Li et al. (76) found that circulating endothelial cells (CECs) and ET-1 levels were significantly elevated in patients with PAH-CHD than healthy controls, as well as positively correlated with the indicators for assessing the severity of PAH: mPAP, arterial partial pressure of oxygen, and arterial oxygen saturation. The gene discussed is EDN1; the disease is pulmonary arterial hypertension.