Hereditary Hemorrhagic Telangiectasia

<p>Hereditary Hemorrhagic Telangiectasia (HHT) or Rendu-Osler-Weber syndrome is a dominantly inheritable rare disease with a prevalence of 1:5000 - 10000 people. The diagnosis of HHT as a rare disease follows the Curaçao Diagnostic Criteria: Nosebleeds (epistaxis) whether spontaneous or recurrent; (multiple) telangiectases at characteristic sites including the lips oral cavity fingers and nose; Internal lesions: arteriovenous malformations (AVMs) or telangiectases in the stomach lungs liver brain and spinal cord; Family history: a first-degree relative with HHT according to these criteria. When a patient meets at least three of these criteria it is considered definite that they have HHT. Nowadays three subtypes of HHT have been identified. HHT type 1 refers to mutations on the endoglin gene ENG; HHT type 2 refers to mutations on the activin A receptor-like type 1 (ACVRL1) gene; and the third one named juvenile polyposis-hereditary hemorrhagic telangiectasia (JPHT or JPHHT) overlap syndrome refers to mutations on the gene MADH 4. There are two other subtypes (HHT-3 and 4) in which the mutations have not yet been completely identified but they are known to be located on the 5q31.3-q32 and 7p14 chromosomal regions respectively.</p>