Introduction: "Pulmonary arterial hypertension (PAH) is a rare vascular disorder, characterized by narrowing of the pulmonary arteries due to vasoconstriction and vascular remodeling [1–3]. The national registry reports a PAH incidence of 5.2 cases per million per year and a prevalence of 30.8 cases per million in Poland [4, 5]. While its etiology remains partly unclear, genetic factors have been implicated in certain patient groups [6–8]. However, the molecular background of this population has not been systematically studied. Therefore, we aimed to comprehensively characterize the genetic landscape of PAH in Polish patients." (...)