The human genome was fully mapped in the year 2000, a feat thought to be one of the most important medical science breakthroughs in history. As it turned out, there were only 25,000 genes, and the research did not yield the medical advances anticipated. In 2008, the National Institutes of Health (NIH) began to fund a different genetic initiative; one that sought to understand the epigenome.
The epigenome is described as the expression of the genome. Literally, epigenome means “above the genome.” Epigenetics is the study of changes in gene activity that do not involve changes to genetic code. One example of epigenetics is the addition or subtraction of small molecules called methyl or acetyl groups, which attach/detach to certain genes in processes known as methylation or acetylation. In methylation of the genome some genes are silenced, and others are turned on. Methylation determines how genes will be expressed, and it is the expression of genes that has an effect on our health. Think of your genome like a piano, and methylation like the pianist’s fingers, playing in tune to your health—or not.
Scientists have long known that epigenetics existed, because it explains how certain cells have the potential to develop into different cell types, depending on what is needed at the time. But what scientists didn’t know then that they know now, is epigenetics plays a major role in our health, and the health of our children. Lifestyle factors, like what we eat, what we are exposed to, and how we live, can affect our gene expression, and even the gene expression of our children for at least four generations.
Randy Jirtle PhD, a radiation biologist at Duke University, was among the first to experiment with DNA methylation in ways that gained much attention. His team conducted an experiment in pregnant mice that found methylation of a particular gene, the agouti gene, by administration of a diet rich in the B vitamins folic acid and B12 (both critically involved in methylation), resulted in offspring that were lean compared to obese offspring of pregnant mice not fed the diet.1,2
Dr. Jirtle stated, “The epigenome is most sensitive to perturbations in programming during the embryonic and the perinatal stages of development,”3 a statement highlighting the importance of healthy lifestyle of the mother before and during pregnancy and breast feeding, and of the children as they grow.
Puberty is another period when the epigenome is sensitive, especially in boys in whom sperm are beginning to develop (as opposed to in girls who carry eggs from birth). Toxin exposure plays a big role in epigenetics. Very early cigarette smoking in boys before age 11 has been found to later increase obesity in the sons of those men, illustrating the effects of the epigenome on the next generation.4
The message of epigenetic research is that we have more control over our genome, and thus, our health, than we once thought. Even small lifestyle changes can positively affect the expression of our genes in a way that results in positive health effects, in ourselves, in our children, and in our children’s children out several generations.
- R.A. Waterland and R.J. Jirtle, “Transposable elements: targets for early nutritional effects on epigenetic gene regulation.” Mol Cell Biol. 2003 August; 23(15): 5293–5300.
- R.J. Jirtle and M.K. Skinner, Environmental epigenomics and disease susceptibility.” Nat Rev Genet. 2007 Apr;8(4):253-62.
- B.M. Kuehn, “Randy L. Jirtle, PhD: Epigenetics a window on gene dysregulation, disease.” JAMA. 2008;299(11):1249-1250.
- M.E. Pembry, et al., “Sex-specific, male-line transgenerational responses in humans.” Eur J Hum Genet. 2006 Feb;14(2):159-66.