Tau isolated from mesial frontal cortex and subcortical at postmortem demonstrates a significantly greater propensity for fibril formation in a thioflavin S assay, partitions into the sarkosyl-insoluble fraction as all 6 isoforms (distinguishing it from Alzheimer's disease tau, 3R or 4R tau disorders), and is pathologically phosphorylated at Thr175 (pThr175tau) (112). The gene discussed is MAPT; the disease is Alzheimer disease.