Such is the case of the study of Harriott and Ryan [89], who observed that proteins such as TNFβ, IL-6, IL-8, IL-12, CXCL10, syndecan-1 (SYND1), and EN-RAGE were positively regulated in cases of severe COVID-19, after comparing the expression of proteins in the blood plasma of patients with different severities (mild, moderate, or severe). This evidence concerns the gene SDC1 and COVID-19.