1. Department of Biomedical, Surgical and Dental Sciences, University of Milan, Italy,
2. Environmental, Genetic, and Nutritional Epidemiology Research Center-CREAGEN, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy,
3. Department of Neurology, ALS Center, Azienda Ospedaliero Universitaria Maggiore della Carità, Novara, Italy,
4. ICS Maugeri, Scientific Institute of Veruno (NO), Veruno, Italy,
5. Rita Levi Montalcini Department of Neuroscience, ALS Center, University of Turin, Turin, Italy, and
6. Hygiene and Public Health Service, ASL Novara, Novara, Italy