PPP2R5D and Parkinson disease: Other groups have reported increased neurites and dendritic branching in alpha-synuclein models of Parkinson’s Disease (PD).31,32 A hallmark of PD pathology is a reduction in dopamine release into the striatum following a loss of neurons in the substantia nigra pars compacta.33 Our findings suggest EOPD phenotypes associated with PPP2R5D dysregulation do not result from neuronal loss since a higher number of E198K midbrain neurons was observed following a 9-day maturation.