TMPRSS2 and COVID-19: So far, few studies have shown the roles of angiotensin-converting enzyme 1 (ACE1), ACE2, and transmembrane protease serine 2 (TMPRSS2) gene variants in the COVID-19 severity (Gorbalenya et al., 2020; Hou et al., 2020; de Araújo et al., 2022; Gintoni et al., 2022).