Introduction

The classic presentation of hereditary hemorrhagic telangiectasia (HHT) includes nose bleeds, dilated and easily bleeding blood vessels of the lips, tongue, and fingers, and gastrointestinal bleeding later in life. It is by no means an isolated mucocutaneous disorder as often presented, but rather a generalized vascular dysplasia, with arteriovenous malformations (AVMs) in multiple organs including the lung, brain, and spinal cord. Vascular malformations have also been reported in the retina, thyroid, diaphragm, liver, pancreas, spleen, kidney, and vertebrae, as well as the major arteries, including the aorta.

The disorder was originally described as early as 1865 by Babington in one individual. Henri Rendu, a French internist, first described the combination of telangiectasia and familial epistaxis as an entity distinct from hemophilia in 1896. There followed a series of cases reported by Sir William Osler (1901); the dermatologic manifestations were detailed by Frederick Parkes Weber (1907). These three names appear in various combinations in the title for the disorder. It was Osler's Chief Resident, Frederick Hanes (1909), who coined the term hereditary hemorrhagic telangiectasia in a break from the eponymous tradition.

Genetic basis

Hereditary hemorrhagic telangiectasia is inherited in an autosomal dominant pattern with high penetrance; its incidence is now estimated to be as high as 1 in 10 000. Two different loci for HHT have been identified: HHT1 at chromosome region 9q33–q34 encodes endoglin, a TGF-beta binding protein (Shovlin et al., 1994; McAllister et al.