Archives for posts with tag: genetics

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.

More.

From Environmental Health News:

Bisphenol A (BPA) can alter the way genes are read in male rats exposed to the chemical as newborns. The so-called epigenetic changes had lasting effects on reproductive hormone signals into adulthood that may partially explain reported effects of the chemical on male fertility.

The findings add to a growing body of research showing that BPA can impact the way genes are coded and then interpreted later in life during sexual maturity. Such changes have been documented in the brain, prostate and uterus.

The early-life exposures added chemical groups to two important genes on the DNA in the testes and increased the levels of enzymes that control these epigenetic additions. Due to the broader impact on these enzyme levels, newborn BPA exposure may affect more genes and levels of control than identified in the current study.

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From San Francisco Chronicle:

Environmental factors play a more important role in causing autism than previously assumed and, surprisingly, an even larger role than genetics, according to a new study out of UCSF and Stanford that could force a dramatic swing in the focus of research into the developmental disorder.

The study, published in Monday’s issue of the Archives of General Psychiatry, looked at 192 pairs of twins in California and, using a mathematical model, found that genetics account for about 38 percent of the risk of autism, and environmental factors account for about 62 percent.

Previous twin studies had suggested that autism was highly inheritable, with genetics accounting for roughly 90 percent of all cases worldwide. As such, much recent research into autism has focused on tracking down the genes and unlocking the complex genetic codes that are associated with autism.

“We’re not trying to say there isn’t a genetic component – quite the opposite. But for most individuals with autism spectrum disorder, it’s not simply a genetic cause,” said Neil Risch, director of the UCSF Institute for Human Genetics, who designed the study.

Autism doctors and patient advocates said the study, which will probably be followed up with similar studies of twins and other siblings, could have a significant impact on research into the disorder.

More.

From whenvironments:

An excerpt from the award-winning documentary, “Exposure: Environmental Links to Breast Cancer” focusing on the facts about mammography. Featuring Olivia Newton-John, Dr. Rosalie Bertell, Sharon Batt and Dr. Susan Love.

From All Things Considered (portions of a radio news story discussing a recent Nature article challenging the conventional wisdom about genetic inheritance):

We can’t change the genes we received from our parents. But our genes are controlled by a kind of instruction manual made up of billions of chemical markers on our DNA, and those instructions can be rewritten by our circumstances — for instance, by obesity. According to the new research, they can even be passed along to children.

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The Grammar Of DNA

[Andy] Feinberg thinks he knows how this may be happening. It’s an example of an “epigenetic” effect, which is his specialty.

This field — epigenetics — is getting a lot of attention these days. It refers to things in and around our DNA, such as billions of chemical markers that attach to it. Those markers are signals that turn genes on and off. They tell the genes of a liver cell to behave differently from genes in a blood cell, for instance.

The sequence of our DNA — the human genome — has been called the book of life. Feinberg has his own metaphor for the billions of added signals that he studies. If the genetic sequence is the words of the book, the epigenome is the grammar, he says. “It helps to tell what the genes are actually supposed to do, and puts them in context.”

Our genes don’t change, or if they do, it’s a rare and random event. But the grammar of the epigenome is changing all the time. It can also be disrupted by chemicals we eat or breathe.

Apparently it can also be disrupted by obesity, because Feinberg thinks those fat dad rats in Australia created sperm cells with a different pattern of epigenetic marks on their DNA; that’s how the effect showed up in their children.

Michael Skinner at Washington State University in Pullman says epigenetic effects are swinging the pendulum of scientific attention from the genetic code back toward the impact of environment.

“I think that we’re eventually going to have sort of a merger of this,” he says. “I think that we’re going to have an appreciation of the fact that there is an environmental influence on biology that probably through more epigenetic mechanisms. There’s also a baseline genetic element of biology. And the two combined will actually give us more information about how things work.”

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

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