Moreover, decreased DLco/alveolar volume ratio and an increased NT-proBNP are predictors of PAH in SSc [161], Treatment guidelines of the Task Force for the Diagnosis of Treatment of PAH of the European Society of Cardiology and European Respiratory Society indicate that plasma levels of BNP and NT-proBNP are key parameters for assessing the severity, stability, and prognosis of PAH [162]. This evidence concerns the gene NPPB and pulmonary arterial hypertension.