Imaging showed a loss of hyperintensity in the bilateral substantia nigra, and atrophy in the basal ganglia and frontal lobe on MRI in advanced PD (58), a loss of dorsolateral substantia nigral hyperintensity (the “swallow tail” sign) on susceptibility-weighted imaging (SWI), and reduced dopamine transporter binding in the basal ganglia on dopamine transporter scan imaging SPECT (single-photon emission computed tomography) or PET (position emission tomography) (57, 58). This evidence concerns the gene SLC6A3 and Parkinson disease.