What is the pathophysiology of Osler-Weber-Rendu disease (OWRD) (hereditary hemorrhagic telangiectasia [HHT])?

Updated: Oct 06, 2020
  • Author: Klaus-Dieter Lessnau, MD, FCCP; Chief Editor: Vincent Lopez Rowe, MD  more...
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Answer

OWRD (ie, HHT) is the first identified human disease caused by defects in a TGF-β superfamily receptor. [14, 15] The clinical manifestations of OWRD are caused by the development of abnormal vasculature, including telangiectasias, AVMs, and aneurysms. Unaffected areas show normal vessel architecture on ultrastructural analysis. [16] Thus, researchers postulate that an initiating event combined with abnormal repair results in the lesions. [17]

Defects in the endothelial cell junctions, endothelial cell degeneration, and weakness of the perivascular connective tissue are thought to cause dilation of capillaries and postcapillary venules, which manifest as telangiectasias. Most commonly, telangiectasias involve the mucous membranes, as well as the skin, the conjunctiva, the retina, and the GI tract.

AVMs are abnormal tortuous vessels with both arterial and venous components. Larger AVMs can cause left-to-right shunting and, if sufficiently large, may contribute to high-output heart failure. Loss of the muscularis layer and disturbance of the elastic lamina of vessel walls may also give rise to aneurysms in multiple organ systems. AVMs are found in the lungs, brain, and liver.


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