Besides ACE2 and Ang II, RAS can also be regulated by insertion/deletion (I/D) polymorphism of the ACE gene increasing the risk of severe forms of COVID-19 (Marshall et al., 2002; Harrap et al., 2003; Sayed-Tabatabaei et al., 2006; Gupta et al., 2009; Yamamoto et al., 2021). Here, ACE2 is linked to COVID-19.