1. University Hospital of Tübingen, Tübingen, Germany (T.E., D.L.)
2. Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich, Tübingen, Germany (J.M.)
3. Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich and University Hospital of Tübingen, Tübingen, Germany and Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts (N.S.)