1. Medical Center for Human Genetics, Marburg University, D-3550 Marburg, Germany.
2. Center for Molecular Neurobiology (ZMNH), Hamburg University, D-2000 Hamburg 20, Germany.
3. Clinical Neurology, Würzburg University, D-8700 Würzburg, Germany.
4. Institute for Human Genetics, Göttingen University, D-3400 Göttingen, Germany.
5. Clinical Neurology, Technical University, D-8000 Munich, Germany.