Background and purpose: Genomewide DNA linkage analysis identified a susceptibility locus for intracranial aneurysm (IA) on chromosome 19q13 in the Finnish population, a region including the kallikrein gene cluster. We investigated the association of single nucleotide polymorphisms (SNPs) in the kallikrein gene cluster with IA in the Finnish population.
Methods: We genotyped 18 haplotype-tagging SNPs spanning a 244 kbp region in the kallikrein gene cluster for 266 Finnish IA cases and 290 Finnish control subjects. In a second phase, we genotyped 2 SNPs (rs1722561 and rs1701946) in an additional set of 102 Finnish IA cases and 102 Finnish control subjects; and in a third phase, we genotyped these 2 SNPs in 156 Russian IA cases and 186 Russian control subjects. Both single-marker and haplotype-based tests of association were performed.
Results: In phase I, SNPs rs1722561 and rs1701946 were significantly associated with IA in the Finnish population for single locus models (rs1722561: P=0.0395; rs1701946: P=0.0253). A 2-SNP haplotype block (rs1722561-rs1701946) identified in phase I was also associated with IA in the expanded Finnish (phase II) data set (asymptotic P=0.012; empirical P=0.019). In the Finnish and Russian combined data set (phase III) with 524 cases and 578 control subjects, the same 2 SNPs (OR: 1.35, 95% CI: 1.14, 1.60; P=0.0005 for rs1722561 and OR: 1.32, 95% CI: 1.12, 1.57; P=0.0011 for rs1701946) were significantly associated with IA. These SNPs are located in the intronic region of KLK8, although linkage disequilibrium could extend from rs268912-rs2250066, a approximately 76-kbp region that includes KLK5-KLK10.
Conclusions: Polymorphisms within the kallikrein gene cluster are associated with IA suggesting that the kallikreins are important candidate genes for IA.