For this purpose, we analysed clinical parameters including age of onset, body mass index (BMI), diagnostic delay, family history, gender distribution, site of onset, neuropsychological status, progression rate and survival in n = 248 patients with amyotrophic lateral sclerosis carrying mutations in the C9orf72 gene and compared them to n = 84 amyotrophic lateral sclerosis patients with SOD1 mutations and n = 2178 sporadic amyotrophic lateral sclerosis patients without any known amyotrophic lateral sclerosis-related genetic mutations. Here, C9orf72 is linked to amyotrophic lateral sclerosis.