Endothelin-1, a potent vasoconstrictor and HIF target, is significantly increased in Chuvash mice and could be a downstream effector molecule in the pathogenesis of pulmonary hypertension (Bushuev et al., 2006; Hickey et al., 2010; Thorin and Clozel, 2010; Shao et al., 2011). Here, EDN1 is linked to pulmonary arterial hypertension.