Additionally, in severe COVID-19 patients, it has been observed a differential methylation in the promoters of the Angiotensin Converting Enzyme 2 (ACE2) receptor gene, which the SARS-CoV-2 virus exploits to enter host cells, and of the Transmembrane Serine Protease 2 (TMPRSS2), that processes it [32, 33]. This evidence concerns the gene TMPRSS2 and COVID-19.