Recent reports of C9ORF72 mutations suggest these are a common cause of FTD and motor neuron disease, representing approximately one-third of all cases due to genetic mutations [5,6], of comparable frequency to mutations in progranulin (GRN) and micro-tubule protein tau (MAPT) as a cause of autosomal dominant FTD [6]. Here, C9orf72 is linked to frontotemporal dementia.