MAPT and Alzheimer disease: This gene encodes the microtubule-associated protein Tau (MAPT). MAPT transcripts are differentially expressed in the nervous system, depending on stage of neuronal maturation and neuron type. It promotes microtubule assembly and stability, and might be involved in the establishment and maintenance of neuronal polarity. MAPT gene mutations have been associated with several neurodegenerative disorders such as Alzheimer's disease.