MAPT and Alzheimer disease: From a molecular perspective, “tauopathies” are classified into three groups based on the tau isoforms found in the aggregates: 4R tauopathies (e.g., progressive supranuclear palsy, corticobasal degeneration and argyrophilic grain disease), 3R tauopathies (e.g., Parkinson’s disease) and mixed 3R + 4R tauopathies (e.g., AD) [80].