In heritable PAH, bone morphogenetic protein receptor type II mutations may be absent; while mutations of other genes, such as type I receptor activin receptor-like kinase 1 and the type III receptor endoglin (both associated with hereditary hemorrhagic telangiectasia), caveolin-1 and KCNK3, the gene encoding potassium channel subfamily K, member 3, can be detected, instead.
Since the landmark discovery that bone morphogenetic protein receptor type II (BMPR2) mutations cause the majority of cases of familial PAH, investigators have discovered mutations in genes that cause PAH in families without BMPR2 mutations, including the type I receptor ACVRL1 and the type III receptor ENG (both associated with hereditary hemorrhagic telangiectasia), caveolin-1 (CAV1), and a gene (KCNK3) encoding a two-pore potassium channel.
Among them, the identification of bone morphogenetic protein receptor type 2 (BMPR2) as the major predisposing gene and activin A receptor type II-like kinase-1 (ACVRL1, also known as ALK1) as the major gene when PAH is associated with hereditary hemorrhagic telangiectasia.
Familial cases have long been recognised and are usually due to mutations in the bone morphogenetic protein receptor type 2 gene (BMPR2), or, much less commonly, two other members of the transforming growth factor-β superfamily, activin-like kinase-type 1 (ALK1), and endoglin (ENG), which are associated with hereditary hemorrhagic telangiectasia.
Familial cases have long been recognized and are usually due to mutations in the bone morphogenetic protein receptor type 2 gene (BMPR2), or, much less commonly, 2 other members of the transforming growth factor-beta superfamily, activin-like kinase-type 1 (ALK1) and endoglin (ENG), which are associated with hereditary hemorrhagic telangiectasia.
Implications of mutations of activin receptor-like kinase 1 gene (ALK1) in addition to bone morphogenetic protein receptor II gene (BMPR2) in children with pulmonary arterial hypertension.
Exonic mutations in BMPR2 are found in about 50% of patients with familial PAH, and ALK1 mutations are found in a minority of patients with hereditary hemorrhagic telangiectasia and co-existent PAH.