We genotyped the HTT gene CAG repeat number and APOE‐E isoforms in a cohort of patients with neuropathological diagnoses of tauopathies (n=588), including 34 corticobasal degeneration (CBD), 98 progressive supranuclear palsy (PSP) and 456 Alzheimer's disease (AD). The gene discussed is APOE; the disease is Alzheimer disease.