[1] Univ Cattolica Sacro Cuore, Dept Paediat Neurol, I-00168 Rome, Italy
[2] Univ Messina, Dept Neurosci Psychiat & Anaesthesiol, I-98100 Messina, Italy
[3] Bambino Gesu Pediat Hosp, Mol Med Unit, Dept Lab Med, Rome, Italy
[4] Unione Italiana Lotta Distrofia Muscolare, UILDM, Rome, Italy
[5] Bambino Gesu Pediat Hosp, Epidemiol Unit, Rome, Italy
[6] Univ Pisa, Unit Child Neurol & Psychiat, I-56100 Pisa, Italy
[7] IRCCS, San Giovanni Rotondo, Italy
[8] UCL, Inst Child Hlth, Dubowitz Neuromuscular Ctr, London, England
[9] Nigrisoli Hosp, Bologna, Italy