GRN and Atrophy: Group and single case studies suggest that atrophy in association with GRN mutations is asymmetrical and widespread within the affected hemisphere, involving the frontal, temporal and parietal lobes even in the presymptomatic phase, whilst atrophy in association with MAPT mutations is more symmetrical and relatively restricted within the frontal and temporal lobes (Whitwell et al., 2007; Beck et al., 2008; Rohrer et al., 2008; Whitwell et al., 2009a).