In a previous study [19], we showed that hypoxia (Hx) and aging act synergistically to produce hydrocephalus in mice, and three elements decisively contribute to this effect: (i) increased, although disorganized, expression of AQP4 in the brain astrocytes and ependymal cells; (ii) an overload of CSF in the brain ventricles during the hypoxic event; and (iii) a reduction in the CSF evacuation rate and cerebral distensibility. The gene discussed is AQP4; the disease is Hydrocephalus.