MedGen

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant vascular dysplasia leading to telangiectases and arteriovenous malformations of skin, mucosa, and viscera. Epistaxis and gastrointestinal bleeding are frequent complications of mucosal involvement. Visceral involvement includes that of the lung, liver, and brain. The most frequent form of hereditary hemorrhagic telangiectasia maps to the long arm of chromosome 9. Genetic Heterogeneity of Hereditary Hemorrhagic Telangiectasia See also HHT2 (600376), caused by mutation in the ALK1 gene (ACVRL1; 601284) on chromosome 12q13; HHT4 (610655), mapped to chromosome 7p14; and HHT5 (615506), caused by mutation in the GDF2 gene (605120) on chromosome 10q11. A locus formerly designated HHT3 and mapped to chromosome 5 was found to be in error; see HISTORY. Affected members of the family in which the HHT3 locus was mapped were found to have a mutation in ENG (see MOLECULAR GENETICS) and have been included in HHT1. See also juvenile polyposis/HHT syndrome (175050), caused by mutation in the SMAD4 gene (600993). [from OMIM]

Subacute inflammation of the endocardium. Streptococcus viridans is the usual etiologic agent of subacute bacterial endocarditis. The distinction between ""acute"" and ""subacute"" endocarditis has traditionally been made based on the pathogenic organism and clinical presentation. [from NCI]

Telangiectasias refer to small dilated blood vessels located near the surface of the skin or mucous membranes, measuring between 0.5 and 1 millimeter in diameter. Telangiectasia are located especially on the tongue, lips, palate, fingers, face, conjunctiva, trunk, nail beds, and fingertips. [from HPO]

Hereditary hemorrhagic telangiectasia (HHT) is characterized by the presence of multiple arteriovenous malformations (AVMs) that lack intervening capillaries and result in direct connections between arteries and veins. The most common clinical manifestation is spontaneous and recurrent nosebleeds (epistaxis) beginning on average at age 12 years. Telangiectases (small AVMs) are characteristically found on the lips, tongue, buccal and gastrointestinal (GI) mucosa, face, and fingers. The appearance of telangiectases is generally later than epistaxis but may be during childhood. Large AVMs occur most often in the lungs, liver, or brain; complications from bleeding or shunting may be sudden and catastrophic. A minority of individuals with HHT have GI bleeding, which is rarely seen before age 50 years. [from GeneReviews]

Hereditary hemorrhagic telangiectasia (HHT) is characterized by the presence of multiple arteriovenous malformations (AVMs) that lack intervening capillaries and result in direct connections between arteries and veins. The most common clinical manifestation is spontaneous and recurrent nosebleeds (epistaxis) beginning on average at age 12 years. Telangiectases (small AVMs) are characteristically found on the lips, tongue, buccal and gastrointestinal (GI) mucosa, face, and fingers. The appearance of telangiectases is generally later than epistaxis but may be during childhood. Large AVMs occur most often in the lungs, liver, or brain; complications from bleeding or shunting may be sudden and catastrophic. A minority of individuals with HHT have GI bleeding, which is rarely seen before age 50 years. [from GeneReviews]