Genetic studies in familial pulmonary arterial hypertension (FPAH) have revealed heterozygous germline mutations (one mutated copy and one normal copy) in the bone morphogenetic protein type II receptor (BMPR2), a receptor for the transforming growth factor (TGF)-beta/bone morphogenetic protein (BMP) family. This evidence concerns the gene BMPR2 and heritable pulmonary arterial hypertension.