Activin A receptor type II-like 1 (Activin Receptor-Like Kinase I, ACVRL1 or ALK1) is a gene that encodes a cell surface receptor of the serine/threonine kinase type. The protein is important for proper development of blood vessels. Mutations in the gene are associated with vascular malformations.


Synonyms for the gene: HHT2, ORW2, SKR3, TSR-1, ACVRLK1, TGF-beta superfamily receptor type I


Gene location: 12q11-q14


Ligand: transforming growth factor beta


Inheritance: usually autosomal dominant (meaning that a parent is affected)


A patient who carries a mutation in ACVRL1 (ALK1) may develop:

(1) hereditary hemorrhagic telangiectasia (HHT)

(2) pulmonary arterial hypertension

(3) cerebral or other visceral arteriovenous malformations in patients who do not meet the criteria for HHT


Features of ACVRL1-related PAH:

(1) younger age at onset and diagnosis

(2) worse prognosis


Testing involves both sequence analysis and duplication/deletion analysis.


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