Transcriptome analysis studies conducted from patients with hypertension and DM associated with severe COVID-19 cases revealed that ACE2 expression was potentially regulated synergistically by various histone marks such as histone acetyltransferase 1 (HAT1), HDAC2, and lysine demethylase 5B (KDM5B) (264). This evidence concerns the gene KDM5B and COVID-19.