J Med Genet 43:97-110 doi:10.1136/jmg.2005.030833
  • Review

Hereditary haemorrhagic telangiectasia: current views on genetics and mechanisms of disease

  1. S A Abdalla1,
  2. M Letarte2
  1. 1Department of Laboratory Medicine and Pathobiology, St Michael’s Hospital Toronto, Canada
  2. 2Cancer Research Program, The Hospital for Sick Children, Department of Immunology and Heart & Stroke Richard Lewar Center of Excellence, University of Toronto
  1. Correspondence to:
 Dr Salma A Abdalla
 Department of Laboratory Medicine and Pathobiology, St Michael’s Hospital, CC-2009, 30 Bond Street, Toronto, Ontario M5B 1W8, Canada; mablab{at}
  • Received 16 January 2005
  • Accepted 28 April 2005
  • Revised 27 April 2005
  • Published Online First 6 May 2005


Hereditary haemorrhagic telangiectasia (HHT) is an autosomal dominant disorder characterised by epistaxis, telangiectases, and multiorgan vascular dysplasia. The two major types of disease, HHT1 and HHT2, are caused by mutations in the ENG (endoglin) and ACVRL1 genes, respectively. The corresponding endoglin and ALK-1 proteins are specific endothelial receptors of the transforming growth factor β superfamily essential for maintaining vascular integrity. Many mutations have been identified in ENG and ACVRL1 genes and support the haploinsufficiency model for HHT. Two more genes have recently been implicated in HHT: MADH4 mutated in a combined syndrome of juvenile polyposis and HHT (JPHT), and an unidentified HHT3 gene linked to chromosome 5. Current knowledge on the genetics of HHT is summarised, including the pathways that link the genes responsible for HHT and the potential mechanisms underlying the pathogenesis of the disease.


  • Conflicts of interest: none declared