Mutations and variants in the MAPT gene, encoding the microtubule-associated protein tau, as well as deposition of misfolded tau as neuropathological correlate have been linked to several neurodegenerative diseases, such as familial frontotemporal dementia with parkinsonism linked to chromosome 17 [124], progressive supranuclear palsy [125], chronic traumatic encephalopathy [126], amyotrophic lateral sclerosis (ALS) [127], Alzheimer’s disease (AD) and PD [121–123, 128, 129]. The gene discussed is MAPT; the disease is early-onset autosomal dominant Alzheimer disease.