Interestingly, Zhao et al.'s research revealed that type II alveolar cells were responsible for the predominant expression of ACE2 in lungs of COVID-19 patients, with relatively low expression of ACE2 in other lung cells such as type I alveolar cells, bronchial epithelial cells, endothelial cells, fibroblasts, and macrophages [15]. The gene discussed is ACE2; the disease is COVID-19.