Can Global DNA Methylation Be Influenced by Polymorphisms in Genes Involved in Epigenetic Mechanisms? A Review.

Background: Global methylation refers to the total methylation in the DNA and can also be inferred from the Line 1 and Alu regions, as these repeats are very abundant in the genome. The main function of DNA methylation is to control gene expression and is associated with both normal and pathological mechanisms. DNA methylation depends on enzymes that generate the methyl radical (e.g., methylenetetrahydrofolate reductase-MTHFR) and attach this radical to the DNA (DNA methyltransferases-DNMT). Genetic variants such as single nucleotide polymorphisms (SNP) in these genes can lead to changes in the activity or expression of MTHFR and DNMT proteins and consequently influence the DNA methylation profile. This review focuses on studies investigating inter-individual variations in the global DNA methylation profile associated with genetic polymorphisms in the and genes.

Methods: A narrative review was conducted, taking into account articles published in the last 15 years.

Results: It was found that the SNPs rs1801131, rs1801133 and rs1537514 in the gene, rs2241531, rs2228611, rs2228612, rs21124724 and the haplotype rs2288349, rs2228611, rs2228612, rs16999593 in the gene, rs2424909, rs998382, rs6058891, rs6058897, rs4911256, rs2889703 and rs1883729 in the were associated with the level of global DNA methylation, including LINE and Alu regions in different contexts. No association was found with polymorphisms in the gene.

Conclusions: It is concluded that polymorphisms in the and genes may influence the global DNA methylation profile in health, inflammation, tumours and mental illness.