In addition to the epithelial airway cells, the co-expression of ACE2 and TMPRSS2 has also been identified in type II pneumocytes, bronchial transient secretory cells, absorptive enterocytes in the small intestine, and nasal goblet secretory cells, all of which are typical sites of COVID-19 symptoms [16]. The gene discussed is TMPRSS2; the disease is COVID-19.