BMPR2 and pulmonary arterial hypertension: Herein, we conducted an expanded clinical 18FLT‐PET study (a) to include a larger group of PAH patients and an appropriate control group of healthy subjects, aiming to validate the clinical application of 18FLT‐PET as a biomarker for PAH severity and (b) to include a group of unaffected BMPR2 mutation carriers, aiming to assess if 18FLT‐PET can discriminate carriers that may be at risk of developing the subclinical pulmonary vascular remodelling.