The idea is to design a panel including genes mutated in HHT and other vascular alterations with partial phenotype/genotype overlapping with HHT: HHT (ENG, ALK1/ACVRL1, MADH4/SMAD4, BMP9/GDF2), pulmonary arterial hypertension (PAH) (BMPR2, CAV1, ALK1/ACVRL1), cerebral cavernous malformation (CCM) (KRIT1, CCM1, CCM2, PDCD10), and capillary malformation-AVM (CM-AVM) syndrome, caused by mutations in RASA1. This way, the genetic screening includes not only ALK1/ACVRL1 and ENG, but many more genes for almost the same cost. The gene discussed is SMAD4; the disease is pulmonary arterial hypertension.