By developing the rTgTauEC mouse model of early AD that overexpresses human mutant P301L tau selectively in the EC, we and other groups have demonstrated that aggregated tau accumulates in synaptically connected downstream areas such as dentate gyrus, suggesting that NFT propagation occurs by cross-synaptic spread of pathologically misfolded tau proteins9, 10, 11, 12. This evidence concerns the gene MAPT and Alzheimer disease.