Genetic admixture, social-behavioural factors and body composition are associated with blood pressure differently by racial-ethnic group among children

Racial/Ethnic Discrimination and Cardiometabolic Diseases: A Systematic Review

INTRODUCTION

Racial discrimination has been identified as a risk factor for cardiometabolic diseases, the leading cause of morbidity and mortality among racial/ethnic minority groups; however, there is no synthesis of current knowledge on the association between discrimination and cardiometabolic diseases. The objective of this systematic review was to summarize evidence linking racial/ethnic discrimination and cardiometabolic diseases.

METHODS

The review was conducted based on studies identified via electronic searches of 5 databases (PubMed, Google Scholar, WorldWideScience.org, ResearchGate and Microsoft Academic) using terms related to discrimination and cardiometabolic disease.

RESULTS

Of the 123 eligible studies included in the review, 87 were cross-sectional, 25 longitudinal, 8 quasi-experimental, 2 randomized controlled trials and 1 case-control. Cardiometabolic disease outcomes discussed were hypertension (n = 46), cardiovascular disease (n = 40), obesity (n = 12), diabetes (n = 11), metabolic syndrome (n = 9), and chronic kidney disease (n = 5). Although a variety of discrimination measures was employed across the studies, the Everyday Discrimination Scale was used most often (32.5%). African Americans/Blacks were the most frequently studied racial/ethnic group (53.1%), and American Indians the least (0.02%). Significant associations between racial/ethnic discrimination and cardiometabolic disease were found in 73.2% of the studies.

DISCUSSION

Racial/ethnic discrimination is positively associated with increased risk of cardiometabolic disease and higher levels of cardiometabolic biomarkers. Identifying racial/ethnic discrimination as a potential key contributor to the health inequities associated with cardiometabolic diseases is important for addressing the significant burden borne by racial/ethnic minorities.

Insulin Resistance, Serum Calcium and Hypertension: A Cross-Sectional Study of a Multiracial Population, and a Similarity Assessment of Results from a Single-Race Population's Study

BACKGROUND

Recent research suggests the need to assess more ethnic disparities in hypertension (HTN). On the other hand, studies reveal impressive mortality rates due to cardiovascular diseases for some race and ethnic groups compared to others.

METHODS

We referred to a recent study on serum calcium (SC) and insulin resistance associated with HTN incidence to compare different race groups in the latter found relationship. We compare the current study outcomes with those from the Wu et al study.

RESULTS

From 425 participants of the National Health and Nutrition Examination Survey (NHANES) data, we found a significant association between race and hypertension; Cramer's V (0.006) = 0.21 when adjusted with non-hypertensives and hypertensives. Mc Auley index (McA) was negatively related to hypertension, r (355) = -0.24, p < 0.0001. SC associated with HTN in all race groups significance persisted only in non-Hispanic Whites after multivariate adjustments R 2 of 74.1 (p = 0.03). McA was a mediator on SC-HTN in non-Hispanic Whites (NHW) (CoefIE = 13.25, [CI] = 1.42-32.13), and a moderator in other Hispanics interaction (0.04) = 0.27 and NHW interaction (0.001) = 0.028.

CONCLUSION

SC was associated with hypertension, similarly to the baseline study. SC and HTN association persisted in NHW compared to other race groups. Homeostasis model assessment (HOMA-IR) was not a mediator on SC-HTN, but with McA, this in NHW only. McA played a moderator role in OH and NHW. We suggest that race is a factor implicated in our findings, which may be investigated further in future research.

A novel indicator, childhood lipid accumulation product, is associated with hypertension in Chinese children and adolescents

Childhood hypertension has become an important public health issue. This study explored a novel indicator, namely, childhood lipid accumulation product (CLAP), which is associated with hypertension among children and adolescents. A total of 683 children and adolescents aged 8-15 years were measured for body weight, height, waist circumference (WC), abdominal skinfold thickness (AST), triacylglycerol (TG), blood pressure, dietary behaviors, and physical activity time. The novel childhood lipid accumulation product (CLAP) was the product of WC, AST, and TG (CLAP = WC (cm) × AST (mm) × TG (mmol/L)). The logarithmic CLAP (LnCLAP), height, weight, WC, WHtR, BMI, AST, and TG were standardized for sex and age using the z-score method (standardized variables: SLnCLAP, Sheight, Sweight, SWC, SWHtR, SBMI, SAST, and STG). The results showed that the overall prevalence of hypertension was 11.6% (13.1% in boys and 9.7% in girls). SLnCLAP ≥ 1, Sweight ≥ 1, SWC ≥ 1, SWHtR ≥ 1, SBMI ≥ 1, SAST ≥ 1, and STG ≥ 1 increased the statistical risk of childhood hypertension (odds ratio values (95% CI) were 3.70 (2.22-6.16), 2.58 (1.50-4.43), 3.08 (1.84-5.15), 2.33 (1.38-3.93), 2.96 (1.72-5.29), 2.38 (1.41-4.70), and 2.40 (1.38-4.19), respectively). The area under the ROC curve (AUC) for CLAP was higher than that for weight, WC, WHtR, BMI, AST, and TG in the prediction of hypertension. In conclusion, this study showed that CLAP is a novel indicator associated with hypertension in children and adolescents and can more effectively predict childhood hypertension than weight, WC, WHtR, BMI, AST, and TG can.

Genetic Loci and Novel Discrimination Measures Associated with Blood Pressure Variation in African Americans Living in Tallahassee

Sequencing of the human genome and decades of genetic association and linkage studies have dramatically improved our understanding of the etiology of many diseases. However, the multiple causes of complex diseases are still not well understood, in part because genetic and sociocultural risk factors are not typically investigated concurrently. Hypertension is a leading risk factor for cardiovascular disease and afflicts more African Americans than any other racially defined group in the US. Few genetic loci for hypertension have been replicated across populations, which may reflect population-specific differences in genetic variants and/or inattention to relevant sociocultural factors. Discrimination is a salient sociocultural risk factor for poor health and has been associated with hypertension. Here we use a biocultural approach to study blood pressure (BP) variation in African Americans living in Tallahassee, Florida by genotyping over 30,000 single nucleotide polymorphisms (SNPs) and capturing experiences of discrimination using novel measures of unfair treatment of self and others (n = 157). We perform a joint admixture and genetic association analysis for BP that prioritizes regions of the genome with African ancestry. We only report significant SNPs that were confirmed through our simulation analyses, which were performed to determine the false positive rate. We identify eight significant SNPs in five genes that were previously associated with cardiovascular diseases. When we include measures of unfair treatment and test for interactions between SNPs and unfair treatment, we identify a new class of genes involved in multiple phenotypes including psychosocial distress and mood disorders. Our results suggest that inclusion of culturally relevant stress measures, like unfair treatment in African Americans, may reveal new genes and biological pathways relevant to the etiology of hypertension, and may also improve our understanding of the complexity of gene-environment interactions that underlie complex diseases.

African Ancestry, Social Factors, and Hypertension Among Non-Hispanic Blacks in the Health and Retirement Study

The biomedical literature contains much speculation about possible genetic explanations for the large and persistent black-white disparities in hypertension, but profound social inequalities are also hypothesized to contribute to this outcome. Our goal is to evaluate whether socioeconomic status (SES) differences provide a plausible mechanism for associations between African ancestry and hypertension in a U.S. cohort of older non-Hispanic blacks. We included only non-Hispanic black participants (N = 998) from the Health and Retirement Study who provided genetic data. We estimated percent African ancestry based on 84,075 independent single nucleotide polymorphisms using ADMIXTURE V1.23, imposing K = 4 ancestral populations, and categorized into quartiles. Hypertension status was self-reported in the year 2000. We used linear probability models (adjusted for age, sex, and southern birth) to predict prevalent hypertension with African ancestry quartile, before and after accounting for a small set of SES measures. Respondents with the highest quartile of African ancestry had 8 percentage points' (RD = 0.081; 95% CI: -0.001, 0.164) higher prevalence of hypertension compared to the lowest quartile. Adjustment for childhood disadvantage, education, income, and wealth explained over one-third (RD = 0.050; 95% CI: -0.034, 0.135) of the disparity. Explanations for the residual disparity remain unspecified and may include other indicators of SES or diet, lifestyle, and psychosocial mechanisms.

Socioeconomic Position, But Not African Genomic Ancestry, Is Associated With Blood Pressure in the Bambui-Epigen (Brazil) Cohort Study of Aging

The study objective is to examine the role of African genome origin on baseline and 11-year blood pressure trajectories in community-based ethnoracially admixed older adults in Brazil. Data come from 1272 participants (aged ≥60 years) of the Bambui cohort study of aging during 11 years of follow-up. Outcome measures were systolic blood pressure, diastolic blood pressure, and hypertension control. Potential confounding variables were demographic characteristics, socioeconomic position (schooling and household income), and health indicators (smoking, sedentary lifestyle, high-density lipoprotein cholesterol, waist circumference, diabetes mellitus, and cardiovascular diseases), including antihypertensive drug use. We used 370 539 single-nucleotide polymorphisms to estimate each individual's African, European, and Native American trihybrid ancestry proportions. Median African, European, and Native American ancestry were 9.6%, 84.0%, and 5.3%, respectively. Among those with African ancestry, 59.4% came from East and 40.6% from West Africa. Baseline systolic and diastolic blood pressure, controlled hypertension, and their respective trajectories, were not significantly (P>0.05) associated with level (in quintiles) of African genomic ancestry. Similar results were found for West and East African subcontinental origins. Lower schooling level (<4 years versus higher) showed a significant and positive association with systolic blood pressure (Adjusted β=2.92; 95% confidence interval, 0.85-4.99). Lower monthly household income per capita (<USD 180.00 versus higher) showed an inverse association with hypertension control (β=-0.35; 95% confidence interval, -0.63 to -0.08, respectively). Our results support the view that favors social and environmental factors as determinants of blood pressure and hypertension control.

The role of racial genetic admixture with endometrial cancer outcomes: An NRG Oncology/Gynecologic Oncology Group study

PURPOSE

Racial genetic admixture (RGA), a measure to account for ancestral genetic background that correlates with individual's racial classification, could provide insights on causation of racial disparity in endometrial cancer (EC). Our objective is to evaluate the association of RGA with EC outcomes.

METHODS

EC patients enrolled onto the GOG-210 protocol were eligible. A randomized subcohort stratified by stage and self-reported race/ethnicity of black or white was used. Genotyping was performed using custom-selected Ancestry Informative Markers to calculate individual admixture estimates of African and European ancestral background.

RESULTS

A total of 149 patients were evaluated (self-reported race: 70 black & 79 white). Mean RGA for African ancestry for self-reported black patients was 0.65 (range 0.04-0.86); while mean RGA for European ancestry for self-reported white patients was 0.77 (range 0.12-0.88). Progression-free survival (PFS) analysis using proportional hazards models stratified by stage and race revealed that each 0.10 increase in African ancestry was associated with worse PFS with hazard ratio (HR) of 1.11 (95% CI 0.90-1.37). Each 0.10 increase in European RGA was associated with improved PFS with HR of 0.86 (95% CI 0.69-1.07). Using tertiles of African RGA showed increasing risk of progression of death with increasing African RGA (with 0-5% as reference), HR (95% CIs) for top two tertiles are: 6%-66%: 1.38 (0.64, 2.97), and 67%-86%: 2.27 (0.74, 6.95).

CONCLUSION

RGA demonstrated a trend with PFS in self-reported black and white patients with EC. Patients with increased levels of African ancestry showed a trend towards worse survival after stratifying by stage/race.

Common variants in the LAMA5 gene associate with fasting plasma glucose and serum triglyceride levels in a cohort of pre-and early pubertal children

Laminins are large glycoproteins found in basement membranes where they play a vital role in tissue architecture and cell behavior. Previously, we reported the association of two LAMA5 polymorphisms (rs659822 and rs944895) with anthropometric traits, fasting lipid profile, and plasma glucose levels in pre-menopausal women and elderly subjects. Furthermore, earlier work in mice showed that Lama5 is involved in organogenesis and placental function during pregnancy. The objective of this study was to investigate whether LAMA5 rs659822 or rs944895 are associated with inter-individual variability in birth weight as well as anthropometric, fasting lipid profile, and fasting glucose levels in children. Two hundred and eighty nine healthy children aged 7-12 years of European, Hispanic, and African-American ancestry were studied. Co-dominant models adjusted for genetic admixture, age, gender, and stages of puberty were used to test for the association of the polymorphisms with each trait. Our analysis showed significant associations of rs659822 with fasting plasma glucose levels (p = 0.0004) and of rs944895 with fasting serum triglycerides (p = 0.004) after Bonferroni correction for multiple testing. Our results corroborate our previous findings that genetic variants in LAMA5 contribute to variation in metabolic phenotypes and provide evidence that this may occur early in life.

Associations SELE gene haplotype variant and hypertension in Mongolian and Han populations

Genetic variation is thought to contribute to the etiology of hypertension, and E-selectin is a candidate essential hypertension-associated gene.

OBJECTIVE

In this study, we attempted to test the hypothesis that subtle haplotype variants of SELE genes may be sources of essential hypertension in Mongolian and Han populations.

MATERIALS

A total of 429 unrelated Mongolian herdsmen and 416 Han farmers were enrolled, including 212 Mongolian essential hypertension (EH) patients, 217 Mongolian normotensives (controls), 200 Han EH patients and 216 Han normotensives (controls).

METHODS

All nine tag single-nucleotide polymorphisms (SNPs) within the SELE gene were retrieved from HapMap and the genotyping was performed using a polymerase chain reaction (PCR)/ligase detection reaction assay. Results The distributions of the A-allele frequency of rs3917458 and the C-allele frequency of rs2179172 differed significantly between the hypertensive subjects and controls in the Han population. The frequency of haplotype GGC was significantly higher in the EH group than in the controls in the Mongolian population. In the Han population, a significant difference was observed in the haplotype frequency of TCC between the patients and controls, whereas haplotype ACA was detected significantly less often in the EH subjects than in the controls.

CONCLUSION

Meanwhile, the haplotype TCC in the Han hypertensive patients and the haplotype GGC in the Mongolian patients had independent effects in increasing the risk for EH and maybe used as risk factors for predicting high blood pressure. However, the haplotype ACA had an independent effect in decreasing the risk of hypertension and may be protective in normotensive subjects in the Han population. Therefore, multiple SNPs in combination in SELE may confer a risk of hypertension.

Perceived racial discrimination and hypertension: a comprehensive systematic review

OBJECTIVE

Discrimination is posited to underlie racial disparities in hypertension. Extant literature suggests a possible association between racial discrimination and blood pressure, although inconsistent findings have been reported. The aim of this comprehensive systematic review was to quantitatively evaluate the association between perceived racial discrimination with hypertensive status and systolic, diastolic, and ambulatory blood pressure.

METHOD

Electronic database search of PubMed and PsycINFO (keywords: blood pressure/hypertension/diastolic/systolic, racism/discrimination/prejudice/unfair treatment) was combined with descendancy and ascendancy approaches. Forty-four articles (N = 32,651) met inclusion criteria. Articles were coded for demographics, hypertensive diagnosis, blood pressure measurement, discrimination measure and constructs, study quality, and effect sizes.

RESULTS

Random effects meta-analytic models were tested based on Fisher's Z, the derived common effect size metric. Overall, perceived racial discrimination was associated with hypertensive status, Zhypertension = 0.048, 95% CI [.013, .087], but not with resting blood pressure, Zsystolic = 0.011, 95% CI [-.006, .031], Zdiastolic = .016, 95% CI [-.006, .034]. Moderators that strengthened the relation included sex (male), race (Black), age (older), education (lower), and hypertensive status. Perceived discrimination was most strongly associated with nighttime ambulatory blood pressure, especially among Blacks.

CONCLUSIONS

Despite methodological limitations in the existing literature, there was a small, significant association between perceived discrimination and hypertension. Future studies should consider ambulatory nighttime blood pressure, which may more accurately capture daily variation attributable to experienced racial discrimination. Perceived discrimination may partly explain racial health disparities.

Self-Reported Experiences of Discrimination and Cardiovascular Disease

Researchers have long speculated that exposure to discrimination may increase cardiovascular disease (CVD) risk but compared to other psychosocial risk factors, large-scale epidemiologic and community based studies examining associations between reports of discrimination and CVD risk have only emerged fairly recently. This review summarizes findings from studies of self-reported experiences of discrimination and CVD risk published between 2011-2013. We document the innovative advances in recent work, the notable heterogeneity in these studies, and the considerable need for additional work with objective clinical endpoints other than blood pressure. Implications for the study of racial disparities in CVD and clinical practice are also discussed.

Genetic factors in exercise adoption, adherence and obesity

Physical activity and exercise play critical roles in energy balance. While many interventions targeted at increasing physical activity have demonstrated efficacy in promoting weight loss or maintenance in the short term, long term adherence to such programmes is not frequently observed. Numerous factors have been examined for their ability to predict and/or influence physical activity and exercise adherence. Although physical activity has been demonstrated to have a strong genetic component in both animals and humans, few studies have examined the association between genetic variation and exercise adherence. In this review, we provide a detailed overview of the non-genetic and genetic predictors of physical activity and adherence to exercise. In addition, we report the results of analysis of 26 single nucleotide polymorphisms in six candidate genes examined for association to exercise adherence, duration, intensity and total exercise dose in young adults from the Training Interventions and Genetics of Exercise Response (TIGER) Study. Based on both animal and human research, neural signalling and pleasure/reward systems in the brain may drive in large part the propensity to be physically active and to adhere to an exercise programme. Adherence/compliance research in other fields may inform future investigation of the genetics of exercise adherence.

Racial/Ethnic Variability in Hypertension Prevalence and Risk Factors in National Health Interview Survey

Objective. Hypertension is one of the leading causes of death attributed to cardiovascular diseases, and the prevalence varies across racial/ethnic groups, with African Americans being disproportionately affected. The underlying causes of these disparities are not fully understood despite volume of literature in this perspective. We aimed in this current study to examine ethnic/racial disparities in hypertension utilizing Hispanics as the base racial/ethnic group for comparison. Research Design and Methods. We utilized the National Health Interview Survey (NHIS), which is a large cross-sectional survey of the United States non-institutionalized residents to investigate the racial/ethnic disparities in hypertension after the adjustment of other socio-economic, demographic, and prognostic risk factors. The study participants were adults (n = 30,852). Data were analyzed using Chi square statistic, and logistic regression model. Results. There were statistically significant differences by race/ethnicity with respect to income, education, marital status, smoking, alcohol, physical activities, body mass index, and age, P < 0.01, but not insurance coverage, P > 0.01. Hispanic ethnicity (18.9%) compared to either non-Hispanic white (27.7%) or non-Hispanic black (35.5%) was associated with the lowest prevalence of hypertension. Race/ethnicity was a single independent predictor of hypertension, with non-Hispanic black more likely to be hypertensive compare with Hispanic, prevalence odds ratio (POR), 2.38, 99% Confidence Interval (CI), 2.17–2.61 and non-Hispanic white, POR, 1.64, 99% CI, 1.52–1.77. After controlling for the confounding variables, the racial/ethnic differences in hypertension persisted. Conclusions. Racial/ethnic disparities in hypertension persisted after controlling for potential predictors of hypertension in NHIS, implying the inability of known hypertension risk factors to account for racial/ethnic variability in hypertension in US.

Socioeconomic status and lung cancer: unraveling the contribution of genetic admixture

OBJECTIVES

We examined the relationship between genetic ancestry, socioeconomic status (SES), and lung cancer among African Americans and Latinos.

METHODS

We evaluated SES and genetic ancestry in a Northern California lung cancer case-control study (1998-2003) of African Americans and Latinos. Lung cancer case and control participants were frequency matched on age, gender, and race/ethnicity. We assessed case-control differences in individual admixture proportions using the 2-sample t test and analysis of covariance. Logistic regression models examined associations among genetic ancestry, socioeconomic characteristics, and lung cancer.

RESULTS

Decreased Amerindian ancestry was associated with higher education among Latino control participants and greater African ancestry was associated with decreased education among African lung cancer case participants. Education was associated with lung cancer among both Latinos and African Americans, independent of smoking, ancestry, age, and gender. Genetic ancestry was not associated with lung cancer among African Americans.

CONCLUSIONS

Findings suggest that socioeconomic factors may have a greater impact than genetic ancestry on lung cancer among African Americans. The genetic heterogeneity and recent dynamic migration and acculturation of Latinos complicate recruitment; thus, epidemiological analyses and findings should be interpreted cautiously.

Ethnic and socioeconomic influences on childhood blood pressure: the Child Heart and Health Study in England

OBJECTIVES

Compared to UK white European adults, UK black African-Caribbean adults have higher mean SBP and DBP; UK South Asian adults have higher mean DBP but lower SBP. Information on blood pressure (BP) in UK children from different ethnic groups is limited. The aim of this study was to compare BP levels in UK children of black African-Caribbean, South Asian and white European origin.

METHODS

BP and body build were measured in 5666 children in a cross-sectional study of UK primary school children of South Asian, black African-Caribbean and white European origin aged 9-10 years. Ethnic and socioeconomic differences in BP were obtained from multilevel linear regression models.

RESULTS

After adjustment for height and adiposity, black African-Caribbean children had lower mean SBP than white Europeans [difference 1.62  mmHg, 95% confidence interval (CI) 0.86-2.38  mmHg], whereas mean DBP was similar (difference 0.58  mmHg, 95% CI -0.12 to 1.28  mmHg). The lower SBP was particularly marked in black African rather than Caribbean children (P  =  0.002). South Asian children had lower mean SBP (difference 1.10  mmHg, 95% CI 0.34-1.86  mmHg) than white Europeans and higher mean DBP (difference 1.07  mmHg, 95% CI 0.37-1.76  mmHg). The higher mean DBP was particularly marked among Indian and Bangladeshi, rather than Pakistani, children (P  =  0.01). BP was unrelated to socioeconomic circumstances; ethnic differences in BP were not affected by socioeconomic adjustment.

CONCLUSION

A BP pattern similar to that in adults is present in UK South Asian but not in UK black African-Caribbean children at 9-10 years.

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.

Association of ATP1B1, RGS5 and SELE polymorphisms with hypertension and blood pressure in African-Americans

OBJECTIVE

Although an increasing number of hypertension-associated genetic variants is being reported, replication of these findings in independent studies has been challenging. Several genes in a human chromosome 1q linkage region have been reported to be associated with hypertension. We examined polymorphisms in three of these genes (ATP1B1, RGS5 and SELE) in relation to hypertension and blood pressure in a cohort of African-Americans.

METHODS

We genotyped 87 single nucleotide polymorphisms (SNPs) from the ATP1B1, RGS5 and SELE genes in a well characterized cohort of 968 African-Americans and performed a case-control study to identify susceptibility alleles for hypertension and blood pressure regulation. Single SNP and haplotype association testing was done under an additive genetic model with adjustment for age, sex, BMI and ancestry-by-genotype (principal components).

RESULTS

A total of 12 SNPs showed nominal association with hypertension and/or blood pressure. The strongest signal for hypertension was for rs2815272 in the RGS5 gene (P = 9.3 × 10). For SBP, rs3917420 in the SELE gene (P = 9.0 × 10) and rs4657251 in the RGS5 gene (P = 9.7 × 10) were the top hits. Effect size for each of these variants was approximately 2-3 mmHg. A five-SNP haplotype in the SELE gene also showed significant association with SBP after correction for multiple testing (P < 0.01).

CONCLUSION

These findings provide additional support for the genetic role of ATP1B1, RGS5 and SELE in hypertension and blood pressure regulation.