1. Department of Neurology, University of Ulm, Ulm, Germany
2. Institute of Physiological Chemistry, University of Ulm, Ulm, Germany
3. Department of Neurology, Dresden University of Technology, Dresden, Germany
4. Institute of Anatomy and Cell Biology, University of Ulm, Ulm, Germany
5. Center for Regenerative Therapies Dresden, Dresden University of Technology, Dresden, Germany
6. Institute of Human Genetics, Ernst-Moritz-Arndt University of Greifswald, Greifswald, Germany
7. Department of Neurology, University of Leipzig, Leipzig, Germany, and Division of Biology, California Institute of Technology, Pasadena, California, USA