For example, whereas most APP mutations that cause familial AD exhibit robust Aβ plaques and p-Tau tangles in hippocampus, entorhinal cortex, and frontal and temporal lobes, members of a family with an APP V717I mutation exhibited extensive α-synuclein Lewy body pathology in some regions of neocortex and the substantia nigra.27 Interestingly, affected members of the latter family also exhibited robust Aβ and p-Tau pathology in the primary visual cortex, a brain region not usually affected in AD. This evidence concerns the gene MAPT and Alzheimer disease.