AQP4 and pathologic nystagmus: We also deliberate on how our case was different from prior KIDINS220-related pathologies including spastic paraplegia, intellectual disability, nystagmus, and obesity (SINO) syndrome, and the observation of KIDINS220 and aquaporin-4 (AQP4) downregulation in the ventricular ependymal lining of idiopathic normal pressure hydrocephalus (iNPH) patients.