Our genome changes over lifetime, Johns Hopkins experts say

June 25, 2008

May explain many 'late-onset' diseases
Researchers at Johns Hopkins have found that epigenetic marks on DNA-chemical marks other than the DNA sequence-do indeed change over a person's lifetime, and that the degree of change is similar among family members. Reporting in the June 25 issue of the Journal of the American Medical Association, the team suggests that overall genome health is heritable and that epigenetic changes occurring over one's lifetime may explain why disease susceptibility increases with age.

"We're beginning to see that epigenetics stands at the center of modern medicine because epigenetic changes, unlike DNA sequence which is the same in every cell, can occur as a result of dietary and other environmental exposure," says Andrew P. Feinberg, M.D., M.P.H, a professor of molecular biology and genetics and director of the Epigenetics Center at the Johns Hopkins School of Medicine. "Epigenetics might very well play a role in diseases like diabetes, autism and cancer."

If epigenetics does contribute to such diseases through interaction with environment or aging, says Feinberg, a person's epigenetic marks would change over time. So his team embarked on an international collaboration to see if that was true. They focused on methylation-one particular type of epigenetic mark, where chemical methyl groups are attached to DNA.

"Inappropriate methylation levels can contribute to disease-too much might turn necessary genes off, too little might turn genes on at the wrong time or in the wrong cell," says Vilmundur Gudnason, MD, PhD, professor of cardiovascular genetics at the University of Iceland director of the Icelandic Heart Association's Heart Preventive Clinic and Research Institute. "Methylation levels can vary subtly from one person to the next, so the best way to get a handle on significant changes is to study the same individuals over time."

The researchers used DNA samples collected from people involved in the AGES Reykjavik Study (formerly the Reykjavik Heart Study). Within the study, about 600 people provided DNA samples in 1991, and again between 2002 and 2005. Of these, the research team measured the total amount of DNA methylation in each of 111 samples and compared total methylation from DNA collected in 2002 to 2005 to that person's DNA collected in 1991.

They found that in almost one-third of individuals, methylation changed over that 11-year span, but not all in the same direction. Some individuals gained total methylation in their DNA, while others lost. "What we saw was a detectable change over time, which showed us proof of the principle that an individual's epigenetics does change with age," says M. Daniele Fallin, Ph.D., an associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health. "What we still didn't know was why or how, but we thought 'maybe this, too, is something that's heritable' and could explain why certain families are more susceptible to certain diseases."

The team then measured total methylation changes in a different set of DNA samples collected from Utah residents of northern and western European descent. These DNA samples were collected over a 16-year span from 126 individuals from two- and three-generation families.

Similar to the Icelandic population, the Utah family members also showed varied methylation changes over time. But they found that family members tended to have the same kind of change-if one individual lost methylation over time, they saw similar loss in other family members.

"We still haven't concretely figured out what this means for health and disease, but as an epidemiologist, I think this is very interesting, since epigenetic changes could be an important link between environment, aging and genetic risk for disease," Fallin says.

Source: Johns Hopkins Medical Institutions

Explore further: Aging tests yield varying results

Related Stories

Aging tests yield varying results

November 15, 2017
Whether it's an on-line quiz, a $300 chromosome test or an $800 blood panel, a lot of people seem to be interested in whether they're aging faster or slower than their chronological age would suggest.

New therapy lessens impact of mistreatment at a young age

November 17, 2017
Everyone has challenges of one kind or another. But research shows that mistreatment at an early age can have long-lasting and life-altering repercussions that could be passed to future generations.

Mysterious DNA modification seen in stress response

October 24, 2017
With advances in genomics, scientists are discovering additional components of the DNA alphabet in animals. Do these unusual chemical modifications of DNA have a special meaning, or are they just signs that cellular machines ...

Blood-based epigenetic research may hold clues to autism biology, study suggests

October 24, 2017
Using data from blood and brain tissue, a team led by researchers at Johns Hopkins Bloomberg School of Public Health found that they could gain insights into mechanisms that might help explain autism by analyzing the interplay ...

Scientists use supercomputer to search for "memory molecules"

October 23, 2017
Until now, searching for genes related to memory capacity has been comparable to seeking out the proverbial "needle in a haystack." Scientists at the University of Basel made use of the CSCS supercomputer Piz Daint to discover ...

Epigenetic editing reveals surprising insights into early breast cancer development

November 13, 2017
Changing the epigenetic code of a single gene is enough to cause a healthy breast cell to begin a chain reaction and become abnormal, according to research by Queen Mary University of London (QMUL).

Recommended for you

New approach to studying chromosomes' centers may reveal link to Down syndrome and more

November 20, 2017
Some scientists call it the "final frontier" of our DNA—even though it lies at the center of every X-shaped chromosome in nearly every one of our cells.

Genome editing enhances T-cells for cancer immunotherapy

November 20, 2017
Researchers at Cardiff University have found a way to boost the cancer-destroying ability of the immune system's T-cells, offering new hope in the fight against a wide range of cancers.

A math concept from the engineering world points to a way of making massive transcriptome studies more efficient

November 17, 2017
To most people, data compression refers to shrinking existing data—say from a song or picture's raw digital recording—by removing some data, but not so much as to render it unrecognizable (think MP3 or JPEG files). Now, ...

Genetic mutation in extended Amish family in Indiana protects against aging and increases longevity (Update)

November 15, 2017
The first genetic mutation that appears to protect against multiple aspects of biological aging in humans has been discovered in an extended family of Old Order Amish living in the vicinity of Berne, Indiana, report Northwestern ...

US scientists try first gene editing in the body

November 15, 2017
Scientists for the first time have tried editing a gene inside the body in a bold attempt to permanently change a person's DNA to try to cure a disease.

Genetic variant prompts cells to store fat, fueling obesity

November 13, 2017
Obesity is often attributed to a simple equation: People are eating too much and exercising too little. But evidence is growing that at least some of the weight gain that plagues modern humans is predetermined. New research ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.