aging environment disease methylation: Genome study yields clue

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Note the role for methylation

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Genome study yields clue

Hopkins researchers say there could be indication of link between age,

disease

By Bor | Sun Reporter

June 25, 2008

http://www.baltimoresun.com/technology/bal-te.genes25jun25,0,1038268.story

s Hopkins researchers who studied the genomes of people in Iceland

and Utah say they may have found a clue to why people are increasingly

prone to disease as they age.

The answer may not lie specifically in the person's genes, but in

chemical changes occurring around the genes that help determine which

are active and which are silent.

As a result, a person could become more prone to heart disease, cancer

and other diseases of aging because certain genes that used to function

no longer do so - or vice versa. Animal studies have shown that such

changes can be triggered by environmental forces such as diet.

" It could be that if you ate a lot of food with high levels of metals,

or if you smoked, you could have changes over time in the expression of

particular genes that cause you to be at risk for disease, " said M.

e Fallin, an associate professor of epidemiology at the s

Hopkins Bloomberg School of Public Health.

Dr. Feinberg, a professor of molecular biology and genetics at

the Hopkins medical school, said the report " opens up a whole new avenue

of study. " Feinberg was lead author of the study, which appears in

today's Journal of the American Medical Association.

Collaborating with scientists at the University of Iceland, the Hopkins

researchers studied two populations over time to see if they could

observe changes in the amount of " methylation " present in a person's genome.

The term refers to the attachment of methyl groups (molecules of carbon

and hydrogen) along the genetic sequence that makes up a person's DNA.

They trigger the activation of genes - helping to determine, for

instance, why skin cells are different from blood or heart cells despite

having identical DNA.

The degree of methylation is part of a person's epigenetics - aspects of

an individual's makeup that exist apart from the genes themselves.

The researchers tapped into continuing studies in Utah and Iceland, both

havens for genetic research because of homogeneous populations. The

researchers obtained DNA samples given over a decade apart by 111 people

in Iceland and 126 in Utah.

For each person, they measured the amount of methylation present at each

point in time - about a third of the subjects in Iceland and 30 percent

in Utah had substantial changes over the period.

In the Utah group, they also discovered that the tendency to undergo

epigenetic changes ran in families. In other words, if one person

experienced abnormal methylation over time, other members of the family

were likely to do so as well.

Feinberg noted that many diseases occurring early in life, such as

cystic fibrosis, are caused by the transmission of abnormal genes from

parent to child. But others that occur much later in life may be

influenced by the interactions of genes and the environment.

Environmental factors can increase the amount and the location of

methylation along the genome, influencing whether genes are functioning

or not. The changes can also occur randomly, as cells divide and

information gets lost or jumbled.

jonathan.bor@...

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