To seek further evidence for KDR as a new candidate gene for PAH, we analysed subjects recruited to two cohorts with similar phenotypic characteristics (US PAH Biobank: n = 2572; Columbia University Medical Center: n = 440); four additional individuals harbouring rare high impact KDR variants were identified, with one variant identified in both cohorts. The gene discussed is KDR; the disease is pulmonary arterial hypertension.