Epigenetics

Epigenetics refers to the heritable changes that impact gene expression without affecting the underlying DNA (deoxyribonucleic acid) sequence. Epigenetics can also be described as the study of chemical modifications affecting the activation or silencing of genes not caused by changes in the DNA sequence, the environmental factors playing a part in these chemical modifications, and the ways these modifications, or markers, are inherited.

Understanding Epigenetics

Epigenetics refers to the study of the way different chemical groups attach on or beside the DNA structure. These chemical groups do not change the underlying structure of the DNA, but they do impact the way affected genes are expressed. In other words, the epigenome—a chemical “tag” that attaches to DNA—can change and react, while DNA remains the same throughout life. Throughout one’s life, the epigenome reacts to aging, nutrition, the environment, and other events and aspects of human development, and this reaction can cause lasting physical changes.

Epigenetics is a multifaceted and developing field. The following fundamental concepts outline the general principles of epigenetics:

• Epigenetic changes are a normal part of human development: Epigenetics is the study of the mechanisms by which cells with the same DNA are uniquely expressed throughout human development. For example, epigenetic markers tell a brain cell to act like a brain cell and a skin cell to act like a skin cell, even though they essentially have the same DNA material.
• Epigenetic changes can be influenced by nutrition, the environment, and health: Environmental toxins or conditions can alter the ways genes are regulated. For example, malnourishment experienced in childhood may cause disease in later life, due to the silencing of certain genes. Even if a person eventually achieves a healthy lifestyle, these epigenetic changes may still have an effect.
• Major events can change the way genes are expressed: Studies have shown that children who experience trauma at a young age may be susceptible to biological changes that affect them later in life. For example, an 8-year-old child who is physically abused on a daily basis may experience epigenetic changes in response to the level of stress and trauma experienced. These changes may affect how that child responds to stress as an adult.
• Changes in gene expression can be inherited for generations: Parents’ experiences can be passed on to children in the form of chemical tags attached to the genetic code. For example, the damaging epigenetic changes that may occur in a parent who abuses alcohol can be passed on to a child.
• Epigenetic changes can be reversible: Many hope that the study of epigenetics will bring about potential cures for diseases like cancer, Alzheimer’s, and diabetes. For example, if researchers can determine which gene combinations impact which diseases, they may be able to reverse the silencing of these genes.

The study of epigenetics also provides insight into the nature vs. nurture debate. Twin studies help researchers understand how biology and environment each play a role in human development. Identical twins have identical genetic codes; therefore, when only one twin develops a disease, environmental factors are often explored, as epigenetic changes may have been activated by certain environmental events that only one twin experienced. Similarly, when both twins develop a disease, biological and genetic factors can be analyzed. In this manner, twin studies may be extremely useful in determining the causes and means for prevention of various diseases.

The History of Epigenetics

Epigenetics’ origin can be traced to the the mid-twentieth century work of scientists Conrad H. Waddington and Ernst Hadorn. While conducting research that focused on developmental biology and genetics, Waddington and Hadorn developed an early model for the field that is now called epigenetics. Though their work showed promise, it was rejected by the scientific community of the time, and development of the field was stalled. 

In the 1990s, scientific interest in genetic assimilation led Waddington to revisit his work. Since then, the field has evolved significantly, and research findings continue to highlight the connection between epigenetics and physical and mental health issues, in hopes that the connection will lead to developments in disease treatment and prevention.

Epigenetics and Mental Health

As a result of the link between epigenetics and disease prevention, the fields of epigenetics and mental health have a strong connection. Many studies have already identified epigenetic mechanisms that might lead to the development of various mental health issues. Research indicates that epigenetic changes may be linked to the development of the following conditions:

• Schizophrenia
• Intellectual disabilities
• Autism
• Posttraumatic stress
• Alzheimer’s disease
• Mood-related issues
• Alcohol abuse
• Depression
• Anxiety

In addition to these findings, studies have shown that the children of adults who experienced childhood abuse or neglect may inherit the epigenetic modifications that resulted from the abuse. Therefore, both the mental health of the parents who experienced the abuse, and that of any children they might have may be affected. Traumatic experiences often leave molecular “scars” that attach to a person’s DNA, impacting development and mental health throughout life.

These findings may be troubling to some, but they imply the importance of stress prevention as a factor in avoiding negative epigenetic effects. Furthermore, researchers may be able to use these findings in the future for the prevention and cure of certain mental health issues.

References

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10. Kirkpatrick, B. (2014, June 18). Dad’s drinking could epigenetically affect son’s sensitivity and preference for alcohol. In What is Epigenetics. Retrieved from http://www.whatisepigenetics.com/dads-drinking-could-epigenetically-affect-sons-sensitivity-and-preference-for-alcohol.
11. Kirkpatrick, B. (2014, September 9). Epigenetic mechanism proposes potential markers for depression and anxiety. In What is Epigenetics. Retrieved from http://www.whatisepigenetics.com/epigenetic-mechanism-proposes-potential-markers-for-depression-and-anxiety.
12. Kirkpatrick, B. (2014, April 23). A Father’s stress felt for generations. In What is Epigenetics. Retrieved from http://www.whatisepigenetics.com/a-fathers-stress-felt-for-generations.
13. Robinson, S. (2014, October 8). A Brief history of epigenetics: c.h. waddington. In The Nexus of Epigenetics. Retrieved from https://epigeneticsguy.wordpress.com/2014/10/08/a-brief-history-of-epigenetics-c-h-waddington.

Last Updated: 01-29-2016