Genotypic variations of type III collagen in patients with cerebral aneurysms.

It has been hypothesized that either qualitative or quantitative abnormalities in type III collagen may be involved in the pathogenesis of cerebral aneurysms. The current study investigated allele frequencies for the type III collagen gene in patients with cerebral aneurysms. A diallelic Ava II polymorphism defined the type III collagen gene. The smaller of the two alleles was found in 11 of 19 aneurysm patients (58%) versus two of 15 controls (13%) (p = .006). The overall frequency of this allele was 0.34 in aneurysm patients versus 0.10 in controls (p = .011). This significant difference in allele frequency suggests that genotypic variations in the type III collagen gene may be etiologically related to aneurysm formation.