Epigenetics is the study of how the external environment and your behavior cannot change your DNA sequence, but they can affect the way your genes work. The word "Epigenetic" means 'in addition to' or 'on top of' traditional genetic basis. Genetic changes are unchangeable, whereas epigenetic changes are reversible, and they do not change DNA sequence but instead focus on how DNA is regulated to read those changes and achieve them. Epigenetic changes can activate and deactivate genes.
Epigenetic changes are modifications that interfere with the transcription of particular genes. And the most common way of interference is that DNA or protein it's wrapped around, gets labeled with small chemical tags. The complete set of genes in a cell is called genome. And the set of all chemical tags that are attached to genome is called Epigenome.
Types of Epigenetic modification
DNA Methylation - It is a process where small methyl groups get added to the DNA molecule. Methylation can change the activity of some molecules or DNA segments without changing their sequence. When a methyl group is present in a gene, that gene gets deactivated, and no protein can be produced from it.
Histone Modification - Histone is a type of protein found in chromosomes. It helps give chromosomes their shape and helps control how the genes will work. The addition or removal of chemical groups can modify histones. Histone modifications control chromatin structure and gene transcription, which can impact important cellular phenotypes.
Epigenetics & Pregnancy
Epigenetic mechanisms in pregnancy are a dynamic phenomenon that responds both to maternal-fetal and environmental factors, which can influence and modify embryo-fetal development during the various gestational phases. Epigenetic changes begin in the prenatal period. All cells in the body have the same genes but look and act differently; as previously stated, it affects how the genes work rather than the DNA sequence. The function of a cell is determined by epigenetic (for example, will it become a heart cell, nerve cell etc).
Epigenetics also plays an important role in the development and physiology of the placenta. The placenta serves as both a protective and nutritional provider for the baby. So, when nutrition is limited, the placenta increases in order to absorb more nutrients from the mother's diet. It increases the capacity to transfer nutrients. So a big placenta can mean a big baby, but it can also have its own side effects or risks of chronic diseases.
The role of epigenetic mechanisms in translating early-life conditions into long-lasting gene expression changes underpinning stress-related behaviors.
Prenatal environmental exposures affect the child's health and development. When the fetus is exposed through the mother's environmental exposure, it affects the child's neurodevelopment and neurological behavior, particularly the risk of asthma, obesity, and metabolic disorders. Further, they may be increasing the risk of intermediate damage associated with cancer.
So, looking at all these factors, experts think epigenetics is a very important mechanism in mediating those effects and helping to link exposures to clinical outcomes, which can be useful in designing effective interventions.