The mechanistic importance of BMP9 deficiency in portopulmonary hypertension had been recently reported by Paul Yu’s laboratory35, and loss-of-function mutations in BMP9 and GDF2 are identified in PAH and result in reduced BMP9 and BMP10 circulating levels in PAH patients29,65. The gene discussed is BMP10; the disease is Pulmonary arterial hypertension associated with portal hypertension.