ACE2 and Parkinson disease: The analysis of the pathways involved in the downregulation of ACE2 following SARS-CoV-2 infection and its effect on PD progression. The molecules and chemicals associated with COVID-19 and PD were subjected to Ingenuity Pathway Analysis (IPA) “Grow”; 81 overlapping molecules between COVID-19 and PD were further subjected to IPA’s “Core Analysis” tool to identify the upstream regulators and signaling pathways.