düsseldorf, Germany; the Department of Internal Medicine I (O.V.), Ruhr University, Bochum, Germany; Marienhospital (G.D.), Herne, Germany; and the Department of Human Genetics (G.D.), Ruhr University, Bochum, Germany.