MAPT and argyrophilic grain disease: Globular glial tauopathy (GGT) and argyrophilic grain disease (AGD) also both present with 4R tau aggregates, in neurons and oligodendroglia in GGT, and in the form of argyrophilic grains and astroglial, oligodendroglial and neuronal deposits, in AGD (reviewed in [17]).