EIF2AK4 and pulmonary venoocclusive disease: Among the pathological sequence variants associated with PAH, mutations in the eukaryotic translation initiation factor 2 alpha kinase 4 (EIF2AK4) gene, in both homozygous or compound heterozygote state, are now established in the diagnostic algorithm of both heritable and sporadic pulmonary veno-occlusive disease (PVOD), a condition characterized by fibrous intimal proliferation of pulmonary septal veins and pre-septal venules recently redefined in ESC/ERS guidelines as PAH with features of venous/capillary (PVOD/PCH) involvement.1