Tau seeding and spreading is produced following the intracerebral inoculation of synthetic tau fibrils [6,7] or inoculation of fibrillar-enriched fractions from human and mouse brain homogenates of tauopathies, including Alzheimer’s disease (AD), tangle-only dementia progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), and argyrophilic grain disease (AGD), as well as tau transgenic mice in various transgenic mouse models [8,9,10,11,12]. The gene discussed is MAPT; the disease is early-onset autosomal dominant Alzheimer disease.