Current PAH treatments, based on drugs mimicking or inhibiting these endogenous vasoactive factors, are categorized into three classes: (1) prostacyclin and IP receptor agonists, (2) phosphodiesterase type 5 (PDE5) inhibitors and soluble guanylate cyclase (sGC) stimulators and (3) ET-1 receptor antagonists [8,9]. This evidence concerns the gene PDE5A and pulmonary arterial hypertension.