Abstract 4138019: eQTL Analysis of the PAH Biomarker CCN2 Identifies a Novel SNP that Associates with Survival

Background: We recently determined that cellular communication network factor 2 (CCN2) (also known as IGFBP8) levels associate with metrics of severity, and survival, in pulmonary arterial hypertension (PAH). While genetic variants that modify CCN2 gene expression have been described, the variants across the genome that associate with CCN2 protein levels in human circulation remain unknown. Research Question: We sought to identify genetic variants associated with circulating levels of CCN2 and to determine those variants’ relationship with clinical severity and survival. Methods: Serum CCN2 was measured by ELISA in subjects from a national sample repository, the PAH Biobank. A genome wide association study (GWAS) for CCN2 (natural log transformed) was performed in White idiopathic PAH (IPAH) PAH Biobank participants (n = 768) using Illumina OMNI5 genotypes in plink after standard quality control. Subsequent exploration of the SNP of interest was conducted in a separate dataset of 687 White PAH participants (n=360 IPAH, n=313 APAH) linked to genetic and clinical data, including REVEAL 2.0 risk score assessment (divided into low, medium, and high-risk levels) and outcomes (the STRIDE (Sitaxsentan To Relieve Impaired Exercise) trials cohort). Results: In the PAH Biobank, using GWAS, we found CCN2 levels were significantly associated with rs9493157 (p = 2.8 x10 -12 ) ( Figure A ). rs9493157 is reported in the Genotype-Tissue Expression (GTEx) portal to be an eQTL for CCN2 expression in the left ventricle. In the STRIDE cohort, the hazard ratio (HR) for death was 1.33 (99% CI 1.03 to 1.72) for participants with one or more T alleles (p=0.027; ( Figure B )). On multivariate analysis, the HR for death was 1.28 (95% CI 0.99 to 1.66; p=0.060). Among subjects with the highest REVEAL2.0 risk, those with a T allele had worse survival than those no T allele, with best survival among those with low a REVEAL2.0 score and no T allele. Conclusions: In White PAH subjects, rs9493157 associates with human levels of serum CCN2, a known biomarker for PAH. While additional studies are warranted, the T allele associates with worse survival and may enhance the prognostic value of the REVEAL2.0 risk score.