A rare genetic disorder characterized by nosebleeds and multiple telangiectases that can occur on the skin, mucosal lining and internal organs. The occurrence of pulmonary arteriovenus fistulas in type 3 is greater than type 2 but less than in type 1. It has a different genetic origin to type 1 and 3 (defect on chromosome 5q31.3-q32). See also Osler-Rendu-Weber syndrome 3