Twins one month old.
Differences Between Twins at Birth Highlights Uterine Environment
Research has for the first time shown that the environment in the womb defines the newborn epigenetic profile - the chemical modifications to DNA we are born with - that could have implications for disease risk later in life
Your genes determine much about you, but environment can have a strong influence on your genes even before birth, with consequences that can last a lifetime.
The study is published online in Genome Research.
Epigenetic tagging of genes by a chemical modifier called DNA methylation, is known to affect gene activity, playing a role in normal development, aging, and also in diseases such as diabetes, heart disease, and cancer.
Studies conducted in animals have shown that environment shapes the epigenetic profile across the genome, called the epigenome, particularly in the womb. An understanding of how the intrauterine environment molds the human epigenome could provide critical information about disease risk to help manage health throughout life.
Twin pairs, both monozygotic (identical) and dizygotic (fraternal), are ideal for epigenetic study because they share the same mother but have their own umbilical cord and amniotic sac, and in the case of identical twins, also share the same genetic make-up. Previous studies have shown that methylation can vary significantly at a single gene across multiple tissues of identical twins, but it is important to know what the DNA methylation landscape looks like across the genome.
In this report, an international team of researchers has for the first time analyzed genome-scale DNA methylation profiles of umbilical cord tissue, cord blood, and placenta of newborn identical and fraternal twin pairs to estimate how genes, the shared environment that their mother provides and the potentially different intrauterine environments experienced by each twin contribute to the epigenome.
The group found that even in identical twins,
there are widespread differences in the
epigenetic profile of twins at birth.
"This must be due to events that happened to one twin and not the other," said Dr. Jeffrey Craig of the Murdoch Childrens Research Institute (MCRI) in Australia and a senior author of the report. Craig added that
Although twins share a womb,
the influence of specific tissues like
the placenta and umbilical cord can be different
for each fetus, and likely affects
the epigenetic profile.
Interestingly, the team found that methylated genes closely associated with birth weight in their cohort are genes known to play roles in growth, metabolism, and cardiovascular disease, lending further support to a known link between low birth weight and risk for diseases such as diabetes and heart disease.
The authors explained that their findings suggest the unique environmental experiences in the womb may have a more profound effect on epigenetic factors that influence health throughout life than previously thought. Furthermore, an understanding of the epigenetic profile at birth could be a particularly powerful tool for managing future health.
Dr. Richard Saffery of the MCRI and a co-senior author of the study: "This has potential to identify and track disease risk early in life, or even to modify risk through specific environmental or dietary interventions."
Scientists from the Murdoch Childrens Research Institute (Parkville, Australia), the University of Melbourne, Australia), the University of Queensland Diamantina Institute (Brisbane, Australia), the Queensland Institute of Medical Research (Brisbane, Australia), the Hjelt Institute at the University of Helsinki (Helsinki, Finland), the Emory University School of Medicine (Atlanta, GA), and the University of Wisconsin School of Medicine (Madison, WI) contributed to this study.
This work was supported by the Australian National Health and Medical Research Council, the Bonnie Babes Foundation, the Sigrid Juselius Foundation, the Academy of Finland, the Finnish Cultural Foundation, the Financial Markets Foundation for Children, and the Victorian Government's Operational Infrastructure Support Program.
About the article:
The manuscript will be published online ahead of print on Monday, July 16, 2012. Its full citation is as follows: Gordon L, Joo JE, Powell JE, Ollikainen M, Novakovic B, Li X, Andronikos R, Cruickshank MN, Conneely KN, Smith AK, Alisch RS, Morley R, Visscher PM, Craig JM, Saffery R. Neonatal DNA methylation profile in human twins is specified by a complex interplay between intrauterine environmental and genetic factors, subject to tissue-specific influence. Genome Res doi: 10.1101/gr.136598.111.
About Genome Research:
Launched in 1995, Genome Research(www.genome.org) is an international, continuously published, peer-reviewed journal that focuses on research that provides novel insights into the genome biology of all organisms, including advances in genomic medicine. Among the topics considered by the journal are genome structure and function, comparative genomics, molecular evolution, genome-scale quantitative and population genetics, proteomics, epigenomics, and systems biology. The journal also features exciting gene discoveries and reports of cutting-edge computational biology and high-throughput methodologies.
About Cold Spring Harbor Laboratory Press:
Cold Spring Harbor Laboratory is a private, nonprofit institution in New York that conducts research in cancer and other life sciences and has a variety of educational programs. Its Press, originating in 1933, is the largest of the Laboratory's five education divisions and is a publisher of books, journals, and electronic media for scientists, students, and the general public.
Genome Research issues press releases to highlight significant research studies that are published in the journal.
Original article: http://www.eurekalert.org/pub_releases/2012-07/cshl-dbh071112.php