PD imaging studies, as summarized elegantly by Cheng et al. (2010) for studies on dopamine transporter binding using positron emission tomography (PET) and single photon emission computed tomography (SPECT) technology, show a loss of striatal binding by 59% (mean of three studies by Tissingh et al. 1998; Lee et al. 2000; and Schwartz et al. 2004). The gene discussed is SLC6A3; the disease is Parkinson disease.