Presymptomatic geographical distribution of ALS patients suggests the involvement of environmental factors in the disease pathogenesis.

"Declarations Conflicts of interestRosario Vasta, Stefano Callegaro, Silvia Sgambetterra, Sara Cabras, Francesca Di Pede, Filippo De Mattei, Enrico Matteoni, Maurizio Grassano, Alessandro Bombaci, Giovanni De Marco, Giuseppe Fuda, Giulia Marchese, Francesca Palumbo, Antonio Canosa, Umberto Manera, Letizia Mazzini, Fabiola De Marchi: no disclosures. Andrea Calvo has received research support from the Italian Ministry of Health (Ricerca Finalizzata). Cristina Moglia has received research support from the Italian Ministry of Health (Ricerca Finalizzata). Adriano Chiò serves on the editorial advisory board of Amyotrophic Lateral Sclerosis and Neurological Sciences and has received research support from the Italian Ministry of Health (Ricerca Finalizzata), Regione Piemonte (Ricerca Finalizzata), University of Turin and the European Commission (Health Seventh Framework Programme) and serves on scientific advisory boards for Biogen Idec, Cytokinetics, Italfarmaco. Ethical standardThe study was approved by the Ethical Committee of the Turin ALS Center (Comitato Etico Azienda Ospedaliero-Universitaria Città della Salute e della Scienza, Torino). Informed consentPatients provided written informed consent before enrollment. The databases were anonymized according to the Italian law for the protection of privacy. Conflicts of interest Rosario Vasta, Stefano Callegaro, Silvia Sgambetterra, Sara Cabras, Francesca Di Pede, Filippo De Mattei, Enrico Matteoni, Maurizio Grassano, Alessandro Bombaci, Giovanni De Marco, Giuseppe Fuda, Giulia Marchese, Francesca Palumbo, Antonio Canosa, Umberto Manera, Letizia Mazzini, Fabiola De Marchi: no disclosures. Andrea Calvo has received research support from the Italian Ministry of Health (Ricerca Finalizzata). Cristina Moglia has received research support from the Italian Ministry of Health (Ricerca Finalizzata). Adriano Chiò serves on the editorial advisory board of Amyotrophic Lateral Sclerosis and Neurological Sciences and has received research support from the Italian Ministry of Health (Ricerca Finalizzata), Regione Piemonte (Ricerca Finalizzata), University of Turin and the European Commission (Health Seventh Framework Programme) and serves on scientific advisory boards for Biogen Idec, Cytokinetics, Italfarmaco."

"Funding Open access funding provided by Università degli Studi di Torino within the CRUI-CARE Agreement. This work was in part supported by the Italian Ministry of Health (Ministero della Salute, Ricerca Sanitaria Finalizzata, Grant RF-2016-02362405), the European Commission’s Health Seventh Framework Programme (FP7/2007-2013 under Grant agreement 259867), the Italian Ministry of Education, University and Research (Progetti di Ricerca di Rilevante Interesse Nazionale, PRIN, Grant 2017SNW5MB), the EU Joint Programme—Neurodegenerative Disease Research (ALS-Care, Strength and Brain-Mend projects), granted by the Italian Ministry of Education, University and Research, the European Union’s Horizon 2020 research and innovation programme (Brainteaser Project, Grant GA101017598), and the Susa and Val Susa Rotary Club. This study was performed under the Department of Excellence grant of the Italian Ministry of Education, University and Research to the’Rita Levi Montalcini’ Department of Neuroscience, University of Torino, Italy. The study was supported by the AGING Project for Department of Excellence at the Department of Translational Medicine (DIMET), Università del Piemonte Orientale, Novara, Italy."