Consequently to the proposed involvement of HHcy in COVID-19, it was suggested that Hcy may contribute to severe COVID-19 by interfering with G-protein-coupled receptors (GPCRs) (AT1R, B2 and CXCR6), by their upregulation, being an alternative agonist and inducing their heteromerization [38]. This evidence concerns the gene CXCR6 and COVID-19.