Family living conditions in childhood are associated with significant effects in DNA that persist well into middle age, according to new research.
The research team — from McGill University in Montreal, the University of British Columbia in Vancouver, and the University College London (UCL) Institute of Child Health in London — looked for gene methylation associated with social and economic factors in early life. They found differences between those brought up in families with very high and very low standards of living.
More than twice as many differences were associated with the effects of early upbringing — from wealth to housing conditions to the occupations of parents — than were associated with the current socioeconomic conditions in adulthood. Researchers say they found 1,252 differences from early upbringing, compared to 545 for current conditions.
The findings could help explain why the health disadvantages associated with low socioeconomic conditions can remain for life, despite later improvements in living conditions, according to the researchers.
The study set out to explore the way early conditions in a child’s life might become “biologically embedded” and continue to influence health, for better or worse, throughout life. The scientists looked at DNA methylation, an external gene modification that is linked to lasting changes in gene activity, which can lead to potential health risks.
Researchers focused on 40 men who are part of the British Birth Cohort Study, which has followed more than 10,000 people born in March 1958 from birth to adulthood. The researchers studied DNA from blood samples taken when the participants were 45 years old.
Researchers chose people who experienced either very high or very low standards of living as children or adults. Their analysis measured DNA methylation differences between socioeconomic groups at the control regions of over 20,000 genes.
“This is the first time we’ve been able to make the link between the economics of early life and the biochemistry of DNA,” says Moshe Szyf, Ph.D., McGill professor of pharmacology.
“If we think of the genome as sentences, your DNA — or letters — are what is inherited from your father and mother,” he continued. “The DNA methylation is like the punctuation marks that determine how the letters should be combined into sentences and paragraphs that are read differently in the different organs of the body — the heart, the brain, and so on. What we’ve learned is that these punctuation marks are attentive to signals that come from the environment, and that they take cues from living conditions in childhood. Essentially, they act as a mechanism, we believe, for adapting the DNA to the fast-changing world.”
“We found a surprising amount of variation in DNA methylation — over 6,000 gene control regions showed clear differences between the 40 research participants,” added author Dr. Marcus Pembrey, emeritus professor at UCL Institute of Child Health. “Within this widespread variation, there was a distinct DNA methylation profile associated with high living standards in both childhood and as an adult. Even more surprising, given the DNA was obtained at 45 years, methylation levels for 1,252 gene promoters were associated with childhood living conditions compared to 545 promoters for living conditions in adulthood.”
The methylation profiles associated with childhood family living conditions were clustered in large stretches of DNA, which suggests that a well-defined pattern is linked to early socioeconomic environment, researchers add.
“The adult diseases already known to be associated with early life disadvantage include coronary heart disease, type 2 diabetes and respiratory disorders,” said author Chris Power, professor of epidemiology and public health at the UCL Institute of Child Health. “It is hoped that future research will define which network of genes showing methylation differences are in turn associated with particular diseases.”
“The current research represents just a beginning because it cannot tell us precisely when in early life these epigenetic patterns arose or what the long-term health effects will be,” he added. “This knowledge will be needed before useful interventions can be considered, but that must be the long-term aim.”
Source: McGill University