In this regards, passive immunization targeting the N-terminally truncated forms of tau is being currently pursued in phase I clinical trials [113] based on the findings that multiple fragments containing NH2/mid-region of human protein -but not its C-terminally cleaved and full length isoform(s)- are mostly detected in CSF from AD patients [9, 10, 11, 12] and in conditioned media from AD patient-derived induced pluripotent stem cells (iPSC) cortical neurons [13, 14]. This evidence concerns the gene MAPT and Alzheimer disease.