1 Department of Medical Genetics, University of Medical Sciences, Poznań, PolandLaboratory of Neurogenetics, Flanders Interuniversity Institute for Biotechnology (VIB), Born-Bunge Foundation (BBS), University of Antwerpen (UIA), Department of Biochemistry, Antwerpen, BelgiumNeuromuscular Unit, Medical Research Centre, Polish Academy of Sciences, Warsaw, PolandDepartment of Neurology, Medical University, Warsaw, Poland.