If you ever want to get involved in something that is intricate, mysterious, and which you will never fully understand in your entire lifetime — even if you study it EVERY DAY — study genetics. The fact that a tiny, double-helical strip of molecules strung together is essentially the MAP OF LIFE boggles the mind. DNA is small enough to fit in the nucleus of a tiny cell, too small to view with the naked eye. Yet, if you unpack it from its supercoiled structure, you can actually see it without a microscope.
More importantly, the idea that your DNA has all that’s needed for a living organism to develop from a single cell to a fully-differentiated, multi-systemic creature that can survive is just… awesome. What’s even more fascinating is that there’s still SO MUCH we don’t know about DNA.
But while most people (and much of science) have focused on standard genetics and the study of DNA, there’s a whole other world to explore, one that’s turning out to be extremely important: Epigenetics.
What is Epigenetics?
With the release of my book The Refugee, it occurred to me that most people aren’t familiar with epigenetics, an important theme throughout the book (and the series). So here’s a little genetics primer:
DNA is the code that creates proteins that make things happen in our body. For example, when we approach puberty, certain genes in our DNA “turn on” and code for proteins that regulate our endocrine systems, allowing for estrogen and testosterone to increase. This is why girls develop breasts and boys get taller and deeper-voiced.
But how does this happen? Who decides what genes get turned on and off, and when? This is where epigenetics comes in.
Epigenetics examines not the DNA and genes themselves, but how the genes are turned on, turned off, or otherwise altered in their expression. In other words, epigenetics examines how genes are regulated without any change in the DNA code itself. Our genes are all there in our cells, but it’s epigenetics that decides what the genes will do. It does this by altering the way the DNA is packaged in the cell as well as with compounds that bind directly to the DNA (e.g. a methyl group can bind to DNA, a process known as methylation).
Photo courtesy of Nature article by Sun et al, Pediatric Research (2013) 73, 523–530
Epigenetics has gained more attention in the last several years. For ages, it was assumed that “code is key,” i.e. that your DNA code determined important aspects of your biology, including your health, your appearance, and the aging process. Now we know that epigenetics plays a big role in these areas. Some examples:
- Identical twins, with identical DNA, can turn out differently. One can develop Alzheimer’s while the other does not, or they can look slightly different.
- All cells in our body have the same DNA, but epigenetic mechanisms tell a cell whether to become a skin, liver, or pancreatic cell.
- An epigenetic change can “turn off” a tumor suppression gene, which can lead to uncontrolled cellular growth (i.e. tumor).
- In Fragile X, a genetic disorder that leads to intellectual/developmental disability, one only gets the full disorder if the DNA is methylated, which “turns off” the gene that creates an important and necessary protein. It’s this addition of the methyl group that’s the issue, not the abnormality in the code itself. I actually worked on a Fragile X project many years ago.
- Even the aging process itself is considered by some to be an epigenetic process. After all, something tells our cells to stop producing melanin in our hair, for example, resulting in gray hair.
What’s really amazing is that epigenetic states can be passed on to one’s offspring. But that’s a whole other topic.
Here are a few articles on epigenetics, if you’re interested: