Bacterial Symbionts May Prove a Double-Edged Sword for the Sharpshooter

Background: Apolipoprotein E (APOE) and elastin (ELN) are plausible candidate genes involved in the pathogenesis of stroke. We tested for association of variants in APOE and ELN with subarachnoid hemorrhage (SAH) in a population-based study. We genotyped 12 single nucleotide polymorphisms (SNPs) on APOE and 10 SNPs on ELN in a sample of 309 Caucasian individuals, of whom 107 are SAH cases and 202 are age-, race-, and gender-matched controls from the Greater Cincinnati/Northern Kentucky region. Associations were tested at genotype, allele, and haplotype levels. A genomic control analysis was performed to check for spurious associations resulting from population substructure. Results: At the APOE locus, no individual SNP was associated with SAH after correction for multiple comparisons. Haplotype analysis revealed significant association of the major haplotype (Hap1) in APOE with SAH (p = 0.001). The association stemmed from both the 5' promoter and the 3' region of the APOE gene. APOE ε2 and ε 4 were not significantly associated with SAH. No association was observed for ELN at genotype, allele, or haplotype level and our study failed to confirm previous reports of ELN association with aneurysmal SAH. Conclusion: This study suggests a role of the APOE gene in the etiology of aneurysmal SAH. Background Non-traumatic, spontaneous subarachnoid hemorrhage (SAH) affects 16,000 to 17,000 individuals each year in the United States [1-3]. SAH has a 30-day mortality rate exceeding 40%, and surviving patients often demonstrate significant morbidity [2,4]. Over 80% of SAH can be attributed to intracranial aneurysm (IA) rupture. Familial aggregation studies of SAH have consistently identified an Published: 31 July 2007 BMC Medical Genetics 2007, 8:49 doi:10.1186/1471-2350-8-49 Received: 12 December 2006 Accepted: 31 July 2007 This article is available from: http://www.biomedcentral.com/1471-2350/8/49 © 2007 Kaushal et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.