With a combination of targeted drugs (3) such as phosphodiesterase-5 inhibitors, endothelin receptor antagonists, prostacyclin analogs, and prostacyclin receptor agonists, patients with pulmonary arterial hypertension (PAH, i.e., WHO group I PH) have shown a significant improvement in activity tolerance and disease prognosis. The gene discussed is PTGIR; the disease is pulmonary arterial hypertension.