Abstract
BackgroundAdvancing age progressively impacts on risk and severity of chronic disease. It also modifies the epigenome, with changes in DNA methylation, due to both random drift and variation within specific functional loci.ResultsIn a discovery set of 2238 peripheral-blood genome-wide DNA methylomes aged 19–82 years, we identify 71 age-associated differentially methylated regions within the linkage disequilibrium blocks of the single nucleotide polymorphisms from the NIH genome-wide association study catalogue. This included 52 novel regions, 29 within loci not covered by 450 k or 27 k Illumina array, and with enrichment for DNase-I Hypersensitivity sites across the full range of tissues. These age-associated differentially methylated regions also show marked enrichment for enhancers and poised promoters across multiple cell types. In a replication set of 2084 DNA methylomes, 95.7 % of the age-associated differentially methylated regions showed the same direction of ageing effect, with 80.3 % and 53.5 % replicated to p < 0.05 and p < 1.85 × 10–8, respectively.ConclusionBy analysing the functionally enriched disease and trait-associated regions of the human genome, we identify novel epigenetic ageing changes, which could be useful biomarkers or provide mechanistic insights into age-related common diseases.Electronic supplementary materialThe online version of this article (doi:10.1186/s13059-016-1051-8) contains supplementary material, which is available to authorized users.
Highlights
Advancing age progressively impacts on risk and severity of chronic disease
We focused on the a priori functional regions [23], the linkage disequilibrium (LD) blocks of all of the phenotype and disease-related single-nucleotide polymorphisms (SNPs) entered in the genome-wide association study (GWAS) catalogue [24] (8093 curated GWAS SNPs with p value < 1 × 10–7 residing within 2709 distinct LD blocks, ~22.1 % of the genome)
We focused on the DNase I Hypersensitivity site (DHS) due to their broad capacity to act as functional indicators [28]
Summary
Advancing age progressively impacts on risk and severity of chronic disease It modifies the epigenome, with changes in DNA methylation, due to both random drift and variation within specific functional loci. Epigenetic changes associated with the ageing process, DNA methylation, have been identified in a number of studies [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]. While stochastic epigenetic drift does occur [17], non-random changes are seen within specific functional loci, such as increased DNA methylation in the promoters of the target genes of polycomb group proteins [3] and bivalent chromatin regions or poised promoters [4]. DNA methylation changes in peripheral blood may represent this myeloid skewing, biological
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