In Alzheimer’s disease (AD) research, the CSF biomarkers amyloid β (a marker of amyloid plaque pathology), and the tau protein (a marker of axonal destabilization) with its phosphorylated forms (markers of increased tau phosphorylation, which are related to neurofibrillary tangle formation) have played central roles for our current understanding of the pathological mechanisms involved in the disease [2]. Here, MAPT is linked to early-onset autosomal dominant Alzheimer disease.