For example, a small study by Ossenkoppele et al. utilizing the 18F-AV-1451 tau PET ligand in 20 individuals diagnosed with MCI or AD found increased uptake of the PET ligand in bilateral medial temporal and right temporoparietal cortex of APOE4+ patients, as compared to APOE4− patients [108]. The gene discussed is MAPT; the disease is Alzheimer disease.