PRKN and Parkinson disease: As there is dopaminergic neuron loss in PD and DLB, and prior work demonstrated significant dopaminergic neuron loss in the protocerebral posterior lateral 1 (PPL1) cluster of dopaminergic neurons (outlined in Fig 3D) in several Drosophila models of PD, including parkin mutants [24] and α-synuclein transgenic flies [25], we tested whether GBA1ΔTT homozygotes also exhibit dopaminergic neuron loss.