A Look Above the Genes: Epigenetics
What is epigenetics?
Starting with the prefix of the word (epi) which is generated from a Greek origin meaning over and above, epigenetics is the study of the inherited changes in gene function, caused mainly by environmental factors, without any change happening to the DNA sequence [1].
The original definition was stated by the embryologist Conrad Waddington in 1950s, where he stated that ‘’epigenetics is the branch of biology that studies the interaction between genes and their products that bring phenotype into being’’ [3].
To get the full picture of gene expression in cells, genetic sequence must be accompanied with the epigenetic information [2], this information can affect aspects like tissue differentiation, cellular responsiveness, and development.
Despite the similar sequence of genes in body cells, every cell will serve a different function with a different cellular identity because of the epigenetic information[3] , so that every cell will have its own epigenetic patterns [1].
Epigenetics information modification
Epigenetics can affect the genes in multiple ways resulting in silencing a gene (turning it off) or turning the genes on[4]. Some of these modifications are:
- DNA methylation, which is the chemical process where a methyl group (CH3) is added to the DNA, specifically in CpG sites, where cytosine is followed with a guanosine, by DNA methyltransferase enzyme (DMTs) [4]. The added methyl group will affect the structure and appearance of the DNA, resulting in modifications on the gene interaction. Due to its overtime stability, it is considered to be a useful tool in studying diseases, in addition to knowing if the gene is inherited from the father or the mother (imprinting phenomenon)[3].
- Histone modification, which can either be through acetylation or methylation on the amino acid lysine. The acetylation is associated with active chromatin so DNA is transcribed, and vice versa, whereas the methylation can be a marker for either active or inactive chromatin regions[4]. Because histones is part of the chromatin, any histone modification will change chromatin arrangement, eventually affecting if the chromosomal DNA will be transcribed or not[4].
Epigenetics and the environmental factors
Epigenetics and environmental factors are strongly related to each other. During a baby’s development, the genes will gain chemical markers that will affect how much of the gene is expressed as a consequence these different lived experiences will re-arrange these chemical marks (epigenome).
This shall explain the differences in behaviours, health, and achievements between the genetically identical twins[5].
Epigenetics and diseases prevention
Changes in epigenetics can directly affect gene expression, and so many diseases like cancers. Developing an epigenetic analysis can be used to predict therapeutic responses in a unique way, because it will measure the genome effects including the patient’s environmental load, also transgenerational effects can be assessed through this analysis[3].
As a result of this analysis development, we can come to a comprehensive medical understanding of the relation between a patient’s genome, the environmental factors, and the opposed disease risks; which in turn will contribute to disease prevention techniques, and drug development processes[3].
