As the reference therapy, we applied the combination of the inhibitor of phosphodiesterase 5 (PDE-5) tadalafil (TAD) together with the endothelin 1 (ET-1) receptor antagonist ambrisentan (AMB), since the early combination therapy is currently the gold standard for most patients with PAH [5]. This evidence concerns the gene PDE5A and pulmonary arterial hypertension.