C9orf72 and amyotrophic lateral sclerosis: • 64 C9ORF72-positive (31 ALS, 33FTLD)• 79 C9ORF72-negative (36 ALS, 43FTLD)• Neuroimaging available for 41 FTLD patients(14C9ORF72- positive and 27 C9ORF72- negative)