Epigenome-wide analysis of DNA-methylation signatures following climate-related disasters.
BACKGROUND: Floods and tropical cyclones (TCs), two of the most frequent and costliest climate-related disasters worldwide, have been linked to sustained health risks extending beyond acute hazards. However, evidence on the underlying epigenetic mechanisms remains scarce. We aimed to characterize DNA methylation patterns associated with exposure to floods and TCs of varying intensities. METHODS: We collected peripheral blood samples from 479 women (132 twin pairs and 215 of their sisters) across Australia. Blood-derived DNA methylation profiles were assessed using the Illumina HumanMethylation450 BeadChip array. Daily flood and TC exposure data for the 6 years preceding each blood draw were obtained from the Dartmouth Flood Observatory and the International Best Track Archive for Climate Stewardship, respectively, and linked to participants based on residential addresses. Using a within-sibship analytical framework that accounted for shared familial factors and other relevant covariates, we examined associations between flood and TC exposures of varying intensities and site-specific methylation at each cytosine-guanine dinucleotide (CpG). Differentially methylated regions (DMRs) were identified using a combination of the comb-p and DMRcate algorithms. RESULTS: There were 164 CpGs and 219 DMRs associated with flood and TC exposures (Bonferroni-adjusted p value < 0.05), mapping to 242 genes enriched in pathways related to inflammation and immune regulation. These genes have been implicated in a wide range of human diseases or phenotypes. The number of differentially methylated CpGs increased with more recent and higher-intensity exposures. Intensity-dependent gene regulation was observed, with genes such as AMT and C22orf45 consistently implicated across various exposure levels, whereas RNF39 and ACY3 emerged only at higher intensities. CONCLUSIONS: Exposures to floods and TCs were associated with differentially DNA methylated signals across the human genome, exhibiting intensity-dependent patterns. The identified signals and related gene pathways may shed light on the biological mechanism underlying the profound health effects of climate-related disasters.