A GENE FOR HEREDITARY HEMORRHAGIC TELANGIECTASIA MAPS TO CHROMOSOME 9Q3

Hereditary haemorrhagic telangiectasia (HHT) is an autosomal dominant vascular disorder that is characterized by frequent nosebleeds, mucocu taneous telangiectases and vascular malformations that cause recurrent haemorrhage and arteriovenous shunting. Linkage analyses in one kindr ed identified an HHT locus on the long arm of chromosome 9 (maximum mu ltipoint lod score = 6.20 between D9S60 and D9S61). Analyses in two ot her unrelated HHT families demonstrated that the disease in one was no t linked to the locus on chromosome 9q3. We conclude that HHT is a gen etically heterogeneous disorder. Based on its map location (9q3) and e xpression in vascular tissues, type V collagen is a possible candidate gene for HHT.