Exploring the Intersection of Genes and the Environment: How Racial Disparities Shape Health Outcomes

By: Aneri Tanna

Native American, Black and African American, and Hispanic individuals have all faced a higher rate of COVID-19 cases, hospitalizations, and deaths across the United States. These minority populations have borne a disproportionate burden of the pandemic due to social determinants of health (SDH). SDH are defined as conditions of the environments in which people are born, live, learn, work, play, worship, and age that affect a wide range of health, functioning, and quality-of-life outcomes and risks. The ecological model organizes the ways in which people’s interactions with their physical and sociocultural environments influence their health into 4 levels: individual, interpersonal, community, and structural factors. 

The levels of influence are individual factors (such as biology and personal history), interpersonal factors (such as close relationships including peers, partners, and family members), community factors (such as community norms and places of gathering including schools and workplaces), and structural factors (such as socio-cultural norms, policies, and access to health). 

Factors that play a significant role in affecting minority populations’ vulnerability to Covid can include pre-existing health conditions, poverty, physical environment, availability of healthcare, employment, access to health information, health insurance policy, etc. 

These social determinants of health can indirectly influence the health outcomes of people of color through influencing individuals’ health-seeking behaviors and shaping access to healthcare, but can also directly influence health outcomes through altering individuals’ biology. Epigenetics is the study of how behaviors and environment can cause heritable changes that affect the way genes are expressed without changing an individual’s genes (Centers for Disease Control and Prevention, 2020). An emerging field of study is exploring how racism plays a role in inducing epigenetic changes. This research explains another mechanism through which racial health inequities are produced. While there is not a biological basis for race, there appear to be tangible biological consequences of race as a social construct.

Existing literature has identified a number of ways in which gene expression—often epigenetically altered in response to external stressors such as racial stress—may explain some of these disparities across races and ethnicities (Olden, Olden, & Lin, 2015; Smith et al., 2017; Thames et al., 2019). For example, in African American individuals, DNA methylation—an epigenetic change typically resulting in gene silencing—has been linked to chronic pain, a greater likelihood of preterm birth, elevated blood pressure, and a higher incidence of cardiovascular disease among other conditions (Aroke et al., 2018; Barcelona de Mendoza et al., 2016; Brown et al., 2019; Kuzawa & Sweet, 2009; Barcelona de Mendoza et al., 2017). 

The attachment of an extra methyl group (methylation) within the promoter region of a gene typically impedes expression of the gene (Berger, 2007). Such epigenetic modifications can be incredibly long-lasting. Research has shown that even maternal or childhood stress stemming from racial and/or socioeconomic inequality can be associated with DNA methylation in adulthood (Kuzawa & Sweet, 2009; Miller et al., 2009; Borghol et al., 2011). 

Similar research on DNA methylation in Latina mothers has also demonstrated links between discrimination and stress-realted disorders (Santos et al., 2018). Additionally, a few other epigenetic mechanisms apart from DNA methylation—such as telomere shortening, histone protein modification, and RNA interference—have been studied as possible contributors to racial health disparities (Kuzawa & Sweet, 2009; Chae et al., 2020). The growing body of epigenetic research highlights the importance of considering racial inequity’s chronic and transgenerational biological consequences in addition to its creation of structural barriers to healthcare access.

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