Guo Y, Li D, Hu Y. Appraising the associations between
systemic iron status and epigenetic clocks: A genetic correlation and bidirectional Mendelian Randomization study.
Am J Clin Nutr 2023:S0002-9165(23)48897-1. [PMID:
37146762 DOI:
10.1016/j.ajcnut.2023.05.004]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 04/25/2023] [Accepted: 05/01/2023] [Indexed: 05/07/2023] Open
Abstract
BACKGROUND
Genetic correlations and bidirectional causal effects between systemic iron status and epigenetic clocks have not been fully investigated, although observational studies have suggested systemic iron status is associated with human aging.
OBJECTIVES
We explored the genetic correlations and bidirectional causal effects between systemic iron status and epigenetic clocks.
METHODS
Leveraging large-scale genome-wide association study summary-level statistics for four systemic iron status biomarkers (ferritin, serum iron, transferrin, transferrin saturation) (N = 48,972) and four measures for epigenetic age (GrimAge, PhenoAge, IEAA, HannumAge) (N = 34,710), genetic correlations and bidirectional causal effects were estimated between them mainly by applying linkage disequilibrium score (LDSC) regression, Mendelian randomization (MR), and MR based on Bayesian model averaging (MR-BMA). The main analyses were conducted employing multiplicative random effects inverse variance weighted MR. MR-Egger, weighted median, weighted mode, and MR-PRESSO were performed as sensitivity analyses to support the robustness of causal effects.
RESULTS
The LDSC results illustrated genetic correlations (Rg) between serum iron and PhenoAge (Rg = 0.1971, p = 0.048) and between transferrin saturation and PhenoAge (Rg = 0.196, p = 0.0469). We found that increased ferritin and transferrin saturation significantly increased all four measures of epigenetic age acceleration (all p < 0.0125, beta > 0). Each standard deviation genetically increases in serum iron only significantly associated with increased IEAA acceleration (beta = 0.36, 95% CI 0.16-0.57, p = 6.01E-04) and increased HannumAge acceleration (beta = 0.32, 95% CI 0.11-0.52, p = 2.69E-03). Evidence showed a suggestively significant causal effect of transferrin on epigenetic age acceleration (all 0.0125 < p <0.05). Additionally, reverse MR study indicated no significant causal effect of epigenetic clocks on systemic iron status.
CONCLUSIONS
All four iron status biomarkers had a significant or suggestively significant causal effect on epigenetic clocks, whereas reverse MR studies did not.
Collapse