A recent prospective case-control study assessed the causality of lifestyle factors in the pre-symptomatic phase of ALS, in participants with the C9orf72 mutation.28 They compared C9-positive ALS patients (n = 143), C9-negative ALS patients (n = 1322) and healthy controls (n = 1322). The gene discussed is C9orf72; the disease is amyotrophic lateral sclerosis.