Brain degeneration in sporadic Alzheimer’s disease (AD) is recognized earliest in the locus coeruleus (LC), a population of noradrenergic (NA-ergic) neurons, where hyperphosphorylated tau protein is expressed and β-amyloid (Aβ) gradually accumulates, resulting in up to 80% cell death of LC neurons (Vijayashankar and Brody, 1979; Bondareff et al., 1982). The gene discussed is MAPT; the disease is Alzheimer disease.