According to the recently proposed diagnostic criteria of AD, the preclinical AD stage is characterized by the absence of clinical signs and symptoms of AD and the presence of at least one biomarker of Alzheimer’s pathology (decreased level of Aβ42, increased level of tau p-tau in cerebrospinal fluid or abnormal deposition of Aβ and tau in the brain that can be revealed by positron emission tomography) (Dubois et al., 2014). The gene discussed is MAPT; the disease is Alzheimer disease.