A study by Pinto et al. [100] analyzed the expression of ACE-2 in more than 700 lung transcriptome samples of patients with diseases including hypertension, diabetes, lung diseases (COPD or pulmonary arterial hypertension) as well as cancer; as compared to healthy individuals, ACE-2 was upregulated in patients with comorbidities [100,101], indicating patients presenting with these disease are at a higher risk of developing COVID-19. Here, ACE2 is linked to pulmonary arterial hypertension.