S22-380 A Tyrosine Kinase Inhibitor (TKI) improves downstream signaling of causal genes for Hereditary Hemorrhagic Telangiectasia and Pulmonary Arterial Hypertension and improves endothelial function The inventors discovered that a known small molecule tyrosine kinase inhibitor may correct the errant signaling pathways in the rare diseases Hereditary Hemorrhagic Telangiectasia (HHT) and Pulmonary Arterial Hypertension (PAH). Edda Spiekerkoetter Md Khadem Ali Adam Andruska