Hereditary Haemorrhagic Telangiectasia, sometimes know as Osler Weber Rendu Syndrome,  is a  rare genetic disease which is transmitted in an autosomal dominant fashion. In autosomal dominant conditions this usually means that if one parent has the condition there is a 50% probability of a child of the parents having the disease.

This condition leads to the formation of multiple small areas of abnormal blood vessels forming in the skin and mucus membranes (mouth, nose and gut), known as telangiectasia. In the gut the  abnormal blood vessels are usually just a few millimetres in diameter. When they arise in the gut they ay cause bleeding and anaemia. Lesions may also arise in the nose, lungs liver and brain, where bleeding may have other effects including, nosebleeds, coughing blood (haemoptysis) and intra-cerebral bleeding.

Often the diagnosis is delayed because the condition is not recognised. Many patients may develop classical lesions of telangiectasia on the lips the lips. When lesions in the gut cause bleeding they may be treated endoscopically often with APC.