What is epigenetics?

Genetic information of the DNA is encoded in the sequence of four bases. It is more or less identical in all of our cells and stays constant throughout life. However, expression of specific genes is tightly regulated for each specific cell type. During differentiation and development some genomic regions are permanently activated or inactivated.

Human DNA contains three billion base pairs, making up around 20000 genes (though scientific consensus on the tally continues to fluctuate). Genes are specific sequences of base pairs that provide instructions on how to make proteins - complex molecules that trigger various biological activities and structures. Genes, therefore, provide the instructions for the baseline characteristics of any cell, organism, or individual. For example, variations in human genes lead to different characteristics such as hair color, height, skin color, etc. However, whether, when, how, and where a particular gene is expressed or suppressed is a function of other mechanisms, called epigenetics.

Epigenetics is the study of biological mechanisms that regulate genes by expressing (turning on) or repressing (turning off) them. These various epigenetic marks act "above" or "on top of" the DNA code to influence the expression of genes. 

Because genes provide the instructions for functional proteins to be produced inside our cell (transcription is the first of several steps of DNA based gene expression in which a particular segment of DNA is copied into mRNA by the enzyme RNA polymerase), epigenetic mechanisms such as DNA methylation or modifications in histone tails will affect how the genes are read by cells, and whether the cells should produce relevant proteins.

For example, the COL1A1 gene in DNA is present in all types of cells but “expressed” in skin cells to produce Type 1 Collagen proteins.

Genetics and epigenetics look at different parts of our biology. Genetic information is focused on the sequence of the A, C, T, and G molecules that make up the base pairs in an individual’s DNA, including the presence or absence of specific mutations (changes to the base sequence that can cause variations in the instructions resulting in certain diseases). By contrast, epigenetic information involves the presence or absence of chemical modifications that may affect the processes of gene expression and translation into proteins without altering the DNA sequence itself. The genes an individual receives at birth from his or her parents are the permanent, immutable instructions of their biology, factors over which an individual has no control. By contrast, an individual’s epigenome may change over time based on factors such as aging, exposure to environmental pollutants, and using tobacco, alcohol, or drugs. Many epigenetic modifications have the property of reversibility (for example, a methylated site along the epigenome can become unmethylated and back again). An epigenetic test that seeks to take a snapshot of an individual’s health with regard to behavioral or lifestyle factors would be qualitatively different from genetic testing that examines factors over which an individual has no control. In this sense, epigenetic testing could be considered to simply bring better technology to bear on assessing traditional health factors and behaviors currently obtained from clinical laboratory testing.

With more than 20,000 genes, what will be the result of the different combinations of genes being turned on or off? The possible arrangements are enormous! But if we could map every single cause and effect of the different combinations, and if we could reverse the gene’s state to keep the good while eliminating the bad then we could hypothetically cure cancer, slow aging, stop obesity, and so much more.

However, be wary of self-help claims that exploit epigenetics and seem too good to be true. We recommend you read about the abuse of epigenetics and pseudoscience here.