When transgenic mice expressing wild-type 4R tau were injected with Pick’s disease aggregates, which are predominantly comprised of 3R tau fibrils, fewer induced tau inclusions were observed than in mice injected with either PSP or CBD aggregates, which are predominantly made up of 4R tau fibrils198, suggesting that tau strains preferentially propagate with specific tau isoforms. This evidence concerns the gene MAPT and frontotemporal dementia.