A co-occurrence of PAH and FHM supports the hypothesis of a potential common pathophysiological link; several studies have reported the presence and activity of the α2-subunit of the Na+/K+-ATPase in pulmonary vascular smooth muscle cells [191,192], and the decrease in expression and/or activity of different types of K+ channels in PASMCs of IPAH patients [193,194], and Montani et al. [190] suggested that mutations in ATP1A2 may contribute to pulmonary arterial remodelling through the disturbance of intracellular Ca2+ and K+ concentrations. The gene discussed is ATP1A2; the disease is idiopathic pulmonary arterial hypertension.