Collagen is essential to prevent over‐stretching and rupture, whereas elastin is essential for stretching and recoil of the artery, in order to buffer differences in pressure between systole and diastole.9 Previous postmortem studies identified differences in composition10, 11 and relative amounts12 of collagen and elastin between unaffected Friesian horses, affected Friesian horses and Warmblood horses, that might be related to the predisposition of Friesian horses to aortic rupture. The gene discussed is ELN; the disease is Aortic Rupture.