Therefore, in the whole blood samples of hospitalized COVID-19 patients, we examined the gene expression of MAOA and MAOB, the products of which perform the oxidative deamination of biogenic amines, including dopamine, norepinephrine, and serotonin, DBH, which converts dopamine to norepinephrine, and of the catecholamine transporter-gene VMAT2. Here, SLC18A2 is linked to COVID-19.