C9orf72 and frontotemporal dementia: In 2014, Cistaro et al. performed another study, valuating the FDG PET profile of 15 patients with familial ALS carrying the GGGGCC hexanucleotide repeat expansion in the C9ORF72 gene and comparing them with a group of 12 patients with ALS and comorbid frontotemporal dementia (FTD) without the C9ORF72 expansion (ALS-FTD), a group of 30 cognitively normal patients and 40 normal controls.