To treat SSc-related PAH and CTD-PA: - ERA (ambrisentan, bosentan and macitentan) - PDE-5 inhibitors (sildénafil, tadalafil) - Riociguat - Intravenous epoprostenol (severe SSC-PAH with class III and IV dyspnea) - Prostacyclin analogs. The gene discussed is PDE5A; the disease is pulmonary arterial hypertension.