Our exploratory C9orf72 positive versus negative analyses were largely commensurate with previous studies in FTD C9orf72 expansion carriers, supporting distinct patterns with C9orf72 FTD expansion carriers showing atrophy involving the frontotemporal, insular and parietal, occipital, thalamic and cerebellar regions, while individual cases can show more posterior atrophy.61 Here, C9orf72 is linked to frontotemporal dementia.