Estanga and colleagues [48], for instance, conducted a neurobiological study on healthy, middle-aged individuals, analyzing Alzheimer’s disease (AD) biomarkers in cerebrospinal fluid (e.g., amyloid beta (Aβ) 1‒42, total-tau, and phosphorylated-tau, as well as ratios of total-tau/Aβ1‒42 and phosporylated-tau/Aβ1‒42). The gene discussed is MAPT; the disease is Alzheimer disease.