This view was formally articulated in the recent publication of novel Alzheimer's Association diagnostic and staging criteria for AD, which suggest that the disease can be diagnosed when a so‐called ‘Core 1’ biomarker of Aβ proteinopathy or phosphorylated and secreted tau is abnormal, resulting in a purely biological definition of the disease (Jack et al., 2024). The gene discussed is MAPT; the disease is Alzheimer disease.