Interestingly, the multivariate analysis showed that shorter survival time was associated with the presence of C9orf72 expansion in men when stratifying our ALS population by sex, thereby pointing toward the hypothesis that the male sex may drive the effect of the C9orf72 repeat expansion rather than other prognostic factors, such as dementia and the clinical phenotype per se. The gene discussed is C9orf72; the disease is amyotrophic lateral sclerosis.