TMPRSS2 and Alzheimer disease: Furthermore, utilizing postmortem brain specimens from three groups of non-infected elder subjects (controls without AD, subjects with late-onset AD, and subjects with DS and AD (DS-AD)), we analyzed the expression of SARS-CoV-2 entry proteins (ACE2 and TMPRSS2) and proteins that reflect interferon system activity (STAT1 and STAT2) in the human entorhinal cortex region.