 Population studies from numerous areas in the world have shown that HHT occurs at roughly the same rate in almost all populations : somewhere around 1 in 5000 . In some areas , it is much more common ; for instance , in the French region of Haut Jura the rate is 1 : 2351 - twice as common as in other populations . This has been attributed to a founder effect , in which a population descending from a small number of ancestors has a high rate of a particular genetic trait because one of these ancestors harbored this trait . In Haut Jura , this has been shown to be the result of a particular ACVRL1 mutation ( named c.1112dupG or c.1112 _ 1113insG ) . The highest rate of HHT is 1 : 1331 , reported in Bonaire and Curaçao , two islands in the Caribbean belonging to the Netherlands Antilles . 
