SYNJ1 and Parkinson disease: PIP5K1γ is the major isoform expressed in neuronal tissue and highly concentrated at synapses.38 Linking PM PI(4,5)P2 to PD are mutations in the PI(4,5)P2-metabolizing enzyme synaptojanin1 (SYNJ1) that cause inherited forms of PD (PARK20)39 and SYJN1 haploinsufficiency, which drives dopaminergic neuron vulnerability.40 Despite these correlative associations, there remains a paucity of information on the molecular underpinnings that link α-Syn aggregation, PI(4,5)P2 dysregulation, and neuronal cell death.