Finally, AQP4 has been shown to have many roles in Alzheimer’s disease, including possibly mediating the clearance of amyloid-β [36,37,38,39], and AQP4 deficiency leads to impaired learning and memory via disruption of both the glutamate transport pathway and K+ ion homeostasis [40,41,42,43]. The gene discussed is AQP4; the disease is early-onset autosomal dominant Alzheimer disease.