Our results showed that the gene expression of DDC (L-Dopa decarboxylase) [8] and of the recently reported interferon-inducible truncated dACE2 isoform [4, 5] was significantly higher in nasopharyngeal swab samples from COVID-19 patients with no or mild symptoms, as compared to non-infected individuals, while it was negatively correlated with SARS-CoV-2 RNA levels in patients and was negatively affected by the virus in cell culture-infected epithelial cells. Here, DDC is linked to COVID-19.