Several PET studies with radioligands for 18-kDa translocator protein (TSPO), which is highly expressed in activated microglia in the brain [112], such as 11C-(R)-PK11195 and 11C-DPA713, revealed increased cortical uptake in patients with Parkinson’s disease, especially in the early stage of the disease [113,114,115]. The gene discussed is TSPO; the disease is Parkinson disease.