In the brain, abnormal phosphorylation of tau leads to the formation of paired helical filaments, which are the main components of intraneuronal neurofibrillary tangles (NFT) (Grundke-Iqbal et al., 1986) that are characteristic of Alzheimer's disease (AD) and other tauopathies (Lee et al., 2001). Here, MAPT is linked to early-onset autosomal dominant Alzheimer disease.