In summary, the findings of this study show that clinical characteristics of amyotrophic lateral sclerosis patients with C9orf72 mutations differ significantly from sporadic amyotrophic lateral sclerosis patients and SOD1 gene carriers, including a higher share of bulbar onset and female patients, faster disease progression rates, higher neurofilament levels in CSF, a larger percentage of neuropsychological deficits and shorter survival. Here, C9orf72 is linked to amyotrophic lateral sclerosis.