The map of mutations (Fig. 3) suggests that mutations specific for PAH (continuous line) are widely distributed in a few genes: ACVRL1, BMPR2, EIF2AK4, ENG, KCNA5, and SMAD4. Nevertheless, there are many other mutations not yet found in PAH patients that have been found in other diseases. This evidence concerns the gene ENG and pulmonary arterial hypertension.