In summary, we present a series of patients with idiopathic and associated PAH with a high percentage of mutations in BMPR2 and lower in ACVRL1 and KCNA5 genes, some of them not previously described, showing some clinical and hemodynamic differences which suggest that the presence of these mutations may be associated with more severe disease. This evidence concerns the gene KCNA5 and pulmonary arterial hypertension.