Epub – Translational Psychiatry: DNA Methylation in the Human Frontal Cortex Reveals a Putative Mechanism for Age-by-Disease Interactions

January 29, 2019

McKinney BC, Lin CW, Rahman T, Oh H, Lewis DA, Tseng G, Sibille E

A consistent gene set undergoes age-associated expression changes in the human cerebral cortex, and our Age-by-Disease Model posits that these changes contribute to psychiatric diseases by “pushing” the expression of disease-associated genes in disease-promoting directions. DNA methylation (DNAm) is an attractive candidate mechanism for age-associated gene expression changes. We used the Illumina HumanMethylation450 array to characterize genome-wide DNAm in the postmortem orbital frontal cortex from 20 younger (<42 years) and 19 older (>60 years) subjects. DNAm data were integrated with existing normal brain aging expression data and sets of psychiatric disease risk genes to test the hypothesis that age-associated DNAm changes contribute to age-associated gene expression changes and, by extension, susceptibility to psychiatric diseases. We found that age-associated differentially methylated regions (aDMRs) are common, robust, bidirectional, concentrated in CpG island shelves and sea, depleted in CpG islands, and enriched among genes undergoing age-associated expression changes (OR = 2.30, p = 1.69 × 10-27). We found the aDMRs are enriched among genetic association-based risk genes for schizophrenia, Alzheimer’s disease (AD), and major depressive disorder (MDD) (OR = 2.51, p = 0.00015; OR = 2.38, p = 0.036; and OR = 3.08, p = 0.018, respectively) as well as expression-based MDD-associated genes (OR = 1.48, p = 0.00012). Similar patterns of enrichment were found for aDMRs that correlate with local gene expression. These results were replicated in a large publically-available dataset, and confirmed by meta-analysis of the two datasets. Our findings suggest DNAm is a molecular mechanism for age-associated gene expression changes and support a role for DNAm in age-by-disease interactions through preferential targeting of disease-associated genes.

McKinney BC, Lin CW2, Rahman T, Oh H, Lewis DA, Tseng G, Sibille E. DNA Methylation in the Human Frontal Cortex Reveals a Putative Mechanism for Age-by-Disease Interactions. Transl Psychiatry. 2019 Jan 29;9(1):39. doi: 10.1038/s41398-019-0372-2. PubMed PMID:30696804, PMCID: PMC6351569.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6351569/

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