COL4A5 and Alport syndrome: Kashtan et al. described the effect of targeted mutations in COL4A5 on the expression of α5(IV) chains in the mouse aorta, suggesting that the presence of a type IV collagen network composed of α5(IV) and α6(IV) chains plays a role in maintaining the integrity of aortic blood vessels.3) In other words, type IV collagen is involved in the mechanism of aortic dissection, and the lack of type IV collagen in Alport syndrome may cause vascular complications earlier than in people without Alport syndrome.