The increasing efforts have led to the discovery that in PD and DLB patients, levels of several synaptic proteins are altered in CSF [18–21], and that binding of the PET tracer synaptic vesicle glycoprotein 2 (SV2A) is reduced in the brainstem and cortex [23–25], even though regional results remain inconsistent across studies. The gene discussed is SV2A; the disease is Parkinson disease.