Currently, the diagnosis of Alzheimer's disease is made based on the clinical presentation of the patients and the laboratory diagnosis of three biomarkers in the cerebrospinal fluid (CSF): amyloid-beta 42, total tau, and phospho-tau, out of which beta-amyloid 42 is the most sensitive biomarker [11]. The gene discussed is MAPT; the disease is early-onset autosomal dominant Alzheimer disease.