1. Hertzmann and Boyce argue that “it is not genes or environment, nor is it genes and environment, but rather it is gene-by-environment interactions that influence developmental trajectories.” To what extent do you think that GxE interactions can contribute to major disparities along racial/ethnic, socioeconomic, or geographic dimensions? Please consider this both in general and in respect to your particular area of interest
I think gene-by-environment interactions play a major role in disparities along racial/ethnic, socioeconomic or geographic dimensions. In general, genes predisposing to worse health outcomes are distributed roughly equally in the society. However, people from disadvantaged racial/ethnic, socioeconomic or geographic background are exposed to an environment that promotes the expression of these genes, contributing to poor health outcomes. On the other hand, people from advantaged racial/ethnic, socioeconomic or geographic background are exposed to an environment that protects them against the expression of these harmful genes and therefore, they may have better health outcomes compared with the disadvantaged population, despite having a similar genetic background. In the field of nephrology, a good example of this is APOL1 gene that is prevalent in African Americans and predisposes them to develop kidney disease. In those who have this gene but have an advantaged background and therefore, have good access to health care and screening, predisposing factors to expression of this gene like hypertension will be detected and treated early so the chance of development of kidney disease decreases. However, in those with APOL1 gene who have a disadvantaged background, predisposing factors like hypertension would go undetected and uncontrolled and therefore, they will contribute to the worsening effect of this gene and resulting in development of kidney disease. The interaction between APOL1 genetic predisposition and environmental factors that contribute to the worsening effect of this gene has been considered as one of the reasons African Americans have a higher burden of kidney disease in the US.
2. Discuss implications of epigenetic mechanisms of disease for intergenerational effects on health disparities, as well as for interventions designed to address health disparities.
Epigenetic mechanisms of disease significantly impact the intergenerational effects on health disparities as well as the intervention designed to address these health disparities. Exposure to stressful environments during prenatal period or during childhood can result in permanent epigenetic changes which in turn can result in different expression of genes, ultimately resulting in worse health outcomes. For example, in the article by Barcelona de Mendoza, it was shown that there are significant epigenetic associations between disease-associated genes (e.g., schizophrenia, bipolar disorder, and asthma) and
perceived discrimination in African American women. These epigenetic changes can be transmitted to subsequent generations resulting in a vicious cycle of worsening intergenerational health disparities. One important aspect of the impact of epigenetic mechanisms of disease on intergenerational effects of health disparities is that the interventions designed to address health disparities may take generations to be show their full beneficial effects considering that many of these epigenetic changes happen in prenatal or early childhood periods. Therefore, these interventions should be started early in life and continued across generations.
3. Discuss how the findings in the Robinette paper relate to socioecological model we are using in this course – e.g. briefly describe how the different levels displayed in this model are related to each other in this paper.
In the paper by Robinette et al, it’s shown that people living in lower income neighborhood have higher allostatic load. Low income neighborhood in this study is a surrogate for the economic and social disparities and allostatic load is a measure posited to capture the cumulative effect of these stressors on wean and tear of the body. Several factors associated with living in low socioeconomic neighborhoods contribute to this increased allostatic load including higher rate of crime and violence which results in an unsafe environment that prevents residents of these neighborhoods from outdoor activities and social gatherings and therefore, result in higher levels of stress and isolation. Access to healthy food like fruits and vegetables in these neighborhoods could be hard and lack of job opportunities can result in worsening economic disparities and in result lower rate of access to medical care. All these factors associated with living in a low socioeconomic neighborhood can interact with each other and result in higher allostatic load and worse health outcomes. These results show the similar paradigm that was shown by our model: behavioral factors and medical care that patients receive which is in turn is influenced by working and living conditions of individual in context of economic and social disparities interacts with biologic and genetic factors and over time result in disparities in health outcomes.