It is alsounderstood that primary disorders of solid organs including the liver, LV, andkidney can result in result in PoPH, Group 2 PH, and Group 5 PH, respectively.The observation that circulating BMP9, a hepatically-synthesized BMPR2 ligand, isdecreased in PoPH compared to cirrhosis without PH suggests a direct mechanisticlink between PoPH and BMPR2 insufficiency [218, 219]. This evidence concerns the gene GDF2 and Pulmonary arterial hypertension associated with portal hypertension.