In this context, several studies have inquired the importance of variations in both ACE2 and TMPRSS2 expression and in individual responses to explain the wide range of symptoms and complications in COVID-19 (Lukassen et al. 2020; Asselta et al. 2020; Grifoni et al. 2020; Hou et al. 2020; Pinto et al. 2020). This evidence concerns the gene ACE2 and COVID-19.