IFNB1 and pulmonary arterial hypertension: In the few reported cases of IFN-β-associated PAH, only one had a definite risk factor of PAH (atrial septal defect) which resolved after surgical repair.3 In other cases, PAH was severe and making combination treatment of was necessary, leading to death in 2 cases.3 In all previous cases, PAH was developed after more than 3 years of IFN-β injections.