MAPT and Alzheimer disease: Specifically, Arrb2 polymorphisms are indicated as risk factors for late onset AD; Taok1 has been shown to actively phosphorylate tau in Alzheimer's brains; folate receptor α, which binds to promotor regions of Fgfr4, showed increased expression in AD fibroblasts; Cacna1g is downregulated in AD brains; and Cacna1h is downregulated in AD human neurons.