Epigenetics: Where Environment, Society and Genetics Meet

Abstract

Understanding how environment, social factors and genetics combine to affect patterns of health is an urgent priority. Social factors that affect health patterns include race and socioeconomic status (SES), while biological factors include sex, genetics and epigenetics. The consequence of biology and environment can be observed in life expectancy data. At 25 years old, life expectancy for white men is 4.4 years greater than for African–American men. Females follow a similar pattern. Income also affects life expectancy with high income earners outliving their low income counterparts, and white males and females outliving African–American males and females by 2–4 years at every income level [1]. Environment also affects perinatal mortality. US-born African–American women experience greater rates of perinatal mortality than their foreign-born counterparts [2]. Similar patterns can be observed with multiple health conditions, including cancer, depression, diabetes and heart disease highlighting the importance of this issue [1]. What is less clear is the mechanism by which these disparities are caused. One way in which biology and environment can both leave their fingerprint is through epigenetic changes. Epigenetics refers to the regulation of gene expression through modifications to DNA or DNA-associated proteins. Epigenetic regulation includes histone modifications, DNA methylation and nonprotein coding RNA. DNA methylation has been a particular focus of environment-mediated changes in health. Methylation changes have been associated with environmental chemical exposure [3], race, gender [4] and income level [5]. However, epigenetic gene regulation is bigger than methylation alone. Human and animal studies have begun to investigate environmental effects on epigenetics. While these publications are increasing, some factors need to be considered, these include tissue specificity, epigenetic specificity and transgenerational studies.