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All Diseases > Hereditary Hemorrhagic Telangiectasia
Hereditary Hemorrhagic Telangiectasia (HHT)
Alternative Names: Brain Arteriovenous Malformation (BAVM)
Disease Category: Brain Vascular Malformations
A rare inherited disease with an estimated prevalence of 1 in 5000, characterized by abnormal blood vessels. HHT is caused by mutations in three known genes; Endoglin (ENG), Activin A Receptor Like Type 1 (ACVRL1) and SMAD4, with dominant inheritance. The abnormal blood vessels consist of direct artery to vein connections, with the small ones called telangiectasia and the large ones called arteriovenous malformations (AVMs). Most patients have telangiectasia on the lining of the nasal passages and/or the gastro-intestinal tract, resulting in chronic bleeding and anemia. At least 50% will also have AVMs in the internal organs (commonly in the lung, liver, brain) which can lead to life-threatening hemorrhage, stroke, heart failure and liver disease.