Amy L. Non

Genome-wide DNA methylation in neonates exposed to maternal depression, anxiety, or SSRI medication during pregnancy

Despite the high prevalence of depression, anxiety, and use of antidepressant medications during pregnancy, there is much uncertainty around the impact of high levels of distress or antidepressant medications on the developing fetus. These intrauterine exposures may lead to epigenetic alterations to the DNA during this vulnerable time of fetal development, which may have important lifetime health consequences. In this study we investigated patterns of genome-wide DNA methylation using the Illumina Infinium Human Methylation450 BeadChip in the umbilical cord blood of neonates exposed to non-medicated maternal depression or anxiety (n = 13), or selective serotonin reuptake inhibitors (SSRIs) during pregnancy (n = 22), relative to unexposed neonates (n = 23). We identified 42 CpG sites with significantly different DNA methylation levels in neonates exposed to non-medicated depression or anxiety relative to controls. CpG site methylation was not significantly different in neonates exposed to SSRIs relative to the controls, after adjusting for multiple comparisons. In neonates exposed either to non-medicated maternal depression or SSRIs, the vast majority of CpG sites displayed lower DNA methylation relative to the controls, but differences were very small. A gene ontology analysis suggests significant clustering of the top genes associated with non-medicated maternal depression/anxiety, related to regulation of transcription, translation, and cell division processes (e.g., negative regulation of translation in response to oxidative stress, regulation of mRNA export from the nucleus, regulation of stem cell division). While the functional consequences of these findings are yet to be determined, these small DNA methylation differences may suggest a possible role for epigenetic processes in the development of neonates exposed to non-medicated maternal depression/anxiety.

Genetic Ancestry, Social Classification, and Racial Inequalities in Blood Pressure in Southeastern Puerto Rico

Background The role of race in human genetics and biomedical research is among the most contested issues in science. Much debate centers on the relative importance of genetic versus sociocultural factors in explaining racial inequalities in health. However, few studies integrate genetic and sociocultural data to test competing explanations directly. Methodology/Principal Findings We draw on ethnographic, epidemiologic, and genetic data collected in southeastern Puerto Rico to isolate two distinct variables for which race is often used as a proxy: genetic ancestry versus social classification. We show that color, an aspect of social classification based on the culturally defined meaning of race in Puerto Rico, better predicts blood pressure than does a genetic-based estimate of continental ancestry. We also find that incorporating sociocultural variables reveals a new and significant association between a candidate gene polymorphism for hypertension (α2C adrenergic receptor deletion) and blood pressure. Conclusions/Significance This study addresses the recognized need to measure both genetic and sociocultural factors in research on racial inequalities in health. Our preliminary results provide the most direct evidence to date that previously reported associations between genetic ancestry and health may be attributable to sociocultural factors related to race and racism, rather than to functional genetic differences between racially defined groups. Our results also imply that including sociocultural variables in future research may improve our ability to detect significant allele-phenotype associations. Thus, measuring sociocultural factors related to race may both empower future genetic association studies and help to clarify the biological consequences of social inequalities.

Internal Diversification of Mitochondrial Haplogroup R0a Reveals Post-Last Glacial Maximum Demographic Expansions in South Arabia

Widespread interest in the first successful Out of Africa dispersal of modern humans ∼60-80 thousand years ago via a southern migration route has overshadowed the study of later periods of South Arabian prehistory. In this work, we show that the post-Last Glacial Maximum period of the past 20,000 years, during which climatic conditions were becoming more hospitable, has been a significant time in the formation of the extant genetic composition and population structure of this region. This conclusion is supported by the internal diversification displayed in the highly resolved phylogenetic tree of 89 whole mitochondrial genomes (71 being newly presented here) for haplogroup R0a-the most frequent and widespread haplogroup in Arabia. Additionally, two geographically specific clades (R0a1a1a and R0a2f1) have been identified in non-Arabic speaking peoples such as the Soqotri and Mahri living in the southern part of the Arabian Peninsula where a past refugium was identified by independent archaeological studies. Estimates of time to the most recent common ancestor of these lineages match the earliest archaeological evidence for seafaring activity in the peninsula in the sixth millennium BC.

Early origins of inflammation: An examination of prenatal and childhood social adversity in a prospective cohort study

BACKGROUND Children exposed to social adversity carry a greater risk of poor physical and mental health into adulthood. This increased risk is thought to be due, in part, to inflammatory processes associated with early adversity that contribute to the etiology of many adult illnesses. The current study asks whether aspects of the prenatal social environment are associated with levels of inflammation in adulthood, and whether prenatal and childhood adversity both contribute to adult inflammation. METHODS We examined associations of prenatal and childhood adversity assessed through direct interviews of participants in the Collaborative Perinatal Project between 1959 and 1974 with blood levels of C-reactive protein in 355 offspring interviewed in adulthood (mean age=42.2 years). Linear and quantile regression models were used to estimate the effects of prenatal adversity and childhood adversity on adult inflammation, adjusting for age, sex, and race and other potential confounders. RESULTS In separate linear regression models, high levels of prenatal and childhood adversity were associated with higher CRP in adulthood. When prenatal and childhood adversity were analyzed together, our results support the presence of an effect of prenatal adversity on (log) CRP level in adulthood (β=0.73, 95% CI: 0.26, 1.20) that is independent of childhood adversity and potential confounding factors including maternal health conditions reported during pregnancy. Supplemental analyses revealed similar findings using quantile regression models and logistic regression models that used a clinically-relevant CRP threshold (>3mg/L). In a fully-adjusted model that included childhood adversity, high prenatal adversity was associated with a 3-fold elevated odds (95% CI: 1.15, 8.02) of having a CRP level in adulthood that indicates high risk of cardiovascular disease. CONCLUSIONS Social adversity during the prenatal period is a risk factor for elevated inflammation in adulthood independent of adversities during childhood. This evidence is consistent with studies demonstrating that adverse exposures in the maternal environment during gestation have lasting effects on development of the immune system. If these results reflect causal associations, they suggest that interventions to improve the social and environmental conditions of pregnancy would promote health over the life course. It remains necessary to identify the mechanisms that link maternal conditions during pregnancy to the development of fetal immune and other systems involved in adaptation to environmental stressors.

Race-related health disparities and biological aging: does rate of telomere shortening differ across blacks and whites?

Recent work suggests that leukocyte telomere length (LTL), a marker of cellular aging, is sensitive to effects of social stress and may also provide early indication of premature aging. Using data from a birth cohort with LTL information at birth and in middle adulthood we examined a potential source of race-based health disparity by testing the hypothesis that Blacks would demonstrate a faster rate of telomere shortening than Whites. Linear regression analyses were conducted and adjusted for pack years, BMI, education and social factors, diet, exercise, marital status, and age. At birth black individuals had LTLs that were longer, on average, than their White counterparts (b=3.85, p<0.01). However, rate of shortening was greater for Blacks, who showed a larger difference in length between birth and adulthood (b=5.10, p=0.01) as compared with Whites, resulting in smaller racial differences in absolute adult LTL.

Childhood Social Disadvantage, Cardiometabolic Risk, and Chronic Disease in Adulthood

Adverse social environments in early life are hypothesized to become biologically embedded during the first few years of life, with potentially far-reaching implications for health across the life course. Using prospective data from a subset of a US birth cohort, the Collaborative Perinatal Project, started in 1959-1966 (n = 566), we examined associations of social disadvantage assessed in childhood with cardiometabolic function and chronic disease status more than 40 years later (in 2005-2007). Social disadvantage was measured with an index that combined information on adverse socioeconomic and family stability factors experienced between birth and age 7 years. Cardiometabolic risk (CMR) was assessed by combining information from 8 CMR biomarkers; an index of chronic disease status was derived by assessing 8 chronic diseases. Poisson models were used to investigate associations between social disadvantage and CMR or chronic disease scores while adjusting for childhood covariates and potential pathway variables. A high level of social disadvantage was significantly associated with both higher CMR (incident rate ratio = 1.69, 95% confidence interval: 1.19, 2.39) and with a higher number of chronic diseases (incident rate ratio = 1.39, 95% confidence interval: 1.00, 1.92) in minimally adjusted models. Associations with CMR persisted even after accounting for childhood and adult covariates.

Education, Genetic Ancestry, and Blood Pressure in African Americans and Whites

OBJECTIVES We assessed the relative roles of education and genetic ancestry in predicting blood pressure (BP) within African Americans and explored the association between education and BP across racial groups. METHODS We used t tests and linear regressions to examine the associations of genetic ancestry, estimated from a genomewide set of autosomal markers, and education with BP variation among African Americans in the Family Blood Pressure Program. We also performed linear regressions in self-identified African Americans and Whites to explore the association of education with BP across racial groups. RESULTS Education, but not genetic ancestry, significantly predicted BP variation in the African American subsample (b=-0.51 mm Hg per year additional education; P=.001). Although education was inversely associated with BP in the total population, within-group analyses showed that education remained a significant predictor of BP only among the African Americans. We found a significant interaction (b=3.20; P=.006) between education and self-identified race in predicting BP. CONCLUSIONS Racial disparities in BP may be better explained by differences in education than by genetic ancestry. Future studies of ancestry and disease should include measures of the social environment.

Childhood adversity, adult neighborhood context, and cumulative biological risk for chronic diseases in adulthood.

Objective We examined the association between childhood adversity and cumulative biological risk for a variety of chronic diseases in adulthood, and whether this association varied by neighborhood affluence. Methods Data were drawn from the Chicago Community Adult Health Study (2001–2003), a cross-sectional probability sample that included interviews and blood collection (n = 550 adults). A childhood adversity score was calculated from eight items. Neighborhood affluence was defined using Census data. An index to reflect cumulative biological risk was constructed as a count of eight biomarkers above clinically established thresholds, including systolic and diastolic blood pressure, resting heart rate, C-reactive protein, waist circumference, hemoglobin A1c, and total and high-density lipoprotein cholesterol. Generalized linear models with a Poisson link function were used to estimate incident rate ratios (IRRs). Results A 1-standard-deviation increase in the childhood adversity score was associated with a 9% increase in cumulative biological risk, after adjustment for demographic and behavioral characteristics (IRR = 1.09, 95% confidence interval (CI) = 1.02–1.17). This association was modified by neighborhood affluence (IRR = 0.92, 95% CI = 0.86, 0.99). Stratified models indicated that childhood adversity was associated with elevated cumulative biological risk only among individuals who resided in low-affluence (bottom tertile) neighborhoods (IRR = 1.16, 95% CI = 1.05, 1.28); there was no association in high-affluence (top tertile) neighborhoods (IRR = 0.97, 95% CI = 0.83, 1.14). Conclusions Childhood adversity is associated with elevated cumulative biological risk in adulthood, and neighborhood affluence may buffer this association. Results demonstrate the importance of neighborhood characteristics for associations between childhood adversity and disease risk, even after accounting for adult socioeconomic status.

DNA methylation at stress-related genes is associated with exposure to early life institutionalization.

OBJECTIVES Differences in DNA methylation have been associated with early life adversity, suggesting that alterations in methylation function as one pathway through which adverse early environments are biologically embedded. This study examined associations between exposure to institutional care, quantified as the proportion of time in institutional care at specified follow-up assessment ages, and DNA methylation status in two stress-related genes: FKBP5 and SLC6A4. MATERIALS AND METHODS We analyzed data from the Bucharest Early Intervention Project, which is a prospective study in which children reared in institutional settings were randomly assigned (mean age 22 months) to either newly created foster care or care as usual (to remain in their current placement) and prospectively followed. A group of children from the same geographic area, with no history of institutionalized caregiving, were also recruited. DNA methylation status was determined in DNA extracted from buccal epithelial cells of children at age 12. RESULTS An inverse association was identified such that more time spent in institutional care was associated with lower DNA methylation at specific CpG sites within both genes. DISCUSSION These results suggest a lasting impact of early severe social deprivation on methylation patterns in these genes, and contribute to a growing literature linking early adversity and epigenetic variation in children. Am J Phys Anthropol 161:84-93, 2016..

DNA methylation of stress-related genes and LINE-1 repetitive elements across the healthy human placenta

OBJECTIVES DNA methylation is known to play a critical role in regulating development of placental morphology and physiology. The methylation of genes mediated by glucocorticoid hormones may be particularly vulnerable to intrauterine stress in the placenta. However little is known about DNA methylation of stress-related genes within a healthy placenta, and particularly whether methylation occurs uniformly across different regions of the placenta, which is a critical question for researchers seeking to analyze methylation patterns. We examined DNA methylation across four regions of the placenta to evaluate methylation levels of stress-related genes within a healthy placenta, and to evaluate whether methylation patterns vary by sampling location. STUDY DESIGN We evaluated levels of DNA methylation of three stress-related genes: NR3C1, BDNF, and 11B-HSD2 and of the repetitive element, LINE-1, in four different sample locations of 20 healthy placentas. MAIN OUTCOME MEASURES Pyrosequencing was used to quantify levels of methylation at CpG sites within the promoter regions of each of the three stress-related genes, and global methylation of LINE-1. RESULTS Very low levels of methylation were found across all three stress-related genes; no gene showed a median methylation level greater than 4.20% across placental regions. Variation in methylation between placental regions for stress-related genes and for LINE-1 was minimal. CONCLUSIONS Our data suggest that these frequently studied stress-related genes have low levels of methylation in healthy placenta tissue. Minimal variation between sites suggests that sampling location does not affect DNA methylation analyses of these genes or of LINE-1 repetitive elements.