Birth weight and risk of cerebral aneurysm: A multivariable Mendelian randomization study.

Background: Birth weight has been linked with various health outcomes. The association between birth weight and cerebral aneurysm remains unknown.

Methods: The two-sample Mendelian randomization (MR) approach was used to evaluate the causal effect of birth weight on cerebral aneurysm based on genome-wide association studies (GWAS), comprising 261,932 UKB participants for birth weight and 204,060 FinnGen participants for cerebral aneurysm. The inverse variance weighted (IVW) method was used as the primary method. Alternative methods were used for comparison. Sensitivity analysis was conducted to evaluate the robustness of the results. Multivariable MR (MVMR) was further conducted to evaluate the direct effect of the birth weight on cerebral aneurysm.

Results: The IVW detected a causal association between higher birth weight and increased risk of cerebral aneurysm (OR = 0.521, 95% CI = 0.356 ∼ 0.763, P = 7.88 × 10), which was supported by alternative MR models. Sensitivity analysis did not find any evidence of heterogeneity or pleiotropy. MVMR further identified a direct effect of birth weight on cerebral aneurysm, independent of obesity-related traits or smoking.

Conclusion: This MR study found evidence of the association between birth weight and cerebral aneurysm, providing novel insight into the etiology of cerebral aneurysm, indicating the promising role of birth weight as a marker for screening populations at higher risk of cerebral aneurysm.