Several genes in this group (CTSG, encoding the neutrophil serin protease Cathepsin G; DEAFA4, defensin alpha 4; LCN2, lipocalin 2; OLFM4, BPI and CD24) (Fig. 3c), are known to be overexpressed in patients with severe viral infections, including COVID-197,14. Here, LCN2 is linked to viral infectious disease.