Since only a few individuals were studied, it remainsto be elucidatedif the increased expression of the ACE2 protein in endothelial cellsof certain COVID-19 patients is due to inter-individual variationcaused by direct effects of the SARS-CoV-2 virus, which are triggeredby mechanisms related to brain injury or other previous underlyingdiseases such as Alzheimer’s disease. This evidence concerns the gene ACE2 and early-onset autosomal dominant Alzheimer disease.