IFN-γ signaling thus can have significant effects on immune response,41 neurotransmitter synthesis29 and circulation42 in patients with acute COVID-19: Impairment of Trp and Phe metabolism29,43 and decreased NO availability44 have been demonstrated in COVID-19 infected patients and might in fact impair their physical and mental performance. The gene discussed is IFNG; the disease is COVID-19.