Archives for posts with tag: DNA

From the Montreal Gazzette:

Early childhood living conditions provoke biological changes in genes leading to DNA “memory” that can last a lifetime, an international study has found.

Experts have already noted that income, education and neighbourhood resources can have a dramatic effect on children’s health, and that a poor socio-economic environment in infancy can translate into a higher risk of adult disease and early mortality.

But a study published online Thursday in the International Journal of Epidemiology suggests that early experience works changes that are far more than skin deep.

The environment of early childhood influences brain and biological development and leaves a “memory” in the genetic code that affects the way genes function, say researchers from McGill University, the University of British Columbia and the UCL Institute of Child Health in London, England.

“Biological embedding” may help explain why health disadvantages linked to a lower socio-economic origin — including obesity, mental health problems, heart disease, diabetes and other chronic illnesses — can last a lifetime even if living conditions improve later.

The team focused on a small sample — 40 men — from the ongoing British cohort study, which has followed 10,000 people born in March 1958 from birth onward.

The team looked at the DNA of men aged 45 who came from one of two economic extremes: children whose fathers were unskilled workers; and those whose dads were company CEOs and Oxford/Cambridge graduates.

“We wanted to sample from the extremes so that if there was an epigenetic (gene) signal, it would be as clear as possible — and that’s in effect what emerged,” said Clyde Hertzman, director of the UBC-based Human Early Learning Partnership and an author of the study.

After looking at control areas of 20,000 genes, researchers found twice as many genetic differences (1,252 changes) in those brought up in wealth and comfort compared to those raised in poor living conditions (545 changes), making a link between the economics of early life and the biochemistry of DNA.



From Living On Earth (portions of an interesting radio discussion of the new field of epigenetics which “demonstrates how environmental factors can also determine diseases in our future, and in our children and grandchildren’s future”):

GELLERMAN: A failed laboratory experiment led to an accidental discovery that is changing the way we understand genetics. It happened in Professor Michael Skinner’s lab at Washington State University. Skinner was studying DNA—the genetic code of life…when he found, by chance, that environmental factors can change the way our genes work for generations far into the future, without damaging the DNA. Professor Skinner is what’s called an epigeneticist and he joins me from Pullman, Washington. Welcome to Living on Earth.

SKINNER: Thank you very much.

GELLERMAN: So, Professor, I looked it up and ‘epi’ is Greek for ‘on or around’ and genetics means ‘source or origins.’ So epigenetics – around the source, yeah?

SKINNER: Correct. So epigenetics would be things around DNA that regulate DNA activity but are independent of DNA sequence, thus, epigenetic.

GELLERMAN: So, something’s gumming up the switch, it’s not destroying the DNA.

SKINNER: Correct, correct. And so basically, sometimes it’s the structure of the DNA, how tightly it’s coiled, or loosened up, that can actually change what genes are turned on and off. And the thing that we study the most is the chemical modification of the DNA, called methylation. A small chemical gets put on the DNA, and that can also regulate what genes are turned on and off. All of this can be influenced by the environment, has nothing to do with changing the DNA sequence.

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GELLERMAN: Is there any population evidence to suggest, historically, that we’ve detected this happening?

SKINNER: So, almost every region of the world has different disease frequencies. So, for example, in Japan they have a very high rate of a stomach disease, and a very low rate of a prostate disease. In North America, we have a very low rate of stomach disease, but a very high rate of prostate disease. If you take someone early in life from Japan and put them in the United States, they will develop generally the North American disease frequency and have prostate disease and low levels of stomach disease. This suggests an environmental impact on disease. And so there’s a lot of epidemiology experiments like that which support that kind of concept.

GELERMAN: So give me an example of something that my mom might have been exposed to that wouldn’t have caused a mutation in me, but would have affected my genetic expression, if you will.

SKINNER: First of all, the most logical one is nutrition. There’s lots of nutritional elements that can regulate programming of the embryo and different tissues. In addition, in our society today, most people are exposed to a wide variety of environmental compounds. Whether it be the bisphenol phthalates (sp?) from the plastics, whether it be agricultural compounds like the fungicide that we used called Encloselin, most people are exposed to these types of compounds on a pretty routine basis. And so these compounds have the ability to alter the epigenetics as well.

GELELRMAN: So we should really be looking at pregnant women.

SKINNER: Pregnant women are definitely the most sensitive population for influencing the fetus’ adult onset of disease. So, yes, these early life events causing later life disease is something we need to think about more, in terms of medicine. What you are is to a large degree determined what your mother did during pregnancy.

GELLERMAN: So are there a lot of epigenticists around? I’ve gotta admit that I’d never heard of it before.

SKINNER: It is a growing field. And I think it does address a lot of our unanswered questions using genetics. For established scientists that have grown up and been trained in genetics, it is a difficult shift in their thinking to consider that there may be something else. And so I think it’s going to be more the younger generation coming in that pushes the epigenetic area.

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The entire transcript, links to the podcast, and related links can all be found here.

Learn more at Dr. Skinner’s website.

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