gene = functional unit of DNA expressing a protein
-ome (suffix) = all constituents considered collectively
genome = total complement of functional DNA
epigenome = total complement of additional regulatory biochemicals and biochemical
processes linked to the genome
At least five epigenetic effects have so far been identified, including substances which attach to the DNA or to the RNA expressed by the DNA, and structural changes in the chromosome.
Epigenetic factors are used by mature cells to enable or disable genes as needed to achieve their specialised function.
Environmental toxins, poor nutrition and other stresses can inflict epigenetic changes linked to disease, and if they affect the reproductive cells, the unhealthy epigenome can be inherited by future generations.
As if we didn't have enough concerns about damage to the health of the genome caused by artificial changes in its DNA, science has uncovered another insidious problem in GM organisms.
CRISPR is a favourite DNA-editing tool which can be used to insert genes in precise locations in the genome . However, an experiment on mice found that the desired, precise genetic transformation was accompanied by undesirable changes in the epigenome. These changes were passed down through at least 10 generations.
The epigenetic factor investigated was the attachment of 'methyl' molecules to specific sequences of DNA (a reaction which usually inactivates the gene).
"Disruptions of ... methylation patterns within specific regions of the genome have been associated with disease states such as cancer and neurological disorders" (Farris).
To give an idea of the potential scale of the problem, over 90,000 regions thought to be targets for epigenetic attachment have been identified in the mouse genome.
Such studies in epigenetic effects are carried out with a focus on safely correcting faulty human genes. In other, commercially driven, areas of GM research (food crops, livestock, and gene-drive organisms destined to spread in the environment) the possibility of inconvenient confounding side-effects are ignored.
Our knowledge of the epigenome is in its infancy, and this study looked at one type of epigenetic effect only: the concerns mentioned above may be the tip of a potentially catastrophic epigenetic ice-berg.
Add epigenetic disruption to the list of precision problems in gene editing  and tell your GM-loving regulators to pay attention to all of them. You can contact your MP and MSP using www.writetothem.com
 CRISPR/Cas9 GENE EDITING - March 2016
 THE PRECISION PROBLEM IN GENOME EDITING - June 2021
- M. Heath Farris, et al., 2020, Detection of CRISPR-mediated genome modifications through altered methylations patterns of CpG Islands, BMC Genomics
- CRISPR gene editing unintentionally causes changes in gene regulation, GM Watch 22.12.20
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