Abstract WMP80: Pleiotropy Analyses Of Between Intracerebral Hemorrhage And β-amyloid Related Phenotypes

Abstract

Introduction: Combining biologically related traits in genome-wide association studies has been demonstrated to increase the power for genetic discovery and to identify new genes associated with intracerebral hemorrhage (ICH). Given the pathological relationship between lobar ICH and cerebral amyloid angiopathy (CAA), and between the latter and levels of CSF amyloid-β 42 (CSF-Aβ 42 ), we leveraged genetic predisposition for lower CSF Aβ 42 levels, as a proxy phenotype for CAA, in pleiotropy analysis for lobar ICH. Methods: We used publicly available GWAS data for Aβ 42 levels (n=3,146) and for lobar ICH (n=1,813) from the International Stroke Genetics Consortium. To evaluate the association between lobar ICH risk and CSF-Aβ 42 , we computed a polygenic risk score (PRS) for CSF-Aβ 42 in lobar ICH patients. We then applied multi-trait analysis of GWAS (MTAG) for pleiotropy analysis of lobar ICH and CSF-Aβ 42 . Gene-level associations based on the MTAG result were further tested using S-Predixcan. Results: We found a significant association between CSF-Aβ 42 PRS and ICH risk (β = -0.35; P = 0.04). MTAG analyses identified one novel near-genome-wide significant association within CDH9 (rs1007589; minor allele frequency=0.09; MTAG β = -0.12 and P = 5.4x10 -8 ; lobar ICH β = 0.34 and P = 2.4x10 -3 ; CSF-Aβ 42 β = -0.03 and P = 4.5x10 -6 ). According to the BRAINEAC brain tissue gene expression database, rs1007589 is significantly associated with increased expression of CDH9 in both temporal and occipital cortices. Discussion: This pleiotropy analysis was designed to identify genetic determinants of lobar ICH driven by amyloid-related mechanisms. We identified a variant in one novel gene associated with both traits, CDH9 , which causes differential expression in two brain regions characteristically affected by vascular amyloid pathology. CDH9 encodes for one subtype of the cadherin superfamily, which regulates intercellular adhesion. Cadherins have been involved in blood-brain barrier integrity and are elevated in AD patients. Further analyses are warranted to understand the effects of the variant on the pathogenesis of ICH and its clinical significance.