Indeed, mice deficient in fibulin-1 develop outflow tract and ventricular myocardial abnormalities and defects in peripheral blood vessels that are associated with hemorrhage.9,26 Fibulin-1 is also a prominent constituent of the cardiovascular system, where it is expressed in cardiac valves, cardiac muscle, and blood vessels, including the aorta and coronary and carotid arteries.5,10 Despite extensive expression of fibulin-1 in cardiovascular tissues, often in relation to elastin-containing fibers and elastic laminae,5,10 little is known about its function. Here, FBLN1 is linked to hemorrhage.