Increased, ectopic expression of human ACE2 in transgenic mice has been shown to correlate with an increase in SARS-CoV replication, coupled with an increase in expression of the genes furthering viral reproduction. It is hypothesized that ACE2 expression may aid viral entry and/or replication, and pose as a risk factor for COVID-19 infection/severity.

• ACE2 and viral entry: low ACE2 Expression as sufficient for SARS-CoV-2 Infection
• ACE2 and comorbidities: increased ACE2 expression in cancerous tissues