[1] Ruhr Univ Bochum, Staedt Kliniken Neuss, Ctr Neuropediat, Neuromuscular Lab, D-4630 Bochum, Germany
[2] Jefferson Med Coll, Jefferson Inst Mol Med, Philadelphia, PA USA
[3] Univ Wurzburg, Wurzburg, Germany
[4] Univ Freiburg, Freiburg, Germany
[5] Univ Bonn, D-5300 Bonn, Germany