Genetic Study Links Frailty, Telomere Length to Specific Vascular Diseases

Vascular diseases—including aneurysms, atherosclerosis, and thromboembolism—rise sharply with aging, yet it has remained unclear whether biological aging markers are direct causal drivers or merely correlated phenomena. Traditional observational studies are confounded by lifestyle factors, limiting mechanistic inference. This study applied two-sample Mendelian randomization (MR), which uses genetic variants as lifelong proxies for exposure, to establish causal directionality largely free from environmental confounding.

Researchers assembled GWAS summary data for multiple biological aging exposures: four epigenetic clocks (PhenoAge, GrimAge, HannumAge, HorvathAge), PAI-1 levels, granulocyte proportions, overall and cell-type-specific telomere lengths, the Frailty Index (n=164,610), and facial aging score (n=423,999). Outcome data for nine vascular phenotypes—including thoracic and abdominal aortic aneurysm, aortic dissection, nonruptured cerebral aneurysm, arterial embolism and thrombosis subtypes, atherosclerosis, and other arterial diseases—came from FinnGen Release R12, encompassing up to 463,106 controls. IVW was the primary estimator, with MR-Egger, weighted median, and weighted mode as sensitivity methods. Outlier SNPs were iteratively removed via RadialMR and MR-PRESSO, and FDR correction was applied across all tests.

Three causal pathways survived rigorous post-outlier adjustment and FDR correction. First, a higher genetically predicted Frailty Index was associated with significantly elevated risks of abdominal aortic aneurysm (OR=2.59), atherosclerosis excluding cerebral and coronary sclerosis (OR=2.03), and arterial thromboembolic events (OR=4.03). Second, longer telomere length conferred strong protection against abdominal aortic aneurysm (OR=0.50, P=6.42×10⁻¹²), confirming that telomere attrition is a causal upstream contributor to AAA risk. Third, lower granulocyte proportion was causally linked to increased thoracic aortic aneurysm risk (OR=0.018), suggesting that age-related immune remodeling affecting granulocyte dynamics plays a distinct role in structural aortic failure. Notably, PAI-1 and all four epigenetic clocks showed no significant associations after multiple-testing correction, and facial aging approached significance only for nonruptured cerebral aneurysm without surviving FDR correction.

These findings indicate that biological aging does not uniformly accelerate all forms of vascular disease; rather, distinct aging pathways preferentially drive specific vascular phenotypes. Frailty—reflecting multisystem physiological decline—exerts the broadest vascular risk, while telomere attrition appears to be specifically critical for aortic wall integrity in AAA, and granulocyte dynamics selectively influence thoracic aortic pathology. This causal heterogeneity has implications for targeted prevention: interventions that reduce frailty accumulation may broadly lower vascular risk, while strategies to preserve telomere length or modulate granulocyte activity could specifically reduce aneurysm risk.

Important caveats apply. MR estimates reflect population-level, lifelong genetically determined exposure effects, which differ from short-term clinical interventions. The majority of GWAS data derive from European-ancestry populations, limiting generalizability. Some exposures used relaxed significance thresholds (P<5×10⁻⁶) due to limited genome-wide hits, potentially reducing instrument specificity. Residual pleiotropy cannot be fully excluded despite iterative outlier removal, and the modest case numbers for rare outcomes like aortic dissection reduce statistical power.