C9orf72 and amyotrophic lateral sclerosis: Interestingly, C9orf72, as the identified risky gene for ALS, showed significant association with ALS (p = 9.41E‐33) and suggestive association with both PM2.5 (p = 2.31E‐2) and NOX (p = 2.61E‐2), indicating that C9orf72 might also exert certain effects from air pollutants to ALS.