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DNA methylation modifies the human genome, and can be a cause of many diseases. Read more below to learn how it affects your health.


Methylation in humans affects the cytosine (C) nucleotide. It is the process by which a methyl group (a carbon atom with 3 hydrogen atoms attached to it) connects to the cytosine nucleotides (R).

DNA methylation causes a crucial modification to the genome that is involved in regulating many cellular processes. These processes include chromosome structure and stability, DNA transcription, and embryonic development (R).

In normal cells, it ensures the proper regulation of gene expression and gene silencing (R).

Types of Methylation

1) DNA Hypermethylation


A healthy body has a certain level of methylation. Irregular and over-methylated DNA can change a gene, preventing it from producing what it’s meant to. Changes in the placement of methyl groups can cause diseases (R).

Some researchers have even used the amount of methylation in certain genes as a biological clock, as it occurs in individual genes is proportional to age. The implications include, but are not limited to:

  • Causes cancer
  • Lowers immune system function
  • Damages brain health
  • Lowers energy and exercise
  • Quickens aging

It can inactivate certain tumor-suppressor genes and stop the expression of MRNAs that play a role in tumor suppression (R).

Additionally, external, environmental factors can alter methylation. In other words, while abnormal methylation in DNA can replicate itself and be passed down, this balance can also be altered by everything around us (R).

2) DNA Hypomethylation


If there is not a high enough level of methylation in the body, it can cause genomic instability and cell transformation (R).

3) DNA Demethylation

DNA demethylation can also play a role in the formation of tumors. It happens in early embryos and is essential for stem cells to be able to differentiate into different cell types (R).

Demethylation removes the modification of the nucleotides from DNA (R).


  • The most striking feature of vertebrate DNA methylation patterns is the presence of CpG islands, that is, unmethylated GC-rich regions that possess high relative densities of CpG (R).
  • However, a significant fraction of all human CpG islands is prone to progressive methylation in certain tissues during aging (R).
  • Cytosine deaminases carry out demethylation, converting 5mC to thymine, followed by T-G mismatch repair that specifically replaces thymine with cytosine (R).
  • TET family hydroxylases oxidizing 5mC may also participate in active DNA demethylation (R).
  • Either transcription persists leading to restoration of the unmethylated CpG island flanked by methylated non-island-flanking DNA, or other mechanisms extinguish transcription in the embryo and this invites de novo methylation of the CpG island and its flanks (R).

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  • Zoltan

    And what to do with? If my methylation doesn’t works well?! How to fix it?

  • Natcha

    Effects of methylation could be gene-specific. You might just want to have a post about epigenetics or epigenetic modifications overall, but there are so many details that are harder for most readers to understand if most of them are trying to synthesize it into actionable steps. Also, there are also methylations of neurotransmitters and other gene products that need to be taken into account.

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