Interestingly, only the endothelial HIF-1α knockout model accrues severe right ventricular dysfunction (emblematic of PAH) in mouse models, whereas HIF-2α knockout does not; furthermore, patients with IPAH had higher HIF-2α levels than HIF-1α (Dai et al., 2016). The gene discussed is EPAS1; the disease is pulmonary arterial hypertension.