C9orf72 and amyotrophic lateral sclerosis: Cluster 2: n = 138, age: 60.5 ± 11.9, male: 86 (62.3%), right handed: 129 (93.5%), education 14.1 ± 3.3, spinal onset: 119 (86.2%), ALSFRS-r: 38.8 ± 6.2, impaired on ECAS: 21 (15.2% of subjects in the cluster, 17.9% of subjects with ECAS available in the cluster (n = 117)), ALS-FTD: 15 (10.9%), C9orf72 hexanucleotide carriers: 6 (4.3% of cluster).