 The diagnosis of HHT remained a clinical one until the genetic defects that cause HHT were identified by a research group at Duke University Medical Center , in 1994 and 1996 respectively . In 2000 , the international scientific advisory committee of HHT Foundation International published the now widely used Curaçao criteria . In 2006 , a group of international experts met in Canada and formulated an evidence @-@ based guideline , sponsored by the HHT Foundation International . 
