Epigenome-Wide Search for Association of Serum 25-Hydroxyvitamin D Concentration with Leukocyte DNA Methylation in a Large Cohort of Older Men

Abstract

Aim: We aimed for an epigenome-wide identification of vitamin D-associated CpG sites in leukocyte DNA. Materials & methods: Infinium HumanMethylation450BeadChip measurements in 402 Caucasian older men were evaluated for significant association with 25-hydroxy-vitamin (25(OH)D) using Spearman’s correlation and median regression to adjust for confounding variables. A cross-validation approach as well as a bootstrapping procedure were implemented to determine the replicability of significant associations. Multiple testing was corrected for by Benjamini–Hochberg or Bonferroni. Results: Although in the screening subcohorts significant associations of DNAm with 25(OH)D were observed in the validation cohorts these associations were not replicated after adjustment for potential confounders. At none of the 361,945 CpGs a significant association of DNAm with 25(OH)D was found in all 100 random bootstrap samples, but in comparison at 462 CpGs for the well-established association with age. Conclusion: Leukocyte DNAm was not associated with 25(OH)D levels after validation and consideration of confounders.

Keywords::

• 25(OH)D
• bootstrapping
• cohort study
• cross-validation
• DNA methylation
• epigenetics
• elderly
• humans
• vitamin D

Acknowledgements

The authors thank the microarray unit of the DKFZ Genomics and Proteomics Core Facility, especially M Schick and R Fischer, for providing the Illumina Human Methylation arrays and related services and U Benscheid for helpful comments on programming. The authors are grateful to the statistician reviewer, whose comments helped to improve the manuscript.

Financial & competing interests disclosure

This work was supported in part by grants from the Baden-Württemberg State Ministry of Science, Research and Arts and by the German Federal Ministry of Education and Research. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Ethical conduct of research

The authors state that they have obtained appropriate institutional review board approval or have followed the principles outlined in the Declaration of Helsinki for all human or animal experimental investigations. In addition, for investigations involving human subjects, informed consent has been obtained from the participants involved.

Additional information

Funding

This work was supported in part by grants from the Baden-Württemberg State Ministry of Science, Research and Arts and by the German Federal Ministry of Education and Research. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript.