MAPT and red-green color blindness: Corticobasal degeneration (CBD) is a rare neurodegenerative disorder characterized byneuronal loss and the predominance of hyperphosphorylated 4-repeat (4R) tau deposition invarious brain regions.1–4 Recently, the 3D structure of tau filaments of CBD wasidentified using cryo-electron microscopic analysis.5 The protofilament structure in CBD is distinct from other4R tauopathies, such as progressive supranuclear palsy (PSP).