Some patients with cerebral aneurysms are deficient in type III collagen.

Polyacrylamide gel electrophoresis of pepsin-digested skin biopsy specimens and carboxymethyl cellulose chromatography of radioactively labelled collagens produced by cultured fibroblasts demonstrated that 7 of 12 patients with congenital cerebral aneurysms were type III collagen deficient. This suggests that some cerebral aneurysms resemble various inherited defects of connective tissue-i.e., Ehlers-Danlos syndrome type IV-in which type III collagen deficiency causes arterial fragility.