In COVID-19, it has been postulated that modifications of the dopamine and serotonin synthetic pathways contribute to COVID-19 pathophysiology, as gene co-expression, co-regulation, and function are linked between Angiotensin I Converting Enzyme 2 (ACE2) and Dopa Decarboxylase (DDC) [10, 11]. The gene discussed is DDC; the disease is COVID-19.