Jones – prism model

One of the reasons that we think epigenetics is so exciting and so applicable to human health is we think it might be a mechanism or something called the developmental origins of health. The DOHaD hypothesis. So developmental origins means that in utero and early life exposures that we talked about might manifest years or decades later as health outcomes.  

And so we’re using epigenetics to try to see what is this sort of memory of these past exposures that sticks around. It’s a concept called biological embedding. The idea that exposures can leave behind a biological residue that can manifest later on in sort of different kinds of health outcomes.  

And the way I like to describe the role of epigenetics in the DOHaD hypothesis is if you imagine the way light hits a prism. So a prism in this case, the prism we’re talking about is the sum of all of your genome and your epigenome together. The genome is static throughout your life time but the epigenome is changeable.  

So if you imagine an exposure like a beam of light. So something happens, you could have poverty or adversity and it’s a specific kind and colour of light and it hits this prism. That prism is the current sum of your genetic and epigenetic status of your cells. And you know that when light hits a prism it refracts into a rainbow. And so the quality of the light and the shape of that prism affect what that rainbow’s going to look like.  

And so in this case, the rainbow is the possible health outcomes later on. So the way we like to think about this idea of biological embedding is that early in life when you have a sensitive period of development, if you have a specific kind or type of light that hits this prism, it can actually alter the epigenome and it can change the shape of that prism. And that in turn of course will change what the rainbow looks like, what the outcomes can be.  

What we think happens is that in certain circumstances, this combination of environment and then that change to the prism can stick around. And so that’s what we look for in our epigenetic research is indicators later on in life of an early life exposure that’s resulted in a change in this prism and alter the possible trajectories in that possible rainbow that you get at the end. 

When I came up with this model, I was thinking to myself, “How do we express the idea that changes to the epigenome result in a change in trajectory but it’s not a deterministic thing?” We’re not getting to saying that changes to the epigenome where you’re going to end up here. There’s still a spectrum, it just changes sort of where the spectrum is. And that’s where I came up with the rainbows. Rainbows sort of make sense when you’re talking about health spectrums. 

I like the prism model because it really describes health in terms of trajectories and not in terms of destinations. So that’s the nice thing about this, the idea of a rainbow because it’s a spectrum of health outcomes from point A to point B. We don’t necessarily know what those points necessarily are. And so specific health outcomes; specific early life exposures may alter the probability that you’re going to end up in one of these two ends of a spectrum but it’s not a deterministic model. It’s not that you have this exposure, you’re going to end up with this particular health outcome. People are complicated. And there are so many other individual factors that affect this but it is about this sort of shift in potential risk or opportunity that I like to use the prism model to describe.