Rendu-Osler-Weber Syndrome or Hereditary Hemorrhagic Telangiectasia (HHT): Report of two cases and review of literature.

Rendu-Osler-Weber syndrome, also known as __Hereditary Hemorrhagic Telangiectasia (HHT), is a vascular disorder with a prevalence estimated in one in 5-8.000 individuals. It is a dominant autosomic transmission determining multisystemic vascular dysplasia, which has been mapped to two genes, HHT1 and HHT2, determined by mutations of the endoglin (ENG) gene, localized to the chromosome 9, and by mutations of the activin receptorlike kinase 1 (ALK1) gene, localized on the chromosome 12. The 95% of affected present recurrent epistaxis, with a mean age of first event at about 12 years, generally the nosebleed frequency and severity increase with age and usually it is associated with pulmonary AVM and/or multiple telangiectases of gastrointestinal apparatus, of the hands, face, and oral cavity and others visceral involvement. The first diagnosis of HHT is still based on the presence of clinical signs and family history; for the molecular diagnosis of HHT is necessary sequencing the entire coding regions of the ALK1 and ENG genes. The genetic test is positive not in the 100% of all patients with clinical diagnosis of HHT, but it is also possible not find in the same family group the common mutation. We review the litterature and report 2 cases with oral manifestation, on the tongue and on the inferior lip, without others systemic HHT lesions, treated in our Department for general odontoiatric problems.