TTYH1 and Alzheimer disease: Microarrays also demonstrate brain location-dependent TTYH1 expression patterns in Alzheimer’s disease patients as the hippocampus and entorhinal cortex samples showed TTYH1 downregulation while superior frontal gyrus and middle temporal gyrus samples revealed TTYH1 (and TTYH2) upregulation (Xu et al., 2006; Liang et al., 2007; Papatheodorou et al., 2020).