Abstract 50: Evaluation of Candidate Polymorphisms for Association With Brain Arteriovenous Malformations and Intracranial Hemorrhage in Hereditary Hemorrhagic Telangiectasia

Introduction: Brain arteriovenous malformations (AVM) are an important cause of intracranial hemorrhage (ICH) in young adults. Most are sporadic, but also occur in inherited diseases such as hereditary hemorrhagic telangiectasia (HHT). ICH presentation of brain AVM in both sporadic and HHT cases is a marker of high ICH risk. In order to investigate whether the same genetic modifiers influence sporadic and HHT brain AVM, we evaluated candidate genetic polymorphisms reported as associated with sporadic brain AVM, with ICH presentation or ICH during clinical course, in HHT patients. Methods: We genotyped 8 polymorphisms ( APOE E2/3/4 [rs7412, rs429358], ANGPTL rs116724, EPHB4 rs314308, IL6 -174G>C [rs1800795], IL1B -31T>C [rs1143627], ITGB8 rs10486391, TNF -238G>A[rs361525]) in 753 Caucasian HHT patients enrolled by the Brian Vascular Malformation Consortium (BVMC). Genotypes were collapsed into risk allele carriers vs. other for analysis, as published for sporadic AVM. APOE E2/3/4 haplotypes were assigned based on genotypes of the 2 APOE polymorphisms. Association of genotype with phenotype was evaluated by multivariable logistic regression adjusted for age, gender and accounting for family clustering. We used a nominal significance threshold of p=0.05, requiring the same direction of effect as in sporadic brain AVM (odds ratio for risk genotype [OR]>1). Results: Among 753 HHT patients, 155 (21%) had brain AVM, of whom 26 (17%) presented with ICH. Two additional brain AVM patients had ICH during follow-up. None of the 7 variants (6 single nucleotide polymorphisms and APOE haplotype) were significantly associated with brain AVM (OR=0.6-1.3), with ICH presentation of brain AVM (OR=0.4-1.9), or with any brain AVM ICH in HHT patients (OR=0.5-2.1). Conclusions: Common genetic variants previously reported to be associated with sporadic brain AVM were not associated with brain AVM nor with ICH in the BVMC HHT cohort, suggesting different genetic modifiers may influence sporadic and HHT brain AVM. However, the number of ICH cases in the cohort is small, so the confidence intervals are wide and we cannot rule out clinically important associations. The BVMC is enrolling additional HHT patients to expand the cohort and increase power for association analyses.