First, it is established that infection with the SARS-CoV-2 virus involves interactions between its spike (S) protein and angiotensin-converting enzyme II (ACE2) on target cells, with this interaction requiring cleavage of the S protein by the cell surface protease called transmembrane protease serine 2 (TMPRSS2) [28,29]. The gene discussed is TMPRSS2; the disease is infection.