In PAH, oestrogens promote right ventricle adaptation in women,23 which might lead to a less severe phenotype compared to men.24 Further, chromosomal differences also play a role, for instance, the Y-chromosome is thought to have vascular protective gene expression profiles in PAH.25 In this review, we further discuss if sex determinants, i.e. sex hormones and -chromosomal effects, are a driver of PAH development by altering transforming growth factor-β (TGFβ) signalling. This evidence concerns the gene TGFB1 and pulmonary arterial hypertension.