Hyperphosphorylation of tau and imbalanced expression of 3R-tau and 4R-tau as a result of dysregulation of tau exon 10 splicing are believed to be pivotal to the pathogenesis of tau pathology, but the molecular mechanism leading to the pathologic tau formation in Alzheimer’s disease (AD) brain is not fully understood. The gene discussed is MAPT; the disease is early-onset autosomal dominant Alzheimer disease.