LRRK2 and Parkinson disease: For instance, many of the genes associated with PD, such as α-synuclein, LRRK2, DJ-1, PINK1, and PRKN, are critical for presynaptic function, and knockout mouse models have revealed that the loss of these genes can disrupt synaptic plasticity and neurotransmitter release.1-7 Dysfunctional vesicular dynamics within the synapse have also been implicated in PD pathology.6-9 Although often characterized by dopaminergic neuron loss, many neurotransmitter systems are involved in the pathology of the disease, indicating widespread neurodegeneration.