KEGG results showed that marker genes were mainly enriched in pathways activated to function in B cells, including ribosome, coronavirus disease-COVID-19, intestinal immune network for lgA production, B cell receptor signalling pathway, hematopoietic cell lineage, Leishmaniasis, Antigen processing and presentation, Toxoplasmosis, Allograft rejection, and Type I diabetes mellitus (Figure 4B). Here, GLS2 is linked to COVID-19.