[1] Catholic Univ, Dept Paediat Neurol, Rome, Italy
[2] UCL, Inst Child Hlth, Dubowitz Neuromuscular Ctr, London, England
[3] C Besta Neurol Inst IRCCS, Dev Neurol Unit, Milan, Italy
[4] IRCSS Stella Mans, Dept Dev Neurosci, Pisa, Italy
[5] Bambino Gesu Pediat Hosp, Dept Neurosci, Unit Neuromuscular & Neurodegenerat Dis, Rome, Italy