Hereditary hemorrhagic telangiectasia (HHT) is a genetic angiodysplasia affecting multiple organs, characterized by cutaneous, mucosal, and visceral vascular anomalies.

Types

 hereditary haemorrhagic telangiectasia (HHT)
 hereditary haemorrhagic telangiectasia with digestive juvenile polyposis (JHPT)

Synopsis

 vascular lesions (26%) (#12843319#)

• telangiectases
  • mucosal telangiectases
  • conjunctival telangiectases
  • nail bed telangiectases
  • finger pad telangiectases

• digestive angiodysplastic lesions (esophagus, stomach, small intestine colon) (14%) (#12843319#)

• arteriovenous malformations (AVM)
  • pulmonary arteriovenous malformation (PAVM) (4%) (#12843319#)
  • cerebral arteriovenous malformation (CAVM) (3%) (#12843319#)
  • coronary arteriovenous malformation (#9671858#)
  • celiac arterioveinous malformation
  • mesenteric arterioveinous malformation
  • hepatic arterioveinous malformation (and cirrhosis)
  • cerebral arterioveinous malformation
  • spinal arterioveinous malformation

• pulmonary capillary hemangiomatosis (#14991548#)
• arterial aneurysms
• venous varicosities

 hemorrhages

• epistaxis
• subarachnoid hemorrhage
• intracerebral hemorrhage
• digestive hemorrhages

 HHT and digestive juvenile polyposis (JHT syndrome) (MIM.175050) (#11795766#, #9892274#, #8165825#)

• MADH4 (SMAD4) mutations (MIM.600993) at 18q21.1

Etiology

 Locus HHT1: mutation in the gene encoding endoglin (ENG) (MIM.131195) at 9q34.1
 Locus HHT2: mutations in the activin receptor-like kinase-1 gene (ACVRLK1) (MIM.601284) at 12q11-q14
 Locus HHT3 (localization unknown; gene unknown)
 Locus JPHT (juvenile polyposis and HHT): MADH4 mutations (MIM.600993) at 18q21.1