[1] Univ Florence, Dip Sci Neurol & Psichiat, I-50134 Florence, Italy
[2] Univ Cambridge, Addenbrookes Hosp, Neurol Unit, Cambridge CB2 2QQ, England
[3] Univ Piermonte Orientale A Avogadro, Dept Med Sci, Chair Human Genet, Novara, Italy
[4] Inst Publ Hlth, MRC, Biostat Unit, Cambridge CB2 2SR, England
[5] Univ La Sapienza, Dept Neurol Sci, I-00185 Rome, Italy
[6] Univ Catanzaro, Dept Med Sci, Catanzaro, Italy
[7] CNR, Inst Expt Med & Biotechnol, I-00185 Rome, Italy
[8] Univ Bari, Dept Neurol & Psychiat Sci, I-70121 Bari, Italy
[9] Univ Florence, Dept Neurol & Psychait Sci, I-50121 Florence, Italy