The Intergenerational Impact of Genetic and Psychological Factors on Blood Pressure (InterGEN) Study: Design and Methods for Complex DNA Analysis

Epigenome-Wide Association Study of Depressive Symptoms in Black Women in the InterGEN Study

(1) The prevalence of depression is two times higher in women than men. Black women have an increased risk of depression due to stressors such as low socioeconomic status and perceived discrimination. Depression is likely influenced by both genetic and environmental factors. Psychosocial stressors can influence DNA methylation (DNAm), leading to changes in gene expression and ultimately, depression. The objective of this study was to examine associations between DNAm and depressive symptoms in Black women. (2) This study was a secondary analysis of data from the Intergenerational Impact of Genetic and Psychological Factors on Blood Pressure (InterGEN) Study. Perceived discrimination was assessed using Krieger's Experiences of Discrimination and Waelde's Race-Related Events Scale, and participants were screened for depressive symptoms with the Beck Depression Inventory. Raw data from saliva samples were analyzed using the Illumina Infinium Epic (850 K) BeadChip and then preprocessed in RStudio. (3) Differential methylation analysis identified DNAm sites and regions associated with depressive symptoms. Six DNAm sites had a q-value less than 0.05. Additionally, of the 25 regions identified, 12 were associated with neurological diseases or disorders. (4) These findings suggest that there is a neurological component to depression, which should be considered during treatment.

The race-based stress reduction intervention (RiSE) study on African American women in NYC and Chicago: Design and methods for complex genomic analysis

RiSE study aims to evaluate a race-based stress-reduction intervention as an effective strategy to improve coping and decrease stress-related symptoms, inflammatory burden, and modify DNA methylation of stress response-related genes in older AA women. This article will describe genomic analytic methods to be utilized in this longitudinal, randomized clinical trial of older adult AA women in Chicago and NYC that examines the effect of the RiSE intervention on DNAm pre- and post-intervention, and its overall influence on inflammatory burden. Salivary DNAm will be measured at baseline and 6 months following the intervention, using the Oragene-DNA kit. Measures of perceived stress, depressive symptoms, fatigue, sleep, inflammatory burden, and coping strategies will be assessed at 4 time points including at baseline, 4 weeks, 8 weeks, and 6 months. Genomic data analysis will include the use of pre-processed and quality-controlled methylation data expressed as beta (β) values. Association analyses will be performed to detect differentially methylated sites on the targeted candidate genes between the intervention and non-intervention groups using the Δβ (changes in methylation) with adjustment for age, health behaviors, early life adversity, hybridization batch, and top principal components of the probes as covariates. To account for multiple testing, we will use FDR adjustment with a corrected p-value of <0.05 regarded as statistically significant. To assess the relationship between inflammatory burden and Δβ among the study samples, we will repeat association analyses with the inclusion of individual inflammation protein measures. ANCOVA will be used because it is more statistically powerful to detect differences.

The Cumulative Influence of Perceived Discrimination, Stress, and Coping Responses on Symptoms of Depression Among Young African American Mothers

BACKGROUND

African American women have an elevated risk for experiencing depressive symptoms, and discrimination, stress, and coping contribute to symptoms of depression.

AIMS

We aimed to examine the associations between discrimination, stress, and coping on symptoms of depression among young African American mothers.

METHODS

In this retrospective study, we utilized a hierarchical linear regression to explore the effects of perceived racial discrimination, stress, and general and discrimination-related coping responses on depressive symptoms in a sample of African American mothers (N = 250). The data were drawn from the Intergenerational Impact of Genetic and Psychological Factors on Blood Pressure study (InterGEN), a study conducted between 2014 and 2019 and based in Connecticut.

RESULTS

After accounting for maternal age, level of education, and income, greater perceived racial discrimination (p = .03), higher levels of stress (p < .001), greater engagement in avoidance coping (p < .001), and use of passive coping responses to discrimination (p = .04) were uniquely associated with increased depressive symptoms. Other forms of coping, specifically, problem-solving and support seeking, did not appear to influence depressive symptoms in this sample.

CONCLUSION

The findings highlight the negative impact of discrimination, heightened stress, and maladaptive coping on the emotional health of young African American mothers.

A roadmap for social determinants of health and biological nursing research in the National Institute of Nursing Research 2022-2026 Strategic Plan: Optimizing health and advancing health equity using antiracist framing

BACKGROUND

Health equity is essential for improving the well-being of all individuals and groups, and research remains a critical element for understanding barriers to health equity. While considering how to best support research that acknowledges current health challenges, it is crucial to understand the role of social justice frameworks within health equity research and the contributions of minoritized researchers. Additionally, there should be an increased understanding of the influence of social determinants of health on biological mechanisms.

PURPOSE

Biological health equity research seeks to understand and address health disparities among historically excluded populations.

DISCUSSION

While there are examples of studies in this area led by minoritized researchers, some individuals and groups remain understudied due to underfunding. Research within minoritized populations must be prioritized to authentically achieve health equity. Furthermore, there should be increased funding from National Institutes of Health to support minoritized researchers working in this area.

Latent Class Analysis of Depressive Symptom Phenotypes Among Black/African American Mothers

BACKGROUND

Depression is a growing global problem with significant individual and societal costs. Despite their consequences, depressive symptoms are poorly recognized and undertreated because wide variation in symptom presentation limits clinical identification-particularly among African American (AA) women-an understudied population at an increased risk of health inequity.

OBJECTIVES

The aims of this study were to explore depressive symptom phenotypes among AA women and examine associations with epigenetic, cardiometabolic, and psychosocial factors.

METHODS

This cross-sectional, retrospective analysis included self-reported Black/AA mothers from the Intergenerational Impact of Genetic and Psychological Factors on Blood Pressure study (data collected in 2015-2020). Clinical phenotypes were identified using latent class analysis. Bivariate logistic regression examined epigenetic age, cardiometabolic traits (i.e., body mass index ≥ 30 kg/m 2 , hypertension, or diabetes), and psychosocial variables as predictors of class membership.

RESULTS

All participants were Black/AA and predominantly non-Hispanic. Over half of the sample had one or more cardiometabolic traits. Two latent classes were identified (low vs. moderate depressive symptoms). Somatic and self-critical symptoms characterized the moderate symptom class. Higher stress overload scores significantly predicted moderate-symptom class membership.

DISCUSSION

In this sample of AA women with increased cardiometabolic burden, increased stress was associated with depressive symptoms that standard screening tools may not capture. Research examining the effect of specific stressors and the efficacy of tools to identify at-risk AA women are urgently needed to address disparities and mental health burdens.

Epigenome-wide association study of BMI in Black populations from InterGEN and GENOA

OBJECTIVE

Obesity is a significant public health concern across the globe. Research investigating epigenetic mechanisms related to obesity and obesity-associated conditions has identified differences that may contribute to cellular dysregulation that accelerates the development of disease. However, few studies include Black women, who experience the highest incidence of obesity and early onset of cardiometabolic disorders.

METHODS

The association of BMI with epigenome-wide DNA methylation (DNAm) was examined using the 850K Illumina EPIC BeadChip in two Black populations (Intergenerational Impact of Genetic and Psychological Factors on Blood Pressure [InterGEN], n = 239; and The Genetic Epidemiology Network of Arteriopathy [GENOA] study, n = 961) using linear mixed-effects regression models adjusted for batch effects, cell type heterogeneity, population stratification, and confounding factors.

RESULTS

Cross-sectional analysis of the InterGEN discovery cohort identified 28 DNAm sites significantly associated with BMI, 24 of which had not been previously reported. Of these, 17 were replicated using the GENOA study. In addition, a meta-analysis, including both the InterGEN and GENOA cohorts, identified 658 DNAm sites associated with BMI with false discovery rate < 0.05. In a meta-analysis of Black women, we identified 628 DNAm sites significantly associated with BMI. Using a more stringent significance threshold of Bonferroni-corrected p value 0.05, 65 and 61 DNAm sites associated with BMI were identified from the combined sex and female-only meta-analyses, respectively.

CONCLUSIONS

This study suggests that BMI is associated with differences in DNAm among women that can be identified with DNA extracted from salivary (discovery) and peripheral blood (replication) samples among Black populations across two cohorts.

The Interaction of Trauma Exposure and DNA Methylation on Blood Pressure Among Black Women in the InterGEN Study

Objective

Despite evidence that trauma exposure is linked to higher risk of hypertension, epigenetic mechanisms (such as DNA methylation) by which trauma potentially influences hypertension risk among Black adults remain understudied.

Methods

Data from a longitudinal study of Black mothers were used to test the hypothesis that direct childhood trauma (ie, personal exposure) and vicarious trauma (ie, childhood trauma experienced by their children) would interact with DNA methylation to increase blood pressure (BP). Separate linear mixed effects models were fitted at each CpG site with the DNA methylation beta-value and direct and vicarious trauma as predictors and systolic and diastolic BP modeled as dependent variables adjusted for age, cigarette smoking, and body mass index. Interaction terms between DNA methylation beta-values with direct and vicarious trauma were added.

Results

The sample included 244 Black mothers with a mean age of 31.2 years (SD = ±5.8). Approximately 45% of participants reported at least one form of direct childhood trauma and 49% reported at least one form of vicarious trauma. Epigenome-wide interaction analyses found that no CpG sites passed the epigenome-wide significance level indicating the interaction between direct or vicarious trauma with DNAm did not influence systolic or diastolic BP.

Conclusions

This is one of the first studies to simultaneously examine whether direct or vicarious exposure to trauma interact with DNAm to influence BP. Although findings were null, this study highlights directions for future research that investigates epigenetic mechanisms that may link trauma exposure with hypertension risk in Black women.

Stress Overload and DNA Methylation in African American Women in the Intergenerational Impact of Genetic and Psychological Factors on Blood Pressure Study

Introduction:

Experiencing psychosocial stress is associated with poor health outcomes such as hypertension and obesity, which are risk factors for developing cardiovascular disease. African American women experience disproportionate risk for cardiovascular disease including exposure to high levels of psychosocial stress. We hypothesized that psychosocial stress, such as perceived stress overload, may influence epigenetic marks, specifically DNA methylation (DNAm), that contribute to increased risk for cardiovascular disease in African American women.

Methods:

We conducted an epigenome-wide study evaluating the relationship of psychosocial stress and DNAm among African American mothers from the Intergenerational Impact of Genetic and Psychological Factors on Blood Pressure (InterGEN) cohort. Linear mixed effects models were used to explore the epigenome-wide associations with the Stress Overload Scale (SOS), which examines self-reported past-week stress, event load and personal vulnerability.

Results:

In total, n = 228 participants were included in our analysis. After adjusting for known epigenetic confounders, we did not identify any DNAm sites associated with maternal report of stress measured by SOS after controlling for multiple comparisons. Several of the top differentially methylated CpG sites related to SOS score (P < 1 × 10⁻⁵), mapped to genes of unknown significance for hypertension or heart disease, namely, PXDNL and C22orf42.

Conclusions:

This study provides foundational knowledge for future studies examining epigenetic associations with stress and other psychosocial measures in African Americans, a key area for growth in epigenetics. Future studies including larger sample sizes and replication data are warranted.

Experiences of Trauma and DNA Methylation Profiles among African American Mothers and Children

Potentially traumatic experiences have been associated with chronic diseases. Epigenetic mechanisms, including DNA methylation (DNAm), have been proposed as an explanation for this association. We examined the association of experiences of trauma with epigenome-wide DNAm among African American mothers (n = 236) and their children aged 3–5 years (n = 232; N = 500), using the Life Events Checklist-5 (LEC) and Traumatic Events Screening Inventory—Parent Report Revised (TESI-PRR). We identified no DNAm sites significantly associated with potentially traumatic experience scores in mothers. One CpG site on the ENOX1 gene was methylome-wide-significant in children (FDR-corrected q-value = 0.05) from the TESI-PRR. This protein-coding gene is associated with mental illness, including unipolar depression, bipolar, and schizophrenia. Future research should further examine the associations between childhood trauma, DNAm, and health outcomes among this understudied and high-risk group. Findings from such longitudinal research may inform clinical and translational approaches to prevent adverse health outcomes associated with epigenetic changes.

Associations Between DNA Methylation Age Acceleration, Depressive Symptoms, and Cardiometabolic Traits in African American Mothers From the InterGEN Study

Background

African American women (AAW) have a high risk of both cardiometabolic (CM) illness and depressive symptoms. Depressive symptoms co-occur in individuals with CM illness at higher rates than the general population, and accelerated aging may explain this. In this secondary analysis, we examined associations between age acceleration; depressive symptoms; and CM traits (hypertension, diabetes mellitus [DM], and obesity) in a cohort of AAW.

Methods

Genomic and clinical data from the InterGEN cohort (n = 227) were used. Age acceleration was based on the Horvath method of DNA methylation (DNAm) age estimation. Accordingly, DNAm age acceleration (DNAm AA) was defined as the residuals from a linear regression of DNAm age on chronological age. Spearman's correlations, linear and logistic regression examined associations between DNAm AA, depressive symptoms, and CM traits.

Results

DNAm AA did not associate with total depressive symptom scores. DNAm AA correlated with specific symptoms including self-disgust/self-hate (-0.13, 95% CI -0.26, -0.01); difficulty with making decisions (-0.15, 95% CI -0.28, -0.02); and worry over physical health (0.15, 95% CI 0.02, 0.28), but were not statistically significant after multiple comparison correction. DNAm AA associated with obesity (0.08, 95% CI 1.02, 1.16), hypertension (0.08, 95% CI 1.01, 1.17), and DM (0.20, 95% CI 1.09, 1.40), after adjustment for potential confounders.

Conclusions

Associations between age acceleration and depressive symptoms may be highly nuanced and dependent on study design contexts. Factors other than age acceleration may explain the connection between depressive symptoms and CM traits. AAW with CM traits may be at increased risk of accelerated aging.

Racial Discrimination, Mental Health, and Parenting Among African American Mothers of Preschool-Aged Children

OBJECTIVE

Indirect exposure to racism experienced by a caregiver (ie, vicarious racism) is associated with poor outcomes for children, but mechanisms of vicarious racism transmission are poorly understood. The purpose of this study was to examine the relationship between experiences of racial discrimination and parenting among African American mothers and to identify psychological mediators and moderators of this relationship.

METHOD

African American mothers (N = 250) with young children (mean age = 3.7 years old) reported on perceived racial discrimination (Race-Related Events Scale), parenting (Parenting Stress Index, Parenting Styles and Dimensions Questionnaire), coping (Coping Strategies Index), and mental health (Stress Overload Scale, Beck Depression Inventory). Multivariable linear regression was used to examine associations between perceived racial discrimination and parenting and to test coping as a moderator of these relationships. Ordinary least-squares regression-based path analysis with bootstrapping was used to examine mediation by stress overload and depressive symptoms.

RESULTS

At least one experience of racial discrimination was reported by 57% of women. Experiences of racial discrimination were associated with increased parenting stress (β = 0.69, p = .02), and this relationship was mediated by stress overload (95% CI [0.35, 1.09]) and depressive symptoms (95% CI [0.27, 1.18]). Racial discrimination was not associated with parenting styles, and coping strategies largely did not moderate the relationships examined.

CONCLUSION

Racial discrimination has harmful intergenerational effects on African American children and families. Systemic-level interventions are needed, including adoption of policies to promote racial justice and eliminate structural racism in the United States. Future research on coping strategies specific to racism-related stress is needed to inform approaches to intervention.

The accelerated aging phenotype: The role of race and social determinants of health on aging

The pursuit to discover the fundamental biology and mechanisms of aging within the context of the physical and social environment is critical to designing interventions to prevent and treat its complex phenotypes. Aging research is critically linked to understanding health disparities because these inequities shape minority aging, which may proceed on a different trajectory than the overall population. Health disparities are characteristically seen in commonly occurring age-associated diseases such as cardiovascular and cerebrovascular disease as well as diabetes mellitus and cancer. The early appearance and increased severity of age-associated disease among African American and low socioeconomic status (SES) individuals suggests that the factors contributing to the emergence of health disparities may also induce a phenotype of 'premature aging' or 'accelerated aging' or 'weathering'. In marginalized and low SES populations with high rates of early onset age-associated disease the interaction of biologic, psychosocial, socioeconomic and environmental factors may result in a phenotype of accelerated aging biologically similar to premature aging syndromes with increased susceptibility to oxidative stress, premature accumulation of oxidative DNA damage, defects in DNA repair and higher levels of biomarkers of oxidative stress and inflammation. Health disparities, therefore, may be the end product of this complex interaction in populations at high risk. This review will examine the factors that drive both health disparities and the accelerated aging phenotype that ultimately contributes to premature mortality.

Equity in Genomics: A Brief Report on Cardiovascular Health Disparities in African American Adults

BACKGROUND

African Americans are more likely to die from cardiovascular disease (CVD) than all other populations in the United States. Although technological advances have supported rapid growth in applying genetics/genomics to address CVD, most research has been conducted among European Americans. The lack of African American representation in genomic samples has limited progress in equitably applying precision medicine tools, which will widen CVD disparities if not remedied.

PURPOSE

This report summarizes the genetic/genomic advances that inform precision health and the implications for cardiovascular disparities in African American adults. We provide nurse scientists recommendations for becoming leaders in developing precision health tools that promote population health equity.

CONCLUSIONS

Genomics will continue to drive advances in CVD prevention and management, and equitable progress is imperative. Nursing should leverage the public's trust and its widespread presence in clinical and community settings to prevent the worsening of CVD disparities among African Americans.

The Association Between Neighborhood Social Vulnerability and Cardiovascular Health Risk Among Black/African American Women in the InterGEN Study

BACKGROUND

Black/African American women in the United States are more likely to live in neighborhoods with higher social vulnerability than other racial/ethnic groups, even when adjusting for personal income. Social vulnerability, defined as the degree to which the social conditions of a community affect its ability to prevent loss and suffering in the event of disaster, has been used in research as an objective measure of neighborhood social vulnerability. Black/African American women also have the highest rates of hypertension and obesity in the United States.

OBJECTIVES

The purpose of this study was to examine the relationship between neighborhood social vulnerability and cardiovascular risk (hypertension and obesity) among Black/African American women.

METHODS

We conducted a secondary analysis of data from the InterGEN Study that enrolled Black/African American women in the Northeast United States. Participants' addresses were geocoded to ascertain neighborhood vulnerability using the Centers for Disease Control and Prevention's Social Vulnerability Index at the census tract level. We used multivariable regression models to examine associations between objective measures of neighborhood quality and indicators of structural racism and systolic and diastolic blood pressure and obesity (body mass index > 24.9) and to test psychological stress, coping, and depression as potential moderators of these relationships.

RESULTS

Seventy-four percent of participating Black/African American women lived in neighborhoods in the top quartile for social vulnerability nationally. Women living in the top 10% of most socially vulnerable neighborhoods in our sample had more than a threefold greater likelihood of hypertension when compared to those living in less vulnerable neighborhoods. Objective neighborhood measures of structural racism (percentage of poverty, percentage of unemployment, percentage of residents >25 years old without a high school diploma, and percentage of residents without access to a vehicle) were significantly associated with elevated diastolic blood pressure and obesity in adjusted models. Psychological stress had a significant moderating effect on the associations between neighborhood vulnerability and cardiovascular risk.

DISCUSSION

We identified important associations between structural racism, the neighborhood environment, and cardiovascular health among Black/African American women. These findings add to a critical body of evidence documenting the role of structural racism in perpetuating health inequities and highlight the need for a multifaceted approach to policy, research, and interventions to address racial health inequities.

DNA methylation changes in African American women with a history of preterm birth from the InterGEN study

Background

Preterm birth (< 37 weeks’ gestation) is a common outcome of pregnancy that has been associated with increased risk of cardiovascular disease for women later in life. Little is known about the physiologic mechanisms underlying this risk. To date, no studies have evaluated if differences in DNA methylation (DNAm) among women who experience preterm birth are short-term or if they persist and are associated with subsequent cardiovascular sequelae or other health disorders. The purpose of this study was to examine long-term epigenetic effects of preterm birth in African American mothers (n = 182) from the InterGEN Study (2014–2019). In this study, we determine if differences in DNAm exist between women who reported a preterm birth in the last 3–5 years compared to those who had full-term births by using two different approaches: epigenome-wide association study (EWAS) and genome-wide co-methylation analyses.

Results

Though no significant CpG sites were identified using the EWAS approach, we did identify significant modules of co-methylation associated with preterm birth. Co-methylation analyses showed correlations with preterm birth in gene ontology and KEGG pathways. Functional annotation analysis revealed enrichment for pathways related to central nervous system and sensory perception. No association was observed between DNAm age and preterm birth, though larger samples are needed to confirm this further.

Conclusions

We identified differentially methylated gene networks associated with preterm birth in African American women 3–5 years after birth, including pathways related to neurogenesis and sensory processing. More research is needed to understand better these associations and replicate them in an independent cohort. Further study should be done in this area to elucidate mechanisms linking preterm birth and later epigenomic changes that may contribute to the development of health disorders and maternal mood and well-being.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12863-021-00988-x.

DNA Methylation, Preterm Birth and Blood Pressure in African American Children: The DPREG Study

Preterm birth (< 37 weeks) has been associated with high blood pressure (BP) and cardiovascular disease in adulthood. Epigenetic mechanisms may explain how preterm birth influences later BP. In this study, we examined the association between DNA methylation (DNAm), preterm birth and BP in African American children. We recruited 100 children and collected clinical and birth history data. DNA was extracted from saliva and the Illumina EPIC BeadChip was used for epigenetic analyses. Preterm birth was not associated with systolic or diastolic BP. No significant DNAm sites were associated with preterm birth in candidate gene methylation analyses. Body mass index was associated with systolic BP (p = 0.01). We did not observe an effect of preterm birth on DNAm or BP in early childhood. Our study is one of the few, however, to examine these associations among African Americans.

Associations between social determinants of health, perceived discrimination, and body mass index on symptoms of depression among young African American mothers

PURPOSE

The association between symptoms of depression and risks for cardiovascular disease (CVD) remains equivocal for African American (AA) mothers. We examined the association between social determinants of health (perceived discrimination), and cardiovascular risk (BMI) on symptoms of depression in a sample of young AA mothers.

METHODS

Secondary data from 219 adult AA mothers between the ages of 21 and 46 with an average BMI of 29.8 and yearly family income of $14,999 were analyzed using a latent growth model that evaluated four time points to assess changes in symptoms of depression.

RESULTS

Initial BMI was significantly associated with initial symptoms of depression (b = 0.12, p = .019). Perceived discrimination (unfair treatment) was associated with higher initial symptoms of depression (b = 1.14, p = .017).

CONCLUSION

The findings suggest that elevated BMI and perceived discrimination are associated with higher reported symptoms of depression among young, socioeconomically disadvantaged AA mothers. These results advance the scientific understanding of young AA mothers' risk for symptoms of depression and CVD by elucidating the impact of perceived discrimination and social experiences on mental health. Further studies of SDoH and CVD risk factors and perceived racism and depression are needed to shed light on the long-term mental health impact on AA mothers and their children.

Exploring Psychosocial Mediators of the Associations of Lifetime Trauma and Body Mass Index in African American Women

Purpose: This study sought to examine the association between lifetime trauma (i.e., childhood, adulthood, and cumulative) and body mass index (BMI) and if this association was mediated by psychosocial factors (i.e., depressive symptoms and stress) in a sample of African American women.

Methods: We examined lifetime trauma among African American women in the Intergenerational Impact of Genetic and Psychological Factors on Blood Pressure Study (InterGEN) study. We conducted mediation analyses with bootstrapping to assess the direct and indirect effects of increasing forms of trauma across the lifespan on BMI. Depressive symptoms and stress were examined as mediators of these associations.

Results: The analytic sample included 138 women with a mean age of 31.9 years. Approximately half of women reported any childhood trauma (47.8%) and more than half (73.2%) reported any adulthood trauma. The direct effects of all forms of trauma were associated with greater depressive symptoms. Only lifetime trauma was associated with higher stress overload (B=2.40, standard error [SE]=1.12, p<0.05). Higher depressive symptoms were associated with higher BMI in all models. The indirect effects of adulthood trauma (B=0.60, SE=0.20, p<0.01) and lifetime trauma (B=0.53, SE=0.20, p<0.01) on BMI were partially mediated by depressive symptoms.

Conclusion: These findings indicate that depressive symptoms mediate the associations between adulthood and lifetime trauma with BMI. Interventions aimed at reducing elevated BMI in African American women should account for the influence of depressive symptoms. Future research should replicate these analyses in other samples of African American women.

Examining Mother-Reported Poor Sleep and Blood Pressure in Black/African American Mother-Child Dyads

BACKGROUND

Poor sleep is a confirmed risk factor for hypertension (HTN), and Black/African American (AA) women have among the highest rates of HTN in the United States.

OBJECTIVE

We examined the relationship between sleep and blood pressure (BP) among Black/AA mother-child dyads using data from the Intergenerational Impact of Genetic and Psychological Factors on Blood Pressure study.

METHODS

Data for this study were derived from 250 Black/AA mother-child dyads from low-income neighborhoods, collected via 4 home visits over 2 years. Mothers reported poor sleep, including reports of sleeping worse than usual and nighttime awakenings. Recordings of BP were obtained for mother and child. Mother BP was scored as normal (<120/<80 mm Hg), elevated (120-129/<80 mm Hg), stage 1 HTN (130-139/80-89 mm Hg), or stage 2 HTN (systolic ≥140 or diastolic ≥90 mm Hg). Generalized linear models examined the relationships between mother-reported poor sleep variables and both mother and child BP. Adjusted models examining mother BP controlled for the mother's age, education, marital status, smoking, body mass index, and depression symptoms.

RESULTS

In adjusted models, nighttime awakenings were associated with stage 2 HTN (b = 2.70, 95% confidence interval [CI], 0.54-4.86, P < .05). Compared with children whose mother who had normal BP, children whose mother had elevated BP had higher diastolic BP (b = 0.37; 95% CI, 0.19-0.54; P < .001). Mother elevated BP was associated with both child systolic BP (b = 2.49; 95% CI, 0.44-4.53; P < .05) and diastolic BP (b = 2.07; 95% CI, 0.39-3.76; P < .05). Mother stage 1 HTN was associated with both child systolic BP (b = 2.16; 95% CI, 0.29-4.03; P < .05) and diastolic BP (b = 3.91; 95% CI, 2.40-5.42; P < .001). We detected a significant interaction between mother stage 2 HTN and mother nighttime awakenings in predicting higher child diastolic BP (b = 8.16; 95% CI, 0.65-15.68; P < .05).

CONCLUSIONS

We found evidence for an association between mothers' nighttime awakenings and very high BP. Our study also illuminated a strong relationship between high mother BP and high child BP. Finally, our study found preliminary support for the potentially mediating role of mothers' nighttime awakenings in predicting the relationship between mother stage 2 HTN and child BP.

High blood pressure in pregnancy, DNA methylation, and later blood pressure in African American women enrolled in the InterGEN Study

BACKGROUND

Few studies have examined the effects of high blood pressure (BP) in pregnancy, preeclampsia, or eclampsia on later BP, and the epigenetics of this phenomenon is similarly poorly understood, especially among African Americans. The purpose of this study was to examine the association between high BP in pregnancy, epigenomics, and later BP in African American women in the InterGEN Study (n = 250).

METHODS

In cross-sectional analyses, regression and linear mixed-effects models were employed to examine the effects of high BP in pregnancy on: (a) epigenetic associations (DNA methylation) and (b) BP 3-5 years after birth. The 850K Illumina EPIC BeadChip was used for evaluating epigenome-wide DNA methylation. High BP in pregnancy, preeclampsia, or eclampsia was self-reported by women, and BP was measured 3-5 years after birth, per JNC-7 guidelines. DNA methylation and clinical BP were the main outcomes.

RESULTS

Mean age of enrolled women was 31.2 years, 21.8% were smokers, 58% had some college or higher education, 46.6% reported an annual income <$15 000, and 13.6% reported high BP in pregnancy. After adjustment for obesity, smoking, and age, women with a history of high BP in pregnancy had significantly higher BP than those who did not report this complication (5.39 ± 2.4 mm Hg, P = .030). Epigenome-wide analysis revealed no significant sites after multiple testing correction.

CONCLUSIONS

We observed a small, but clinically significant, increase in BP in women who reported high BP in pregnancy 3-5 years after that pregnancy. Future studies with larger sample sizes should examine epigenetic contributions to this finding.

African American mothers' attitudes towards genetic testing in the InterGEN study

The paucity of representation of people of color, particularly those of African ancestry, is a major issue in contemporary omics research. Metadata summarizing genome-wide association studies from 2005 to 2015 suggest that nearly 80% of participants are of European ancestry and only 2.4% are of African ancestry. Negative attitude towards genetic testing is a commonly cited belief as to why there is low representation of Americans of African ancestry participating in genetic studies. Using the attitudes towards genetic testing survey, administered as part of our parent (epi)genome-wide association study, we characterized the perceptions of genetic research among our cohort of African ancestry women (n = 168). Our data show generally favorable perceptions of genetic testing among our cohort. Further, we demonstrate that more favorable attitudes towards genetic testing correlated with higher levels of income, even when accounting for commonly cited negative predictors such as maternal age, education, country of origin, and religion. Overall, our data characterize generally positive perceptions of genetic testing among women of African ancestry.

The Influence of Discrimination and Coping Style on Blood Pressure Among Black/African American Women in the InterGEN Study

Purpose: Although research has explored the effects of racism on mental health, few studies have investigated the effects of racism on physical health. In this study, we examined the influence of racial discrimination and race-related stress and coping on blood pressure within a cohort of Black/African American women. Methods: This was a secondary data analysis of 226 Black/African American women from the Intergenerational Impact of Genetic and Psychological Factors on Blood Pressure study. Experiences of racial discrimination and coping, measured by the Experiences of Discrimination scale and the Race-Related Events Scale, were analyzed in relation to systolic blood pressure (SBP) and diastolic blood pressure (DBP). Multiple linear regression was used to explore the interaction effect of coping and discrimination on blood pressure for both scales. Results: Age and elevated body mass index were associated with increased SBP and DBP, and low income was associated with increased DBP. Among individuals who reported no personal experience of discrimination, more active coping strategies were associated with higher DBP. There was no evidence of a relationship between type of coping strategies used and blood pressure among individuals who did report experiences of discrimination. Conclusion: Differences in coping strategy in response to racism were not found to have a significant moderating effect on DBP in Black/African American women.

Efficient detection of differentially methylated regions in the genome of patients with thoracic aortic dissection and association with MMP2 hypermethylation

DNA methylation is known to regulate the expression of numerous genes but its role in the pathogenesis of thoracic aortic dissection (TAD) has remained largely elusive. In the present study, the DNA methylome of patients with TAD was analyzed using a methylation microarray and bisulfite pyrosequencing was used to determine whether the hypermethylation of matrix metalloproteinase 2 (MMP2) specifically is associated with TAD. Chip-based whole-DNA methylome analysis was performed on 4 male patients with TAD and 4 male healthy controls using an Illumina HumanMethylation EPIC 850K BeadChip. The resulting data were analyzed by clustering and principal component analysis, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed on the differentially methylated genes to interrogate their biological functions. Compared to the healthy controls, 3,362 loci were differentially methylated in the patients with TAD with a statistical significance of P<0.05, while 1,223 loci had a significance of P<0.01. Among these loci, 2,019 were hypermethylated and 1,343 were hypomethylated. From GO analysis within the biological process category, the MMP2, MMP14 and WNT2B genes were identified. enrichment was observed for loci involved in cellular component organization, enzyme-linked receptor protein signaling pathways (potentially having a key role in the development of cardiopulmonary function disorders) and vascular reconstruction. Bisulfite pyrosequencing of plasma samples indicated significantly increased methylation (P<0.01) of the CpG site at position 2 in the promoter of MMP2 in the TAD group relative to the healthy controls, and the mean methylation level of four CpG sites on the MMP2 gene in the TAD group was slightly higher than that in the control group, but not significantly. Hypermethylation of the MMP2 promoter may be a promising novel diagnostic and prognostic biomarker for TAD. Future studies on the epigenetics of biomarkers linked to vascular reconstruction and immune function may provide further insight into the pathogenesis and progression of TAD.

Stress, Resilience, and Cardiovascular Disease Risk Among Black Women

BACKGROUND

Empirical data on the link between stress and cardiovascular disease (CVD) risk among black women is limited. We examined associations of stressful life events and social strain with incident CVD among black women and tested for effect modification by resilience.

METHODS AND RESULTS

Our analysis included 10 785 black women enrolled in the Women's Health Initiative Observational Study and Clinical Trials cohort. Participants were followed for CVD for up to 23 years (mean, 12.5). Multivariable Cox regression was used to estimate hazard ratios and 95% CIs for associations between stress-related exposures and incident CVD. We included interactions between follow-up time (age) and stressful life events because of evidence of nonproportional hazards. Effect modification by resilience was examined in the sub-cohort of 2765 women with resilience and stressful life events measures. Higher stressful life events were associated with incident CVD at ages 55 (hazard ratio for highest versus lowest quartile=1.80; 95% CI, 1.27-2.54) and 65 (hazard ratio for highest versus lowest quartile=1.40; 95% CI, 1.16-1.68), but not at older ages. Adjustment for CVD risk factors attenuated these associations. Similar associations were observed for social strain. In the sub-cohort of women with updated stressful life events and resilience measures, higher stressful life events were associated with incident CVD in multivariable-adjusted models (hazard ratio=1.61; 95% CI, 1.04-2.51). Resilience did not modify this association nor was resilience independently associated with incident CVD.

CONCLUSIONS

In this cohort of older black women, recent reports of stressful life events were related to incident CVD. Resilience was unrelated to incident CVD.

CLINICAL TRIALS REGISTRATION

URL: https://www.clinicaltrials.gov . Unique identifier: NCT00000611.

Genomics of Reproductive Traits and Cardiometabolic Disease Risk in African American Women

BACKGROUND

Age at menarche and age at natural menopause occur significantly earlier in African American women than in other ethnic groups. African American women also have twice the prevalence of cardiometabolic disorders related to the timing of these reproductive traits.

OBJECTIVES

The objectives of this integrative review were to (a) summarize the genome-wide association studies of reproductive traits in African American women, (b) identify genes that overlap with reproductive traits and cardiometabolic risk factors in African American women, and (c) propose biological mechanisms explaining the link between reproductive traits and cardiometabolic risk factors.

METHODS

PubMed was searched for genome-wide association studies of genes associated with reproductive traits in African American women. After extracting and summarizing the primary genes, we examined whether any of the associations with reproductive traits had also been identified with cardiometabolic risk factors in African American women.

RESULTS

Seven studies met the inclusion criteria. Associations with both reproductive and cardiometabolic traits were reported in or near the following genes: FTO, SEC16B, TMEM18, APOE, PHACTR1, KCNQ1, LDLR, PIK3R1, and RORA. Biological pathways implicated include body weight regulation, vascular homeostasis, and lipid metabolism.

DISCUSSION

A better understanding of the genetic basis of reproductive traits in African American women may provide insight into the biological mechanisms linking variation in these traits with increased risk for cardiometabolic disorders in this population.

Prediagnostic Allostatic Load as a Predictor of Poorly Differentiated and Larger Sized Breast Cancers among Black Women in the Women's Circle of Health Follow-Up Study

BACKGROUND

Few studies have empirically tested the association of allostatic load (AL) with breast cancer clinicopathology. The aim of this study was to examine the association of AL, measured using relevant biomarkers recorded in medical records before breast cancer diagnosis, with unfavorable tumor clinicopathologic features among Black women.

METHODS

In a sample of 409 Black women with nonmetastatic breast cancer who are enrolled in the Women's Circle of Health Follow-Up Study, we estimated prediagnostic AL using two measures: AL measure 1 [lipid profile-based-assessed by systolic and diastolic blood pressure (SBP, DBP), high-density lipoprotein, low-density lipoprotein, total cholesterol, triglycerides, and glucose levels; waist circumference; and use of diabetes, hypertension, or hypercholesterolemia medication] and AL measure 2 (inflammatory index-based-assessed by SBP, DBP, glucose, and albumin levels; estimated glomerular filtration rate; body mass index; waist circumference; and use of medications previously described). We used Cohen's statistic to assess agreement between the two AL measures and multivariable logistic models to assess the associations of interest.

RESULTS

AL measures 1 and 2 moderately agreed (κ = 0.504). Higher prediagnostic AL predicted higher grade (poorly differentiated vs. well/moderately differentiated) using AL measure 1 [OR = 2.16; 95% confidence interval (CI), 1.18-3.94] and AL measure 2 (OR = 1.60; 95% CI, 1.02-2.51), and larger tumor size (≥2 cm vs. <2 cm; OR = 1.58; 95% CI, 1.01-2.46) using AL measure 2 only.

CONCLUSIONS

Elevated prediagnostic AL might contribute to more unfavorable breast cancer clinicopathology.

IMPACT

Addressing elevated prediagnostic levels of AL has potentially important clinical implications.

Association Between Stress and Coping with DNA Methylation of Blood Pressure-Related Genes Among African American Women

Background

Exposure to psychosocial stress and employment of high effort coping strategies have been identified as risk factors that may partially explain the high prevalence of hypertension among African Americans. One biological mechanism through which stress and coping may affect risk of hypertension is via epigenetic modifications (e.g., DNA methylation) in blood pressure-related genes; however, this area remains understudied in African Americans.

Methods

We used data from the ongoing Intergenerational Blood Pressure Study, a longitudinal study designed to investigate factors that contribute to hypertension risk in African American women (n = 120) and their young children, to investigate the association between stress overload, problem-solving coping, avoidance coping, and social support coping with DNA methylation in 25 candidate genes related to blood pressure. Multivariable linear regression and multilevel modeling were used to conduct methylation site-level and gene-level analyses, respectively.

Results

In site-level analyses, stress overload, problem-solving coping, social support coping, and avoidance coping were associated with 47, 63, 66, and 61 sites, respectively, at p < 0.05. However, no associations were statistically significant after multiple testing correction. There were also no significant associations in gene-level analyses.

Conclusions

As human social epigenomics is an emerging, evolving area of research, there is much to be learned from studies with statistically significant findings as well as studies with null findings. Factors such as characteristics of the social stressor, source of DNA, and synchronization of exposure and outcome are likely important considerations as we move the field forward.

Association of Obesity with DNA Methylation Age Acceleration in African American Mothers from the InterGEN Study

African American women are affected by earlier onset of age-associated health deteriorations and obesity disproportionally, but little is known about the mechanism linking body mass index (BMI) and biological aging among this population. DNA methylation age acceleration (DNAm AA), measuring the difference between DNA methylation age and chronological age, is a novel biomarker of the biological aging process, and predicts aging-related disease outcomes. The present study estimated cross-tissue DNA methylation age acceleration using saliva samples from 232 African American mothers. Cross-sectional regression analyses were performed to assess the association of BMI with DNAm AA. The average chronological age and DNA methylation age were 31.67 years, and 28.79 years, respectively. After adjusting for smoking, hypertension diagnosis history, and socioeconomic factors (education, marital status, household income), a 1 kg/m² increase in BMI is associated with 0.14 years increment of DNAm AA (95% CI: (0.08, 0.21)). The conclusion: in African American women, high BMI is independently associated with saliva-based DNA methylation age acceleration, after adjusting for smoking, hypertension, and socioeconomic status. This finding supports that high BMI accelerates biological aging, and plays a key role in age-related disease outcomes among African American women.

Novel DNA methylation sites associated with cigarette smoking among African Americans

INTRODUCTION

Cigarette smoking has been associated with adverse health outcomes for mothers and children and is a major contributor to heart disease. Although cigarette smoking is known to affect the epigenome, few studies have been done in African American populations. In this study, we investigated the association between cigarette smoking and DNA methylation (DNAm) among African Americans from the Intergenerational Impact of Genetic and Psychological Factors on Blood Pressure Study (InterGEN), and the Genetic Epidemiology Network of Arteriopathy (GENOA).

METHODS

The InterGEN study aims to examine the effects of genetic and psychological factors on blood pressure among African American women and their children. Current cigarette smoking was assessed at baseline. DNAm of saliva was assessed using the 850K EPIC Illumina BeadChip for Epigenome-Wide Association analyses. A replication study was conducted among 1100 participants in the GENOA study using the same BeadChip.

RESULTS

After controlling for age, body mass index, population structure and cell composition, 26 epigenome-wide significant sites (FDR q < 0.05) were identified, including the AHRR and PHF14 genes associated with atherosclerosis and lung disease, respectively. Six novel CpG sites were discovered in the InterGEN sample and replicated in the GENOA sample. Genes mapped include RARA, FSIP1, ALPP, PIK3R5, KIAA0087, and MGAT3, which were largely associated with cancer development.

CONCLUSION

We observed significant epigenetic associations between smoking and disease-associated genes (e.g., cardiovascular disease, lung cancer). Six novel CpG sites were identified and replicated across saliva and blood samples.

NuRsing Research in the 21st Century: R You Ready?

Nurse scientists are adept at translating findings from basic science into useful clinical- and community-based interventions to improve health. Over time, the focus of some nursing research has grown to include the assessment and evaluation of genomic and other output from high-throughput, or "omic," technologies as indicators related to health and disease. To date, the growth in the application of omics technologies in nursing research has included calls to increase attention to omics in nursing school curricula and educational training opportunities, such as the Summer Genetics Institute offered by the National Institute of Nursing Research. However, there has been scant attention paid in the nursing literature to the complexity of data analysis or issues of reproducibility related to omics studies. The goals of this article are to (1) familiarize nurse scientists with tools that encourage reproducibility in omics studies, with a focus on the free and open-source data processing and analysis pipeline, and (2) provide a baseline understanding of how these tools can be used to improve collaboration and cohesion among interdisciplinary research team members. Knowledge of these tools and skill in applying them will be important for communication across disciplines and imperative for the advancement of omics research in nursing.

Parenting stress and DNA methylation among African Americans in the InterGEN Study

Introduction

General life stress has been associated with altered DNA methylation in individuals of African Ancestry, although the relationship between parenting stress and DNA methylation has not been described. The purpose of this study was to examine the relationship between maternal parenting stress and DNA methylation among African Ancestry mother-child dyads.

Methods

We evaluated epigenome-wide DNA methylation relative to parenting stress in 74 mother-child dyads using linear mixed models.

Results

Significant variation in maternal DNA methylation at 95 CpG sites was associated with level of parenting stress. Notably, we identified a change in DNA methylation associated with poly (ADP-ribose) polymerase-1, which plays a key role in stress signaling. We did not identify any significant variation in child DNA methylation related to maternal parenting stress.

Conclusions

However, DNA methylation patterns observed in children mirrored patterns observed in their mothers. The results suggest that differential maternal DNA methylation is associated with higher levels of parenting stress.

Perceived Racial Discrimination and DNA Methylation Among African American Women in the InterGEN Study

INTRODUCTION

Experiences of racial discrimination have been associated with poor health outcomes. Little is known, however, about how perceived racial discrimination influences DNA methylation (DNAm) among African Americans (AAs). We examined the association of experiences of discrimination with DNAm among AA women in the Intergenerational Impact of Genetic and Psychological Factors on Blood Pressure (InterGEN) study.

METHODS

The InterGEN study examines the effects of genetic and psychological factors on blood pressure among AA women and their children. Measures include the Major Life Discrimination (MLD) and the Race-Related Events (RES) scales. In the present analysis, we examined discrimination and DNAm at baseline in the InterGEN study. The 850K EPIC Illumina BeadChip was used for evaluating DNAm in this epigenome-wide association study (EWAS).

RESULTS

One hundred and fifty-two women contributed data for the RES-EWAS analysis and 147 for the MLD-EWAS analysis. Most were 30-39 years old, nonsmokers, had some college education, and had incomes

CONCLUSION

We observed significant epigenetic associations between disease-associated genes (e.g., schizophrenia, bipolar disorder, and asthma) and perceived discrimination as measured by the MLD Scale. Future health disparities research should include epigenetics in high-risk populations to elucidate functional consequences induced by the psychosocial environment.

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Key Words

• African Americans
• DNA methylation
• epigenomics
• racism
• women

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MESH Headings

• Adult
• Black or African American/genetics
• Asthma/genetics
• Blood Pressure/genetics
• Child
• DNA/analysis
• DNA Methylation/genetics
• Epigenesis, Genetic
• Epigenomics
• Female
• Humans
• Racism
• Risk Factors
• United States

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Grants

• R01 NR013520 NINR NIH HHS
• UL1 TR001863 NCATS NIH HHS
• National Institute of Nursing Research

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Affiliation(s)

Veronica Barcelona de Mendoza 1 Yale School of Nursing, Orange, CT, USA
Yunfeng Huang 2 Department of Epidemiology, Emory University Rollins School of Public Health, Atlanta, GA, USA
Cindy A Crusto 3 Department of Psychiatry, Yale School of Medicine, New Haven, CT, USA
Yan V Sun 2 Department of Epidemiology, Emory University Rollins School of Public Health, Atlanta, GA, USA
Jacquelyn Y Taylor 1 Yale School of Nursing, Orange, CT, USA

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Joint Influence of SNPs and DNA Methylation on Lipids in African Americans From Hypertensive Sibships

INTRODUCTION

Plasma concentrations of lipids (i.e., total cholesterol, high-density cholesterol, low-density cholesterol, and triglycerides) are amenable to therapeutic intervention and remain important factors for assessing risk of cardiovascular diseases. Some of the observed variability in serum lipid concentrations has been associated with genetic and epigenetic variants among cohorts with European ancestry (EA). Serum lipid levels have also been associated with genetic variants in multiethnic populations.

METHODS

The purpose of this study was to determine whether single-nucleotide polymorphisms (SNPs) and DNA methylation (DNAm) differences contribute to lipid variation among African Americans ([AAs], N = 739) in the Genetic Epidemiology Network of Arteriopathy (GENOA) study.

RESULTS

Previous meta-analyses identified 161 SNPs that are associated with lipid traits in populations of EA. We evaluated these SNPs and 66 DNAm sites within the genes containing the SNPs in the GENOA cohort using linear mixed-effects modeling. We did not identify any significant associations of SNPs or DNAm with serum lipid levels. These results suggest that the SNPs identified as being significant for lipid levels through the EA genome-wide association studies may not be significant across AA populations.

CONCLUSIONS

Reductions in morbidity and mortality due to variation in lipids among AAs may be achieved through a better understanding of the genetic and epigenetic factors associated with serum lipid levels for early and appropriate screening. Further large-scale studies specifically within AA and other non-EA populations are warranted.

Improving -Omics-Based Research and Precision Health in Minority Populations: Recommendations for Nurse Scientists

PURPOSE

The purpose of this article is to provide an overview of the role of nurse scientists in -omics-based research and to promote discussion around the conduct of -omics-based nursing research in minority communities. Nurses are advocates, educators, practitioners, scientists, and researchers, and are crucial to the design and successful implementation of -omics studies, particularly including minority communities. The contribution of nursing in this area of research is crucial to reducing health disparities.

METHODS

In this article, challenges in the conduct of -omics-based research in minority communities are discussed, and recommendations for improving diversity among nurse scientists, study participants, and utilization of training and continuing education programs in -omics are provided.

FINDINGS AND CONCLUSIONS

Many opportunities exist for nurses to increase their knowledge in -omics and to continue to build the ranks of nurse scientists as leaders in -omics-based research. In order to work successfully with communities of color, nurse scientists must advocate for participation in the Precision Medicine Initiative, improve representation of nurse faculty of color, and increase utilization of training programs in -omics and lead such initiatives.

CLINICAL RELEVANCE

All nursing care has the potential to be affected by the era of -omics and precision health. By taking an inclusive approach to diversity in nursing and -omics research, nurses will be well placed to be leaders in reducing health disparities through research, practice, and education.

The combined effects of genetic risk and perceived discrimination on blood pressure among African Americans in the Jackson Heart Study

Both genomics and environmental stressors play a significant role in increases in blood pressure (BP). In an attempt to further explain the hypertension (HTN) disparity among African Americans (AA), both genetic underpinnings (selected candidate genes) and stress due to perceived racial discrimination (as reported in the literature) have independently been linked to increased BP among AAs. Although Gene x Environment interactions on BP have been examined, the environmental component of these investigations has focused more on lifestyle behaviors such as smoking, diet, and physical activity, and less on psychosocial stressors such as perceived discrimination.The present study uses candidate gene analyses to identify the relationship between Everyday Discrimination (ED) and Major Life Discrimination (MLD) with increases in systolic BP (SBP) and diastolic BP (DBP) among AA in the Jackson Heart Study. Multiple linear regression models reveal no association between discrimination and BP after adjusting for age, sex, body mass index (BMI), antihypertensive medication use, and current smoking status.Subsequent candidate gene analysis identified 5 SNPs (rs7602215, rs3771724, rs1006502, rs1791926, and rs2258119) that interacted with perceived discrimination and SBP, and 3 SNPs (rs2034454, rs7602215, and rs3771724) that interacted with perceived discrimination and DBP. Most notably, there was a significant SNP × discrimination interaction for 2 SNPs on the SLC4A5 gene: rs3771724 (MLD: SBP P = .034, DBP P = .031; ED: DBP: P = .016) and rs1006502 (MLD: SBP P = .034, DBP P = .030; ED: DBP P = .015).This study supports the idea that SNP × discrimination interactions combine to influence clinically relevant traits such as BP. Replication with similar epidemiological samples is required to ascertain the role of genes and psychosocial stressors in the development and expression of high BP in this understudied population.

The Intergenerational Impact of Genetic and Psychological Factors on Blood Pressure Study (InterGEN): Design and Methods for Recruitment and Psychological Measures

BACKGROUND

Although studies show that genomics and environmental stressors affect blood pressure, few studies have examined their combined effects, especially in African Americans.

OBJECTIVE

We present the recruitment methods and psychological measures of the Intergenerational Impact of Genetic and Psychological Factors on Blood Pressure (InterGEN) study, which seeks to investigate the individual and combined effects of genetic (G) and environmental (E) (psychological) stressors on blood pressure in African American mother-child dyads. Genetic methods are presented elsewhere, but here we present the recruitment methods, psychological measures, and analysis plan for these environmental stressors.

METHODS

This longitudinal study will enroll 250 mother-child dyads (N = 500). Study participation is restricted to women who (a) are ≤21 years of age, (b) self-identify as African American or Black, (c) speak English, (d) do not have an identified mental illness or cognitive impairment, and (e) have a biological child between 3 and 5 years old. The primary environmental stressors assessed are parenting stress, perceived racism and discrimination, and maternal mental health. Covariates include age, cigarette smoking (for mothers), and gender (for children). The study outcome variables are systolic and diastolic blood pressure.

ANALYSIS

The main analytic outcome is genetic-by-environment interaction analyses (G × E); however, main effects (G) and (E) will be individually assessed first. Genetic (G) and interaction analyses (G × E) are described in a companion paper and will include laboratory procedures. Statistical modeling of environmental stressors on blood pressure will be done using descriptive statistics and generalized estimating equation models.

IMPLICATIONS

The methodology presented here includes the study rationale, community engagement and recruitment protocol, psychological variable measurement, and analysis plan for assessing the association of environmental stressors and blood pressure. This study may provide the foundation for other studies and development of interventions to reduce the risk for hypertension and to propose targeted health promotion programs for this high-risk population.

A Systematic Review of DNA Methylation and Preterm Birth in African American Women

BACKGROUND

The causes of many cases of preterm birth (PTB) remain enigmatic. Increased understanding of how epigenetic factors are associated with health outcomes has resulted in studies examining DNA methylation (DNAm) as a contributing factor to PTB. However, few studies on PTB and DNAm have included African American women, the group with the highest rate of PTB.

METHODS

The objective of this review was to systematically analyze the existing studies on DNAm and PTB among African American women.

RESULTS

Studies ( N = 10) were limited by small sample size, cross-sectional study designs, inconsistent methodologies for epigenomic analysis, and evaluation of different tissue types across studies. African Americans comprised less than half of the sample in 50% of the studies reviewed. Despite these limitations, there is evidence for an association between DNAm patterns and PTB.

CONCLUSIONS

Future research on DNAm patterns and PTB should use longitudinal study designs, repeated DNAm testing, and a clinically relevant definition of PTB and should include large samples of high-risk African American women to better understand the mechanisms for PTB in this population.