Abstract 050: Phenome Wide Association Study of IL6R Variants Identifies a Drug Target for Cardiovascular Disease and Inflammation
Background: Individuals with an interleukin 6 receptor (IL6R) genetic variant not on IL6R blocking therapy have biomarker profiles similar to those treated with IL6R blockers. Thus, studying whether the IL6R variant is protective for a phenotype can inform which diseases may benefit from treatment with IL6R blockade. To test this hypothesis, we performed a Phenome-Wide Association Study (PheWAS) to screen for associations between an IL6R variant and a broad range of phenotypes in the electronic health records (EHR). Methods: We studied veteran participants in the Veteran’s Affairs Million Veteran’s Project using genomic data linked to EHR. We extracted all diagnoses codes and mapped them to phenotype groups using published PheWAS methods. Routine laboratory measurements, e.g. liver function tests, were also extracted. A PheWAS was performed by constructing logistic regression models testing associations between the IL6R variant (Asp358Ala, rs2228145) and 1,866 phenotype groups; linear regression models were constructed to screen for associations between IL6R and 26 routine laboratory measurements. All models were adjusted for age, gender, and race. Significance was reported using false discovery rate ≤0.05 and Bonferroni correction. Results: We studied 342,529 participants; the minor allele frequency of the IL6R variant was 35.3%. IL6R was most strongly associated with a reduced risk of aortic aneurysm (OR 0.91-0.92, 95% CI 0.89, 0.94) (Figure 1). We observed the expected association between IL6R and reduced C-reactive protein. We also observed known side effects of IL6R blockade, elevated transaminases, as well as elevated triglycerides, an initially unexpected result in the early clinical trials. Conclusion: In this proof of concept study, we demonstrate the utility of PheWAS to inform drug effects using the largest US-based biobank study. The strong association with aortic aneurysm corresponded with the newest indication for IL6R blockade to prevent aortic aneurysms due to large vessel vasculitis.