AQP4 and Parkinson disease: This resulted in an increased buildup of α‐synuclein, activation of glial cells, heightened inflammation, loss of dopaminergic neurons, and motor deficits, pointing to the involvement of compromised lymphatic clearance in PD pathology.27,34 Zhang et al5 demonstrated that deletion of the AQP4 gene resulted in reduced clearance of injected α‐synuclein in mice.