1 Philipps-University Marburg, University Clinic Marburg, Internal Medicine-Cardiology and Center for Undiagnosed Diseases, Marburg, Germany.
2 Medizinisches Labor Bremen, Bremen, Germany.
3 Philipps-University Marburg, University Clinic Marburg, Internal Medicine-Cardiology and Center for Undiagnosed Diseases, Marburg, Germany. Electronic address: juergen.schaefer@uni-marburg.de.