TTBK1 and Down syndrome: Many of the tau phosphorylation sites regulated by TTBK1, specifically S422, are found upregulated in a multitude of diseases including: AD, Down’s syndrome, FTDP-17, Progressive Supranuclear Palsy (PSP), Corticobasal Degeneration (CBD), Pick’s Disease, and Chronic traumatic encephalopathy (CTE; Bussiere et al., [47]; Kanaan et al., [48]; Pascual G et al. [49]).