Increased expression of syndecan-1 in the media of patients affected by aneurysm; major incidence of thoracic aneurysms in the syndecan-1+/+ population; higher incidence of abdominal aneurysms in SDC 1−/− population; no significant differences in terms of elastin degradation, collagen fiber fragmentation and leukocyte infiltration. This evidence concerns the gene SDC1 and aneurysm.