ACE is a component of the renin-angiotensin system (RAS) axis that is involved in the homeostasis of cardiovascular function (48) and downregulated by ACE2; serum ACE can be frequently upregulated in patients with sarcoidosis and significantly higher when compared with healthy controls so that it has been considered as a possible serum biomarker for the diagnosis of sarcoidosis or the monitoring of disease activity (49). The gene discussed is REN; the disease is sarcoidosis.