We first analyzed the levels of tau and phosphorylated tau in these tissue samples by Western blots developed with antibodies 77G7 (pan-tau) and PHF-1 (phospho-tau at Ser396/404) (Fig. 3a) and found hyperphosphorylation of tau at Ser396/404, which also displayed SDS- and β-ME resistant HMW-species, the common features of AD and related tauopathies, in AD2-5 and PiD3, but not in Con1-5, AD1, CBD1-3, PiD1,2, and PSP1,2 brains (Fig. 3a), suggesting that the pathology in these cases is not evenly distributed throughout the frontal cortex in tauopathies. This evidence concerns the gene PHF1 and Alzheimer disease.