1847PMendelian randomization study of Alzheimer’s disease and lung cancer

Abstract Background Observational studies show that Alzheimer’s disease (AD) and lung cancer is negatively associated in both directions. However, whether there is a causal relationship between AD and lung cancer remains uncertain. Mendelian Randomization (MR) is a novel approach for the assessment of causality, using genome-wide significant single-nucleotide polymorphisms (SNP) as instrument variables (IV) to eliminate the bias caused by confounders. In this study, we utilized a bi-directional two-sample MR analysis to estimate the potential causality between AD and lung cancer. Methods The genome-wide association study (GWAS) summary data of AD and lung cancer were derived from the International Genomics of Alzheimer’s Project (IGAP,17,008 AD cases and 37,154 controls) and the International Lung Cancer Consortium (ILCCO, 11,348 lung cancer cases and 15,861 controls), respectively. We performed a bi-directional two-sample MR analysis to determine the causal relationship between AD and lung cancer. To be specific, Inverse-Variance Weighted (IVW), MR-Egger and Weighted Median methods were utilized for deriving causal estimates. Single SNP analysis and leave-one-out analysis were also conducted to identify if a single SNP is driving the association. We also performed the MR-Egger regression and MR-PRESSO analysis for the evaluation of horizontal pleiotropy. Results There was no causal relationship between AD and lung cancer in bi-directional MR. The results of Single SNP analysis and leave-one-out analysis indicated that no single SNP was driving the association. No directional horizontal pleiotropy was detected in the MR-Egger regression analysis. The MR-PRESSO analysis did not detect horizontal pleiotropy. There was no evidence for violations of MR assumptions in the sensitivity analysis. Table . 1847P Mendelian randomization estimates of the causality Exposure Outcome Inverse Variance Weighted MR Egger Weighted Median OR (95%CI) P-value OR (95%CI) P-value OR (95%CI) P-value Alzheimer’s Disease Lung Cancer 1.040 (0.965-1.121) 0.299 1.033 (0.890-1.199) 0.676 0.999 (0.902-1.106) 0.980 Lung Cancer Alzheimer’s Disease 0.919 (0.794-1.062) 0.253 1.223 (0.597-2.504) 0.637 0.920 (0.836-1.013) 0.091 Conclusions We found no causality between AD and lung cancer through the two-sample MR analysis. However, further study is warranted. Legal entity responsible for the study The authors. Funding National Key R&D Program of China (Grant No. 2016YFC0905500, 2016YFC0905503). Disclosure All authors have declared no conflicts of interest.