MAPT and Alzheimer disease: Quantification of SCRN1 intensity inside and outside PHF1-positive lesions confirmed our findings (Fig. 4d, e), showing that SCRN1 accumulation is a feature unique to NFTs in AD where both 3R-Tau and 4R-Tau isoforms are present and that this occurs across multiple brain regions (hippocampus, cortex and basal ganglia examined in this study).