C9orf72 and amyotrophic lateral sclerosis: Based on allocated cluster membership, the demographic, clinical and genetic profiles of the two clusters were evaluated; Cluster 1: n = 76 age: 61.9 ± 11.9, male: 54 (71.1%), right handed: 73 (96.1%), education 13.5 ± 3.2, spinal onset: 67 (88.2%), ALSFRS-r: 37.9 ± 5.4, impaired on ECAS: 20 [26.3% of subjects in the cluster, 29.8% of subjects with ECAS available in the cluster (n = 67)], ALS-FTD: 13 (17.1%), C9orf72 hexanucleotide carriers: 16 (21.1% of cluster).