1. INSERM, University of Limoges, CHU Limoges, IRD, U1094 Tropical Neuroepidemiology, Institute of Epidemiology and Tropical Neurology, GEIST,Limoges, France
2. Department of Neurology, ALS expert centre, CHU Limoges,Limoges, France
3. Unit of Biostatistics, IRCCS ‘‘Casa Sollievo della Sofferenza’’, San Giovanni Rotondo, Italy
4. Unit of Neurodegenerative Diseases, Department of Clinical Research in Neurology, University of Bari ‘‘Aldo Moro’’, at ‘‘Pia Fondazione Cardinale G. Panico’’, Lecce, Italy
5. Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
6. Department of Basic Medical Sciences, Neuroscience and Sense Organs, University of Bari ‘‘Aldo Moro’’, Bari, Italy
7. Centre d’Epidémiologie, de Biostatistique et de Méthodologie de la Recherche, CHU Limoges, Limoges, France