Understanding Epigenetics: Q&A with Elvira Isganaitis

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Elvira Isganaitis, M.D., M.P.H., Assistant Investigator and Staff Pediatric Endocrinologist at Joslin Diabetes Center

When we talk about “genetics,” we mean all of the traits inherited from someone’s parents through DNA, including your hair color, eye color, height, and the shape of your nose. But other traits are determined not just through a simple read of your DNA code. Parts of the code that make up your DNA can be read in different ways depending on what sorts of environmental factors you are exposed to. This process is known as epigenetics.

You could think of individual genes as little bits of computer code existing in the DNA that control how the body functions. Those bits of code can be turned on or off either by following instructions dictated by DNA or by responding to different environmental pressures. These environmental pressures are what can cause epigenetic changes. We know from studies that when parents are obese or malnourished during pregnancy, for example, it can lead to epigenetic changes in their babies which can set them up for higher risk for diabetes and other metabolic problems later in life.

In today’s blog post we’ll get a better understanding of what epigenetics is and how it works from Elvira Isganaitis, M.D., M.P.H., Assistant Investigator and Staff Pediatric Endocrinologist at Joslin Diabetes Center and Instructor in Pediatrics at Harvard Medical School.

Speaking of Diabetes: What is epigenetics?

Elvira Isganaitis: Epigenetics is the study of how genes become expressed [or turned on] and turned into proteins but through mechanisms other than your DNA sequence. Epi- means above and -genetics is the gene. And so it’s all that information other than your genetic sequence that goes into expression of genes.

Speaking of Diabetes: What are some examples of things that cause epigenetic changes?

EI: Some epigenetic changes just occur as part of normal human development. If you think about it, you as an individual, every single cell in your body have the same DNA sequence. But something is telling your skin cells to express a very different profile of genes and proteins and enzymes and so on as compared to your gut, your stomach lining. It’s basically all those additional layers of regulatory mechanisms that contribute to those pretty dramatic differences.

But then our interest in particular [in our lab] has been the role of the environment. The idea is that epigenetic mechanisms allow an organism to adapt to changes in the nutritional environment or other environmental changes.

Speaking of Diabetes: What types of environmental pressures can cause epigenetic changes?

EI: Basically, you name it. The list is long and growing. Periods of undernutrition, exposure to famine or just selective undernutrition for diet lacking in protein or iron or other trace minerals, all of those are known to change epigenetic patterns. Conversely, over-nutrition (obesity) can also trigger epigenetic changes. And then from a public health/environmental perspective it’s actually very concerning that a lot of pollutants and chemicals in our environment have also been linked to epigenetic changes.

Speaking of Diabetes: How does epigenetics play a role in conception and pregnancy?

EI: The nutritional characteristics in the period around conception are very important when an infant is conceived. From animal data you can show that having a diet that’s rich in various [healthy] dietary constituents sets up good epigenetic patterns in the embryo that that persist over the lifetime.

The important message about all of this is that optimizing the health of mothers can have multi-generational benefits. And based on interesting data from animals it seems like vitamins and diet and other nutritional constituents improve outcomes. Of course we have to better understand exactly how this all works, but there will be a potential for reversing or optimizing epigenetic patterns to promote metabolic health.

Speaking of Diabetes: What can people do to negate bad effects? Can you reverse them?

EI: That’s the hopeful message. A clinical example is that they’ve been able to look at epigenetic patterns in sperm from sperm donors and show that men with a higher BMI have different patterns [of genes that are turned on] in their sperm and those patterns will change following bariatric surgery. [From person to person, epigenetic changes could be different depending on the underlying genetics], but if we’re comparing a single person pre- and post- surgery you’re ruling out any possible genetic explanation. So that really clinches it, [that those changes are being caused by drastic weight loss]. We also know that exercise changes epigenetic patterns.

It’s a double edged sword. With epigenetics there’s a chance to kind of build on any negative effects that you may have from your genes, but also potentially a chance to reverse certain inherited patterns.

That’s the optimistic message about all of this. At the end of the day it’s not just about the genes that you inherit from your ancestors, but really even the type of lifestyle that you lead and the type of diet that you consume and other lifestyle habits also play a really important role in which genes are being activated and shaping how your body works and how your cells metabolize.

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