Any primary pulmonary hypertension in which the cause of the disease is a mutation in the SMAD9 gene. The disease is pulmonary hypertension, primary, 2 (Monarch Disease Ontology entry MONDO_0014134). Also known as: SMAD9 primary pulmonary hypertension, primary pulmonary hypertension caused by mutation in SMAD9, pulmonary hypertension, primary, type 2.