“Genes interact with the surrounding environment and shape new phenotypes, traits and alterations for us to live and survive. Let’s know how does G * E works!”
Imagine you are hiking in the Tibetan mountains with your friend. With each step, the air becomes thinner along with oxygen decrement. But when you see your Tibetan hiking guide, climbing effortlessly. Why so?
“Genes,” popularly known for their protein synthesis function, are the coding DNA sequences. However, only 2 to 3% of the genome is coding. Conversely, the leftover is the non-coding DNA that participates in gene expression.
Both the present factors collectively control which gene to express (genetics) and in which amount (epigenetics). Research suggests that these two alone can’t shape our lives!
For instance, person A is living in a clear and green place while person B is living in a polluted and dirty place, who have more chances to get ill! You know the answer.
The environment, where, when and with whom he or she is living has a significant impact on shaping the traits, phenotypes and characteristics. In this article, we will introduce the concept of gene-environmental interaction and how it works.
Disclaimer: The content presented herein has been compiled from reputable, peer-reviewed sources and is presented in an easy-to-understand manner for better comprehension. A complete list of sources is provided after the article for reference.
Key Topics:
What is a gene?
A gene is a basic hereditary unit made up of the nucleotide. It’s a coding DNA part, each triplet code makes a single amino acid and consequently a protein. Meaning, that whatever proteins we have are made up of genes.
Read more about a gene here: What is a Gene?- Definition, Structure and Function.
Each gene encodes a different type of protein and collectively participates in developmental, reproductive and metabolic activities. The higher the copies of a gene, the higher the protein synthesized!
That’s our gene expression!
In our example, the EPAS1 gene plays a role in adapting to higher altitude living. Over the course of evolution, Tibetans developed a unique variant of the EPAS1 gene, that helps them to live comfortably at a higher altitude.
Even in low oxygen and thin air, due to their higher production of red blood cells, they get enough oxygen. This variant is normally not present in the people living at sea level.
Check out these examples of some genes, their location and function.
| Gene | Location | Function |
| EPAS1 | 2p21 | Regulates responses to low oxygen levels, aiding adaptation to high altitudes. |
| LCT | 2q21 | Encodes lactase, enabling the digestion of lactose in dairy products. |
| PCSK9 | 1p32 | Regulates cholesterol levels by influencing LDL receptor degradation. |
| ACTN3 | 11q13.2 | Produce alpha-actinin-3 protein. Associated with muscle performance. |
| SOD2 | 6q25 | Encodes an enzyme that protects cells from oxidative stress by neutralizing superoxide radicals. |
| APOE | 19q13 | Involved in lipid metabolism and transport; variants are linked to Alzheimer’s disease risk. |
| BRCA1/2 | 17q21.31 (BRCA1) / 13q12.3 (BRCA2) | Repair DNA damage; mutations increase susceptibility to breast and ovarian cancers. |
| TP53 | 17p13 | Functions as a tumor suppressor, regulating cell division and preventing cancer. |
| MC1R | 16q24 | Influences pigmentation, particularly red hair, and sensitivity to UV radiation. |
| FTO | 16q12.2 | Associated with regulation of appetite and predisposition to obesity. |
What is the environment?
In the gene-environmental interaction context, the ‘environment’ here is any external factor such as place, surroundings, society, lifestyle, eating habits, upbringing and trauma and stress. In our example, where the EPAS1 is a gene, the higher altitude or low oxygen condition is an environment.
When a gene interacts with an environment, it shapes unique genotypes or alters gene expression to adapt to the conditions. For instance, here the EPAS1 gene interacted with the higher-altitude for thousands of years and developed a unique genotype of EPAS1 which gives survival potential.
Fascinatingly, it’s only present in those who are interacting with that environment, the Tibetans.
Let’s take another example if someone is living in a higher-temperature area like the Sahara desert. Their skin becomes darker to prevent skin cancer. Let me know in the comment which gene is responsible for skin pigmentation and what is the environment here.
Read more: Epigenetics 101: What is Epigenetics and How Does It Work?
The list of genes, various environments and their interaction is given below.
| Gene | Environment |
| EPAS1 | Higher altitude |
| LCT | Dairy consumption |
| PCSK9 | Low-fat diet |
| ACTN3 | Physical activity (e.g., sprinting) |
| SOD2 | Mild oxidative stress |
| APOE | High-fat diet |
| BRCA1/2 | Exposure to radiation or toxins |
| TP53 | Tobacco smoke |
| MC1R | Sun exposure |
| FTO | High-calorie diet |
What is gene-environment interaction?
Now, we will discuss what the interaction brings to life. I mean, what are the consequences or outcomes? G * E interaction outcomes are neither always good nor always bad. Meaning, it depends on which environment you are facing.
For instance, if you smoke tobacco, the TP53 gene will definitely be negatively impacted. And increases the likelihood of lung cancer. Contrary, for our example a variant of the EPAS1 gene gives strength to live comfortably at a higher altitude and low oxygen area.
Check out the good and bad outcomes of gene-environment interaction.
| Gene | Environment | Interaction |
| EPAS1 | Higher altitude | Enhanced survival in low-oxygen environments |
| LCT | Dairy consumption | Lactase persistence allows the digestion of milk in adults |
| PCSK9 | Low-fat diet | Naturally lower LDL cholesterol, reducing heart disease risk |
| ACTN3 | Physical activity (e.g., sprinting) | Improved athletic performance and muscle strength |
| SOD2 | Mild oxidative stress | Increased antioxidant defense, protecting cells from damage |
| APOE | High-fat diet | Elevated risk of Alzheimer’s disease and cardiovascular issues |
| BRCA1/2 | Exposure to radiation or toxins | Increased susceptibility to breast and ovarian cancers |
| TP53 | Tobacco smoke | Heightened risk of lung cancer due to impaired DNA repair mechanisms |
| MC1R | Sun exposure | Greater susceptibility to melanoma due to less effective melanin production |
| FTO | High-calorie diet | Increased risk of obesity and metabolic disorders |
How does it work?
Now, in this section, we will answer the following questions: How does it shape our lives?
Environmental factors considered for the interactions are surroundings, diet, lifestyle, climate, toxins and social experiences. When a person experiences any, a few or all of these factors, their genes immediately start interacting.
Our genes, made up of DNA, are highly dynamic and sensitive organic elements. Based on the stimuli they experience, they either alter the nucleotide structure or gene expression. Resultantly, newer genotypes or gene patterns are developed.
These patterns or genotypes are experienced as visible traits or characteristics. For instance, a variant of the MAOA gene triggers antisocial and extreme criminal behavior only under the pressure of an adverse social setup and/or an upbringing marked by humiliation and psychological distress.
In conclusion, our genes interact with the environment for our betterment, but it’s not always in our favor. In addition, some of the good interactions also bring adverse consequences and might result in disease conditions.
That we will discuss in another article, in detail.
Wrapping up:
Now you know how Tibetans or people living at higher altitudes survive in low oxygen conditions or why some populations can live comfortably in the extremely hot Sahara desert.
Genetics is fascinating. While it is evident that genes decide our fate, epigenetics and environmental interactions make our ‘fate’ better to survive. For millions of years, our DNA experienced good, bad and extreme environments and made us who we are today.
However, it also brought a few unwanted conditions for us, for instance, cancer or inherited genetic conditions. It happens! Everything has good and bad consequences.
Our genes are always ready to take the challenges and shape our lives, are you ready?
Sources:
Virolainen, S.J., VonHandorf, A., Viel, K.C.M.F. et al. Gene–environment interactions and their impact on human health. Genes Immun 24, 1–11 (2023). https://doi.org/10.1038/s41435-022-00192-6.
Childebayeva A, Jones TR, Goodrich JM, Leon-Velarde F, Rivera-Chira M, Kiyamu M, Brutsaert TD, Dolinoy DC, Bigham AW. LINE-1 and EPAS1 DNA methylation associations with high-altitude exposure. Epigenetics. 2019 Jan;14(1):1-15. doi: 10.1080/15592294.2018.1561117. Epub 2019 Jan 9. PMID: 30574831; PMCID: PMC6380404.
McSwiggan S, Elger B, Appelbaum PS. The forensic use of behavioral genetics in criminal proceedings: Case of the MAOA-L genotype. Int J Law Psychiatry. 2017 Jan-Feb;50:17-23. doi: 10.1016/j.ijlp.2016.09.005. Epub 2016 Nov 4. PMID: 27823806; PMCID: PMC5250535.
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