The authors wish to thank Dr. Cornelia Kornblum for her helpful comments and Jennifer Bradshaw for the critical reading of the manuscript. D.F. was supported by the Deutsche Forschungsgemeinschaft (DFG) and is a member of the German Network on Muscular Dystrophies (MD-NET) funded by the German Ministry of Education and Research (BMBF, Bonn, Germany). Open Access This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.