In this study which established 4R Tau RT-QuIC, positive responses were obtained from all PSP and CBD post-mortem CSF samples and no controls but antemortem CSF samples had weaker seeding activity (Saijo et al., 2020). The other study detecting 4R tau seeds used brain homogenate samples only (Tennant et al., 2020). The gene discussed is MAPT; the disease is red-green color blindness.