Also, mutations in the progranulin gene in patients with FTLD and premorbid bipolar spectrum disorders (19) and in a case of late-onset BD that develop bvFTD (32) as well as lower progranulin plasma levels reported in BD compared to healthy controls (HC) (33, 34) point to common genetic pre-disposing factors. This evidence concerns the gene GRN and behavioral variant of frontotemporal dementia.