Race, ethnicity and social class and the complex etiologies of asthma

Trends in US Pediatric Asthma Hospitalizations, by Race and Ethnicity, 2012-2020

Introduction

Some racial and ethnic minority communities have long faced a higher asthma burden than non-Hispanic White communities. Prior research on racial and ethnic pediatric asthma disparities found stable or increasing disparities, but more recent data allow for updated analysis of these trends.

Methods

Using 2012-2020 National Inpatient Sample data, we estimated the number of pediatric asthma hospitalizations by sex, age, and race and ethnicity. We converted these estimates into rates using data from the US Census Bureau and then conducted meta-regression to assess changes over time. Because the analysis spanned a 2015 change in diagnostic coding, we performed separate analyses for periods before and after the change. We also excluded 2020 data from the regression analysis.

Results

The number of pediatric asthma hospitalizations decreased over the analysis period. Non-Hispanic Black children had the highest prevalence (range, 9.8-36.7 hospitalizations per 10,000 children), whereas prevalence was lowest among non-Hispanic White children (range, 2.2-9.4 hospitalizations per 10,000 children). Although some evidence suggests that race-specific trends varied modestly across groups, results overall were consistent with a similar rate of decrease across all groups (2012-2015, slope = -0.83 [95% CI, -1.14 to -0.52]; 2016-2019, slope = -0.35 [95% CI, -0.58 to -0.12]).

Conclusion

Non-Hispanic Black children remain disproportionately burdened by asthma-related hospitalizations. Although the prevalence of asthma hospitalization is decreasing among all racial and ethnic groups, the rates of decline are similar across groups. Therefore, previously identified disparities persist. Interventions that consider the specific needs of members of disproportionately affected groups may reduce these disparities.

Understanding the determinants of self-reported asthma in Turkey: insights from national data on individual, lifestyle, socioeconomic, and healthcare access factors

Asthma, influenced by genetic, environmental, and social factors is leading to poor outcomes and preventable mortality due to inadequate care and limited access to effective treatments. This study aimed to analyze self-reported asthma prevalence in Turkey, focusing on its determinants, such as individual factors, lifestyle, socioeconomic status, and healthcare access.This study conducts a secondary analysis of the 2019 Turkiye Health Survey (THS), employing a nationally representative cross-sectional design by the Turkish Statistical Institute. The sampling utilized a stratified, two-stage cluster sampling method, with data from 16,976 adults (aged 15 years and older) analyzed for asthma determinants. The independent variables are categorized into four domains: individual factors, lifestyle assessment, socioeconomic factors, and access to the healthcare services.The prevalence of asthma is 9.8%, varying significantly across demographics. Higher asthma rates are observed among older, divorced/widowed individuals, those with communication difficulties, and obese individuals. Cost-related unmet healthcare needs and appointment scheduling delays increase asthma risk. Logistic regression models identified age, marital status, obesity, education level, and healthcare access as significant predictors of asthma.This study underscores the multifaceted determinants of asthma in Turkey, highlighting the necessity for targeted interventions addressing individual, lifestyle, socioeconomic, and healthcare access factors.

The association between waist circumference and adult asthma attack using nationally representative samples

AIMS

This study aims to explore the relationship between waist circumference and asthma attack in adults.

METHODS

In this cross-sectional study, we analysed data from 5,530 U.S. adults diagnosed with asthma. Participants were categorized into two groups based on their experience of asthma attacks: with or without asthma attacks. We employed adjusted weighted logistic regression models, weighted restricted cubic splines, subgroup and sensitivity analyses to assess the association between waist circumference and asthma attack.

RESULTS

The median age of all participants was 43 years, and the median waist circumference was 98.9 cm, with a median BMI was 28.50 kg/m2. Participants in the asthma attack group had significantly higher waist circumferences than those in the non-attack group (P < 0.001). After full adjustment for body mass index-defined obesity, age, gender, race, education levels, poverty income ratio levels, smoking status, and metabolic syndrome, every 5 cm increase in waist circumference exhibited a 1.06 times higher likelihood of asthma attack probability. The weighted restricted cubic spline analysis demonstrated an increased risk of asthma attacks with rising waist circumference. Subgroup analyses confirmed this relationship across various groups differentiated by gender, age, and smoking status. When applying a stricter definition of asthma attack, the weighted logistic regression models showed robust association between waist circumference and asthma attack.

CONCLUSION

Waist circumference is an independent predictor of asthma attacks. Our findings underscore the importance of waist circumference measurement in evaluating the risk of asthma attacks.

Diversity, Equity, and Inclusion: A Decade of Progress?

The concepts of diversity, equity, and inclusion are fundamental and more recently heavily discussed within medicine, research, and the larger society. There is increasing awareness that diversity of thoughts, perspectives, and backgrounds yields stronger teams and more effective results. There is also increasing awareness that stark inequities from systemic, institutional, and individual levels exist that limit the baseline opportunities for many populations. To close disparity gaps, broad aspects of diversity and promoting equity are required and efforts must be inclusive of those most marginalized. In this Clinical Commentary, we discuss, "How and If progress has been made in Diversity, Equity, Inclusion within the field of Allergy/Asthma/Immunology in the past decade?" We discuss the current state of clinical practice and what has been revealed over the past 10 years; describe our current workforce and what progress has or has not occurred there; and finally, review the state of scientific and medical research.

Risk Factors of Childhood Asthma Among Patients Attending a Tertiary Care Centre in North-East India

Introduction

Asthma is a chronic lung illness marked by a reversible airway blockage. Both genetic and environmental factors influence higher asthma rates. The present study aims to assess the various socio-demographic and environmental factors influencing the causation of childhood asthma among patients attending the Paediatric Department of Gauhati Medical College and Hospital (GMCH), Assam.

Materials and Methods

A total of 150 clinically diagnosed asthma patients of 3–12 years as cases and patients of the same age group free from respiratory diseases with no history of asthma in a 1:1 ratio as controls were selected. A predesigned and pretested proforma was used to collect data, and written informed consent was obtained from all the legal guardians of the participants. Data were analyzed by chi-square test and binary logistic regression using SPSS V20, considering a p-value <0.05 significant.

Results

Urban and male children were found to be at higher risk of developing asthma. Children belonging to the urban locality (OR= 4.53; 95% CI: 1.57–13.09; p<0.05), damp environment (OR= 5.21; 95% CI: 1.23–22.10; p<0.05), lower socioeconomic status (OR= 3.48; 95% CI: 1.34–9.01; p<0.05), presence of pets (OR= 6.77; 95% CI: 1.76–25.99; p<0.05), family history of atopy/ allergy (OR= 43.29; 95% CI: 5.80–323.15 p<0.05), smoking/passive smoking (OR=23.54; 95% CI: 1.41–394.21 p<0.05) and mixed feeding (OR= 4.47; 95% CI: 1.46–13.63 p<0.05) were the significant risk factors of childhood asthma.

Conclusion

Children are vulnerable to environmental-induced asthma. Awareness and preventive measures are necessary to control and reduce the burden of childhood asthma.

LTA4H rs2660845 association with montelukast response in early and late-onset asthma

Leukotrienes play a central pathophysiological role in both paediatric and adult asthma. However, 35% to 78% of asthmatics do not respond to leukotriene inhibitors. In this study we tested the role of the LTA4H regulatory variant rs2660845 and age of asthma onset in response to montelukast in ethnically diverse populations. We identified and genotyped 3,594 asthma patients treated with montelukast (2,514 late-onset and 1,080 early-onset) from seven cohorts (UKBiobank, GoSHARE, BREATHE, Tayside RCT, PAGES, GALA II and SAGE). Individuals under montelukast treatment experiencing at least one exacerbation in a 12-month period were compared against individuals with no exacerbation, using logistic regression for each cohort and meta-analysis. While no significant association was found with European late-onset subjects, a meta-analysis of 523 early-onset individuals from European ancestry demonstrated the odds of experiencing asthma exacerbations by carriers of at least one G allele, despite montelukast treatment, were increased (odds-ratio = 2.92, 95%confidence interval (CI): 1.04-8.18, I2 = 62%, p = 0.0412) compared to those in the AA group. When meta-analysing with other ethnic groups, no significant increased risk of asthma exacerbations was found (OR = 1.60, 95% CI: 0.61-4.19, I2 = 85%, p = 0.342). Our study demonstrates that genetic variation in LTA4H, together with timing of asthma onset, may contribute to variability in montelukast response. European individuals with early-onset (≤18y) carrying at least one copy of rs2660845 have increased odd of exacerbation under montelukast treatment, presumably due to the up-regulation of LTA4H activity. These findings support a precision medicine approach for the treatment of asthma with montelukast.

Leveraging genetic ancestry to study health disparities

Research to understand human genomic variation and its implications in health has great potential to contribute in the reduction of health disparities. Biological anthropology can play important roles in genomics and health disparities research using a biocultural approach. This paper argues that racial/ethnic categories should not be used as a surrogate for sociocultural factors or global genomic clusters in biomedical research or clinical settings, because of the high genetic heterogeneity that exists within traditional racial/ethnic groups. Genetic ancestry is used to show variation in ancestral genomic contributions to recently admixed populations in the United States, such as African Americans and Hispanic/Latino Americans. Genetic ancestry estimates are also used to examine the relationship between ancestry-related biological and sociocultural factors affecting health disparities. To localize areas of genomes that contribute to health disparities, admixture mapping and genome-wide association studies (GWAS) are often used. Recent GWAS have identified many genetic variants that are highly differentiated among human populations that are associated with disease risk. Some of these are population-specific variants. Many of these variants may impact disease risk and help explain a portion of the difference in disease burden among racial/ethnic groups. Genetic ancestry is also of particular interest in precision medicine and disparities in drug efficacy and outcomes. By using genetic ancestry, we can learn about potential biological differences that may contribute to the heterogeneity observed across self-reported racial groups.

Transethnic associations among immune-mediated diseases and single-nucleotide polymorphisms of the aryl hydrocarbon response gene ARNT and the PTPN22 immune regulatory gene

BACKGROUND

Because immune responses are sensitive to environmental changes that drive selection of genetic variants, we hypothesized that polymorphisms of some xenobiotic response and immune response genes may be associated with specific types of immune-mediated diseases (IMD), while others may be associated with IMD as a larger category regardless of specific phenotype or ethnicity.

OBJECTIVE

To examine transethnic gene-IMD associations for single nucleotide polymorphism (SNP) frequencies of prototypic xenobiotic response genes-aryl hydrocarbon receptor (AHR), AHR nuclear translocator (ARNT), AHR repressor (AHRR) - and a prototypic immune response gene, protein tyrosine phosphatase, non-receptor type 22 (PTPN22), in subjects from the Environmental Polymorphisms Registry (EPR).

METHODS

Subjects (n = 3731) were genotyped for 14 SNPs associated with functional variants of the AHR, ARNT, AHRR, and PTPN22 genes, and their frequencies were compared among African Americans (n = 1562), Caucasians (n = 1838), and Hispanics (n = 331) with previously reported data. Of those genotyped, 2015 EPR subjects completed a Health and Exposure survey. SNPs were assessed via PLINK for associations with IMD, which included those with autoimmune diseases, allergic disorders, asthma, or idiopathic pulmonary fibrosis. Transethnic meta-analyses were performed using METAL and MANTRA approaches.

RESULTS

ARNT SNP rs11204735 was significantly associated with autoimmune disease by transethnic meta-analyses using METAL (odds ratio, OR [95% confidence interval] = 1.29 [1.08-1.55]) and MANTRA (ORs ranged from 1.29 to 1.30), whereas ARNT SNP rs1889740 showed a significant association with autoimmune disease by METAL (OR = 1.25 [1.06-1.47]). For Caucasian females, PTPN22 SNP rs2476601 was significantly associated with autoimmune disease by allelic association tests (OR = 1.99, [1.30-3.04]). In Caucasians and Caucasian males, PTPN22 SNP rs3811021 was significantly associated with IMD (OR = 1.39 [1.12-1.72] and 1.50 [1.12-2.02], respectively) and allergic disease (OR = 1.39 [1.12-1.71], and 1.62 [1.19-2.20], respectively). In the transethnic meta-analysis, PTPN22 SNP rs3811021 was significantly implicated in IMD by METAL (OR = 1.31 [1.10-1.56]), and both METAL and MANTRA suggested that rs3811021 was associated with IMD and allergic disease in males across all three ethnic groups (IMD METAL OR = 1.50 [1.15-1.95]; IMD MANTRA ORs ranged from 1.47 to 1.50; allergic disease METAL OR = 1.58 [1.20-2.08]; allergic disease MANTRA ORs ranged from 1.55 to 1.59).

CONCLUSIONS

Some xenobiotic and immune response gene polymorphisms were shown here, for the first time, to have associations across a broad spectrum of IMD and ethnicities. Our findings also suggest a role for ARNT in the development of autoimmune diseases, implicating environmental factors metabolized by this pathway in pathogenesis. Further studies are needed to confirm these data, assess the implications of these findings, define gene-environment interactions, and explore the mechanisms leading to these increasingly prevalent disorders.

Depressive Symptoms Increase the Risk of Mortality for White but Not Black Older Adults

Introduction. Long-term studies have shown that depressive symptoms predict the risk of mortality. However, it is unknown if this effect is present in shorter time intervals. In addition, recent research suggests that the salience of the negative affect on the risk of mortality is not similar across racial groups. The current study uses data from a national study of Black and White older adults to examine racial differences in the effect of baseline depressive symptoms on mortality risk over three years in the United States. Methods. This study used a longitudinal prospective design and followed 1493 older adults who were either White (n = 759) or Black (n = 734) for three years from 2001 to 2004. Depressive symptoms measured at baseline was the independent variable. Demographic factors, socio-economic characteristics (education, income, marital status), health behaviors (smoking and drinking), and health (self-rated health) measured at baseline in 2001 were covariates. The dependent variable was all-cause mortality between 2001 and 2004. Race was the moderator. Logistic regressions were used for data analysis. Results. In the pooled sample, high depressive symptoms at baseline were not associated with the three-year risk of mortality. In the pooled sample, we found a significant interaction between race and depressive symptoms on mortality, suggesting a stronger effect for Whites in comparison to Blacks. In race stratified models, depressive symptoms at baseline were predictive of mortality risk for Whites, but not Blacks. Conclusions. In the United States, Black-White differences exist in the effects of depressive symptoms on mortality risk in older adults. White older adults may be more vulnerable to the effects of depressive symptoms on mortality risk.

Sociodemographic Factors Mediate Race and Ethnicity-associated Childhood Asthma Health Disparities: a Longitudinal Analysis

BACKGROUND

Race and ethnicity-based disparities in childhood asthma are well established. We characterized the longitudinal effects associated with being African-American/Black or Hispanic/Latino on a range of asthma outcomes, and the extent to which sociodemographic factors, caregiver health literacy, education level, and asthma knowledge mediate these associations.

METHODS

Children ages 8-15 and their caregivers (n = 544) in the Chicago Initiative to Raise Asthma Health Equity (CHIRAH) cohort completed interviews every 3 months for 1.5 years. Health literacy was measured with the Rapid Estimate of Adult Literacy in Medicine (REALM). Other covariates include sex, age, education level, income, smoke exposure, asthma duration, employment status, and insurance status. We conducted a series of models to evaluate these factors as mediators of the relationship between race/ethnicity and (1) asthma knowledge, (2) asthma-related quality of life, (3) asthma severity, and (4) asthma control based on NAEPP/EPR-3 2007 guidelines.

RESULTS

African-American race and Hispanic/Latino ethnicity were significantly associated with all outcomes when compared to Whites. Adjusting for sociodemographic factors resulted in the most significant mediation of racial/ethnic disparities in all outcomes. Health literacy was a partial mediator of race/ethnic disparities in asthma knowledge and asthma-related quality of life. Asthma knowledge remained significantly associated with race and ethnicity, and race remained associated with asthma-related quality of life.

CONCLUSIONS

African-American race and Hispanic/Latino ethnicity are significantly associated with worse asthma compared to Whites in longitudinal analyses. Sociodemographic factors are potent mediators of these disparities, and should be considered when designing interventions to reduce asthma disparities. Health literacy and education level are partial mediators.

Income Gradient in Renal Disease Mortality in the United States

Background

Non-communicable diseases and associated mortality follow a social gradient and chronic kidney disease is not an exception to this rule. Intermediate behavioral and medical factors that may explain such social gradients are, however, still unknown.

Objectives

Using nationally representative data in the United States, this study was conducted to investigate the mediating effect of medical and behavioral risk factors on the association between socioeconomic status (SES) and renal disease mortality.

Patients and methods

Americans’ Changing Lives Study (ACL), 1986–2011, is a 25-year nationally representative prospective cohort study. ACL followed 3,361 adults for up to 25 years. Income, education, and unemployment were the main predictors of interest. Death due to renal disease was the main outcome. Health behaviors (smoking, drinking, and exercise) and medical risk factors (diabetes, hypertension, and obesity) were the mediators. Cox proportional hazards models were used for data analysis.

Results

Higher income (HR = 0.75; 95% CI = 0.62–0.89) was associated with lower risk of death due to renal disease over the 25-year follow-up period. Although health behaviors and medical risk factors at baseline were also predictors of the outcome, they failed to explain the effect of income on death due to renal disease. That is, income was associated with death due to renal disease above and beyond all potential mediators including behavioral and medical risk factors.

Conclusion

Socioeconomic inequalities in the United States cause disparities in renal disease mortality; however, such differences are not due to health behaviors (smoking and drinking) and medical risk factors (hypertension and diabetes). To reduce disparities in renal disease mortality in the United States, policies should go beyond health behaviors and medical risk factors. While programs should help low-income individuals maintain exercise and avoid smoking, reduction of income disparities should be regarded as a strategy for reduction of disparities in renal disease mortality. By increasing minimum pay and minimizing the income gap, we may reduce disparities in renal disease mortality.

Race, sense of control over life, and short-term risk of mortality among older adults in the United States

INTRODUCTION

Sense of control over life has been shown to have protective health effects in studies that have mostly enrolled White middle class individuals. It is unknown, however, whether populations differ in the protective health gain associated with sense of control over life. This study compared a nationally representative sample of Black and White older adults for protective effects of sense of control over life on short-term risk of all-cause mortality in the United States.

MATERIAL AND METHODS

This longitudinal prospective study followed 1,493 White (n = 759) and Black (n = 734) older adults (age 66 or more) from 2001 to 2004. Race, demographics, socio-economics, sense of control over life, health behaviors, and self-rated health were measured at baseline in 2001. Outcome was all-cause mortality occurring between 2001 and 2004. Logistic regression models were used for data analysis.

RESULTS

In the pooled sample, sense of control over life was protective against 3-year mortality risk above and beyond demographics, socio-economics, health behaviors, and self-rated health. We found a race by sense of control over life interaction, suggesting a stronger protective effect of control over life on mortality risk for Whites compared to Blacks. In race-specific models, sense of control over life at baseline was predictive of mortality among Whites but not Blacks.

CONCLUSIONS

In the United States, Black older adults do not gain a survival benefit associated with high levels of sense of control over life, as do their White counterparts. It is not clear why sense of control over life translates into survival for Whites but not for Blacks.

Diabetes, hypertension, obesity, and long-term risk of renal disease mortality: Racial and socioeconomic differences

AIMS/INTRODUCTION

Diabetes, hypertension, and obesity increase the risk of chronic kidney disease and associated mortality. Race and socioeconomic status (SES) differences in the effects of these risk factors are, however, still unknown. The current study aimed to investigate whether or not race and SES alter the effects of diabetes, hypertension, and obesity on mortality due to renal disease.

MATERIALS AND METHODS

Data came from the Americans' Changing Lives Study, 1986-2011, a nationally representative prospective cohort of adults with 25 years of follow up. The study included 3,361 adults aged 25 years and older who were followed for up to 25 years. The outcome was death from renal disease. Diabetes, hypertension, and obesity were the main predictors. Race and SES (education, income, and employment) were moderators. Health behaviors and health status at baseline were covariates. We used Cox proportional hazards models for data analysis.

RESULTS

In separate models, diabetes, hypertension, and obesity at baseline were associated with a higher risk of death from renal disease. From our SES indicators, education and income interacted with diabetes, hypertension, and obesity on death from renal disease. In a consistent pattern, diabetes, hypertension, and obesity showed stronger effects on the risk of death from renal disease among high-SES groups compared with low-SES individuals. Race and employment did not alter the effects of diabetes, hypertension and obesity on the risk of death from renal disease.

CONCLUSIONS

Social groups differ in how diabetes, hypertension, and obesity influence health outcomes over long-term periods. Elimination of disparities in renal disease mortality in the USA requires understanding of the complex and non-linear effects of socioeconomic and medical risk factors on health outcomes. Multidisciplinary programs and policies are required to reduce social inequality in renal disease burden caused by diabetes, hypertension, and obesity.

Perceived Discrimination Associated With Asthma and Related Outcomes in Minority Youth: The GALA II and SAGE II Studies

BACKGROUND

Asthma disproportionately affects minority populations and is associated with psychosocial stress such as racial/ethnic discrimination. We aimed to examine the association of perceived discrimination with asthma and poor asthma control in African American and Latino youth.

METHODS

We included African American (n = 954), Mexican American (n = 1,086), other Latino (n = 522), and Puerto Rican Islander (n = 1,025) youth aged 8 to 21 years from the Genes-Environments and Admixture in Latino Americans study and the Study of African Americans, Asthma, Genes, and Environments. Asthma was defined by physician diagnosis, and asthma control was defined based on the National Heart, Lung, and Blood Institute guidelines. Perceived racial/ethnic discrimination was assessed by the Experiences of Discrimination questionnaire, with a focus on school, medical, and public settings. We examined the associations of perceived discrimination with each outcome and whether socioeconomic status (SES) and global African ancestry modified these associations.

RESULTS

African American children reporting any discrimination had a 78% greater odds of experiencing asthma (OR, 1.78; 95% CI, 1.33-2.39) than did those not reporting discrimination. Similarly, African American children faced increased odds of poor asthma control with any experience of discrimination (OR, 1.97; 95% CI, 1.42-2.76) over their counterparts not reporting discrimination. These associations were not observed among Latino children. We observed heterogeneity of the association between reports of discrimination and asthma according to SES, with reports of discrimination increasing the odds of having asthma among low-SES Mexican American youth (interaction P = .01) and among high-SES other Latino youth (interaction P = .04).

CONCLUSIONS

Perceived discrimination is associated with increased odds of asthma and poorer control among African American youth. SES exacerbates the effect of perceived discrimination on having asthma among Mexican American and other Latino youth.

General Self-Efficacy and Mortality in the USA; Racial Differences

PURPOSE

General self-efficacy has been historically assumed to have universal health implications. However, less is known about population differences in long-term health effects of general self-efficacy across diverse populations. This study compared black and white American adults for (1) the association between psychosocial and health factors and general self-efficacy at baseline, and (2) the association between baseline self-efficacy and long-term risk of all-cause mortality over 25 years.

METHODS

The Americans' Changing Lives (ACL) study, 1986-2011, is a nationally representative longitudinal cohort of US adults. The study followed 3361 black (n = 1156) and white (n = 2205) adults for up to 25 years. General self-efficacy as well as demographics, socioeconomics, stressful life events, health behaviors, obesity, depressive symptoms, and self-rated health were measured at baseline in 1986. The outcome was time to all-cause mortality since 1986. Race was the focal moderator. Logistic regression and proportional hazards models were used for data analysis.

RESULTS

Although blacks had lower general self-efficacy, this association was fully explained by socioeconomic factors (education and income). Our logistic regression suggested interactions between race and education, self-rated health, and stress on general self-efficacy at baseline. Baseline general self-efficacy was associated with risk of mortality in the pooled sample. Race interacted with baseline general self-efficacy on mortality risk, suggesting stronger association for whites than blacks.

CONCLUSION

Black-white differences exist in psychosocial and health factors associated with self-efficacy in the USA. Low general self-efficacy does not increase mortality risk for blacks. Future research should test whether socioeconomic status, race-related attitudes, world views, attributions, and locus of control can potentially explain why low self-efficacy is not associated with higher risk of mortality among American blacks.

ORMDL3 expression levels have no influence on the activity of serine palmitoyltransferase

ORMDL proteins are believed to be negative regulators of serine palmitoyltransferase (SPT), which catalyzes the first and rate limiting step in sphingolipid (SL) de novo synthesis. Several single-nucleotide polymorphisms (SNPs) that are close to the ORMDL3 locus have been reported to increase ORMDL3 expression and to be associated with an elevated risk for early childhood asthma; however, the direct effect of ORMDL3 expression on SPT activity and its link to asthma remains elusive. In this study, we investigated whether ORMDL3 expression is associated with changes in SPT activity and total SL levels. Ormdl3-knockout (Ormdl3^-/-) and transgenic (Ormdl3^Tg/wt) mice were generated to study the effect of ORMDL3 on total SL levels in plasma and tissues. Cellular SPT activity was measured in mouse embryonic fibroblasts from Ormdl3^-/- mice, as well as in HEK293 cells in which ORMDL3 was overexpressed and silenced. Furthermore, we analyzed the association of the reported ORMDL3 asthma SNPs with plasma sphingoid bases in a population-based cohort of 971 individuals. Total C₁₈-long chain bases were not significantly altered in the plasma and tissues of Ormdl3^-/- mice, whereas C₁₈-sphinganine showed a small and significant increase in plasma, lung, and liver tissues. Mouse embryonic fibroblast cells from Ormdl3^-/- mice did not show an altered SPT activity compared with Ormdl3^+/- and Ormdl3^+/+ mice. Overexpression or knockdown of ORMDL3 in HEK293 cells did not alter SPT activity; however, parallel knockdown of all 3 ORMDL isoforms increased enzyme activity significantly. A significant association of the annotated ORMDL3 asthma SNPs with plasma long-chain sphingoid base levels could not be confirmed. ORMDL3 expression levels seem not to be directly associated with changes in SPT activity. ORMDL3 might influence de novo sphingolipid metabolism downstream of SPT.-Zhakupova, A., Debeuf, N., Krols, M., Toussaint, W., Vanhoutte, L., Alecu, I., Kutalik, Z., Vollenweider, P., Ernst, D., von Eckardstein, A., Lambrecht, B. N., Janssens, S., Hornemann, T. ORMDL3 expression levels have no influence on the activity of serine palmitoyltransferase.

Asthma as a disruption in iron homeostasis

Over several decades, asthma has evolved from being recognized as a single disease to include a diverse group of phenotypes with dissimilar natural histories, pathophysiologies, responses to treatment, and distinctive molecular pathways. With the application of Occam's razor to asthma, it is proposed that there is one cause underlying the numerous phenotypes of this disease and that the responsible molecular pathway is a deficiency of iron in the lung tissues. This deficiency can be either absolute (e.g. asthma in the neonate and during both pregnancy and menstruation) or functional (e.g. asthma associated with infections, smoking, and obesity). Comparable associations between asthma co-morbidity (e.g. eczema, urticaria, restless leg syndrome, and pulmonary hypertension) with iron deficiency support such a shared mechanistic pathway. Therapies directed at asthma demonstrate a capacity to impact iron homeostasis, further strengthening the relationship. Finally, pathophysiologic events producing asthma, including inflammation, increases in Th2 cells, and muscle contraction, can correlate with iron availability. Recognition of a potential association between asthma and an absolute and/or functional iron deficiency suggests specific therapeutic interventions including inhaled iron.

Environmental exposures and family history of asthma

BACKGROUND

Asthma pathogenesis is a complex interaction of genetic, ethnic, environmental and social/life style risk factors.

AIM

The goal of this study was to identify associations, if any, in children with asthma, between environmental risk factors (exposure to second-hand tobacco smoke (STS), pet ownership, race and a family history of asthma.

METHODS

After IRB approval, from June 2011 to December 2014, 823 children with asthma were enrolled in this prospective cross sectional study. At the initial visit, families completed a questionnaire with information on family history of asthma, having a pet at home and exposure to STS by parents at home. Chi square analyses were calculated, with alpha level of significance ≤0.05.

RESULTS

History of asthma in parents, siblings or grandparents was reported by 575 (69.8%) patients including father (n = 154, 17.8%) and mother (n = 235, 26.5%). Children with family history of asthma (n = 575) were significantly more likely to have a pet at home and exposure to STS (n = 347, 60.3% and n = 198, 34.4%, respectively) compared to families without a history of asthma (n = 124, 50%, p = 0.006 and n = 44, 17.7%, p < 0.001, respectively). Similarly, asthmatic children with exposure to STS (n = 241) were significantly more likely to have a pet at home and a family history of asthma (n = 153, 63.5% and n = 197, 81.7%, respectively) compared to children with no STS exposure (n = 315, 55.5%, p = 0.034 and n = 371, 65.3%, p < 0.001 respectively).

CONCLUSIONS

Significantly more asthmatic children with immediate relatives with a history of asthma have a pet at home and experience STS exposure compared to children without relatives with a history of asthma, suggesting association between life style choices/environmental exposures and family history of asthma.

Public and Population Health Genomics

Public health seeks to improve health at a population level through interventions that increase the net health benefit to the population as a whole. Advances in genomics knowledge and technologies can add to this endeavor, but also pose a challenge when faced with often conflicting public health (population) and genomic medicine (individual) perspectives. Combining the fields of genomic, population, and social sciences, population genomics or public health genomics looks at the promotion of health and prevention of disease using genomic knowledge through the lens of populations rather than individuals. In this chapter we will survey the three major disciplines contributing to population genomics (genomics, population, and social sciences) and explore two cross-cutting issues: global health and population versus individual health, using specific examples from diseases such as asthma, colon cancer, and cystic fibrosis.

Relationships between Psychosocial Resilience and Physical Health Status of Western Australian Urban Aboriginal Youth

BACKGROUND

Psychosocial processes are implicated as mediators of racial/ethnic health disparities via dysregulation of physiological responses to stress. Our aim was to investigate the extent to which factors previously documented as buffering the impact of high-risk family environments on Aboriginal youths' psychosocial functioning were similarly beneficial for their physical health status.

METHOD AND RESULTS

We examined the relationship between psychosocial resilience and physical health of urban Aboriginal youth (12-17 years, n = 677) drawn from a representative survey of Western Australian Aboriginal children and their families. A composite variable of psychosocial resilient status, derived by cross-classifying youth by high/low family risk exposure and normal/abnormal psychosocial functioning, resulted in four groups- Resilient, Less Resilient, Expected Good and Vulnerable. Separate logistic regression modeling for high and low risk exposed youth revealed that Resilient youth were significantly more likely to have lower self-reported asthma symptoms (OR 3.48, p<.001) and carer reported lifetime health problems (OR 1.76, p<.04) than Less Resilient youth.

CONCLUSION

The findings are consistent with biopsychosocial models and provide a more nuanced understanding of the patterns of risks, resources and adaptation that impact on the physical health of Aboriginal youth. The results support the posited biological pathways between chronic stress and physical health, and identify the protective role of social connections impacting not only psychosocial function but also physical health. Using a resilience framework may identify potent protective factors otherwise undetected in aggregated analyses, offering important insights to augment general public health prevention strategies.

Distal, intermediate, and proximal mediators of racial disparities in renal disease mortality in the United States

Background: Kidney failure and associated mortality is one of the major components of racial disparities in the United States.

Objectives: The current study aimed to investigate the role of distal (socioeconomic status, SES), intermediate (chronic medical diseases), and proximal (health behaviors) factors that may explain Black-White disparities in mortality due to renal diseases.

Patients and Methods: This is a nationally representative prospective cohort with 25 years of follow up. Data came from the Americans’ Changing Lives (ACL) study, 1986 to 2011. The study included 3361 Black (n = 1156) or White (n = 2205) adults who were followed for up to 25 years. Race was the main predictor and death due to renal disease was the outcome. SES, chronic medical disease (diabetes, hypertension, obesity), and health behaviors (smoking, drinking, and exercise) at baseline were potential mediators. We used Cox proportional hazards models for data analysis.

Results: In age and gender adjusted models, Blacks had higher risk of death due to renal disease over the follow up period. Separate models suggested that SES, health behaviors and chronic medical disease fully explained the effect of race on renal disease mortality.

Conclusions: Black-White disparities in rate of death due to renal diseases in the United States are not genuine but secondary to racial differences in income, health behaviors, hypertension, and diabetes. As distal, intermediate, and proximal factors contribute to racial disparities in renal disease mortality, elimination of such disparities requires a wide range of policies and programs that target income, medical conditions, and health behaviors.

A reconsideration of the role of self-identified races in epidemiology and biomedical research

A considerable number of studies in epidemiology and biomedicine investigate the etiology of complex diseases by considering (self-identified) race as a relevant variable and focusing on the differences in risk among racial groups in the United States; they extensively draw on a genetic hypothesis--viz. the hypothesis that differences in the risk of complex diseases among racial groups are largely due to genetic differences covarying with genetic ancestry--that appears highly problematic in the light of both current biological evidence and the theory of human genome evolution. Is this reason for dismissing self-identified races? No. An alternative promising use of self-identified races exists, and ironically is suggested by those studies that investigate the etiology of complex diseases without focusing on racial differences. These studies provide a large amount of empirical evidence supporting the primacy of the contribution of non-genetic as opposed to genetic factors to the risk of complex diseases. We show that differences in race--or, better, in racial self-identification--may be critically used as proxies for differences in risk-related exposomes and epigenomes in the context of the United States. Self-identified race is what we need to capture the complexity of the effects of present and past racism on people's health and investigate risk-related external and internal exposures, gene-environment interactions, and epigenetic events. In fact patterns of racial self-identifications on one side, and patterns of risk-related exposomes and epigenomes on the other side, constantly coevolve and tend to match each other. However, there is no guarantee that using self-identified races in epidemiology and biomedical research will be beneficial all things considered: special attention must be paid at balancing positive and negative consequences.

Mine dumps, wheeze, asthma, and rhinoconjunctivitis among adolescents in South Africa: any association?

The study investigated the association between community proximity to mine dumps, and current wheeze, rhinoconjunctivitis, and asthma among adolescents. This study was conducted during May-November 2012 around five mine dumps in South Africa. Communities in close proximity to mine dumps had an increased likelihood of current wheeze OR 1.38 (95 % CI: 1.10-1.71), rhinoconjunctivitis OR 1.54 (95 % CI: 1.29-1.82), and a protective association with asthma OR 0.29 (95 % CI: 0.23-0.35). Factors associated with health outcomes included other indoor and outdoor pollution sources. Wheeze and rhinoconjunctivitis appear to be a public health problem in these communities. The findings of this study serve as a base for further detailed epidemiological studies for communities in close proximity to the mine dumps e.g. a planned birth cohort study.

Role of financial and social hardships in asthma racial disparities

BACKGROUND AND OBJECTIVES

Health care reform offers a new opportunity to address child health disparities. This study sought to characterize racial differences in pediatric asthma readmissions with a focus on the potential explanatory role of hardships that might be addressed in future patient care models.

METHODS

We enrolled 774 children, aged 1 to 16 years, admitted for asthma or bronchodilator-responsive wheezing in a population-based prospective observational cohort. The outcome was time to readmission. Child race, socioeconomic status (measured by lower income and caregiver educational attainment), and hardship (caregivers looking for work, having no one to borrow money from, not owning a car or home, and being single/never married) were recorded. Analyses used Cox proportional hazards.

RESULTS

The cohort was 57% African American, 33% white, and 10% multiracial/other; 19% were readmitted within 12 months. After adjustment for asthma severity classification, African Americans were twice as likely to be readmitted as whites (hazard ratio: 1.98; 95% confidence interval: 1.42 to 2.77). Compared with whites, African American caregivers were significantly more likely to report lower income and educational attainment, difficulty finding work, having no one to borrow money from, not owning a car or home, and being single/never married (all P ≤ .01). Hardships explained 41% of the observed racial disparity in readmission; jointly, socioeconomic status and hardship explained 49%.

CONCLUSIONS

African American children were twice as likely to be readmitted as white children; hardships explained >40% of this disparity. Additional factors (eg, pollution, tobacco exposure, housing quality) may explain residual disparities. Targeted interventions could help achieve greater child health equity.

Socioeconomic status and childhood asthma in urban minority youths. The GALA II and SAGE II studies

RATIONALE

The burden of asthma is highest among socioeconomically disadvantaged populations; however, its impact is differentially distributed among racial and ethnic groups.

OBJECTIVES

To assess the collective effect of maternal educational attainment, annual household income, and insurance type on childhood asthma among minority, urban youth.

METHODS

We included Mexican American (n = 485), other Latino (n = 217), and African American (n = 1,141) children (aged 8-21 yr) with and without asthma from the San Francisco Bay Area. An index was derived from maternal educational attainment, annual household income, and insurance type to assess the collective effect of socioeconomic status on predicting asthma. Logistic regression stratified by racial and ethnic group was used to estimate adjusted odds ratios (aOR) and their 95% confidence intervals (CI). We further examined whether acculturation explained the socioeconomic-asthma association in our Latino population.

MEASUREMENTS AND MAIN RESULTS

In the adjusted analyses, African American children had 23% greater odds of asthma with each decrease in the socioeconomic index (aOR, 1.23; 95% CI, 1.09-1.38). Conversely, Mexican American children have 17% reduced odds of asthma with each decrease in the socioeconomic index (aOR, 0.83; 95% CI, 0.72-0.96) and this relationship was not fully explained by acculturation. This association was not observed in the other Latino group.

CONCLUSIONS

Socioeconomic status plays an important role in predicting asthma, but has different effects depending on race and ethnicity. Further steps are necessary to better understand the risk factors through which socioeconomic status could operate in these populations to prevent asthma.

The prevalence of asthma in Canadian children of South Asian descent

BACKGROUND

Asthma is the most common disease in childhood. The prevalence of asthma is known to vary greatly between and within countries and among different ethnic groups. In this study, we aimed to determine the prevalence of asthma and wheezing symptoms in South Asian children living in Canada.

METHODS

In a cross sectional study, data from the Phase III International Study on Asthma and Allergies in Childhood (ISAAC) were analyzed. A surname algorithm to determine South Asian ethnic descent was used. Prevalence was calculated and compared to non-South Asian children from the same survey and to the reported prevalence from the Indian subcontinent ISAAC III survey for children ages 6-9 and 13-16.

RESULTS

The prevalence of asthma and wheezing did not differ between children of South Asian descent and non-South Asians living Canada. When compared to the children living in India, the prevalence of asthma, wheeze, and exercise induced wheeze was significantly higher in the South Asian children living in Canada. Higher body mass index of the child, parental smoking, and pet ownership were strongly associated with asthma and wheeze.

CONCLUSIONS

In contrast to other studies these data suggest that South Asian children living in Canada have a similar asthma prevalence to non-South Asian children; both of whom had higher asthma prevalence compared with children residing in South Asia. This suggests that environmental and social factors play a role in asthma prevalence. Risk factors for asthma in children of South Asian descent living in Canada are similar to those of the overall population.

Association between birthplace and current asthma: the role of environment and acculturation

OBJECTIVES

We evaluated associations between current asthma and birthplace among major racial/ethnic groups in the United States.

METHODS

We used multivariate logistic regression methods to analyze data on 102,524 children and adolescents and 255,156 adults in the National Health Interview Survey (2001-2009).

RESULTS

We found significantly higher prevalence (P < .05) of current asthma among children and adolescents (9.3% vs 5.1%) and adults (7.6% vs 4.7%) born in the 50 states and Washington, DC (US-born), than among those born elsewhere. These differences were among all age groups of non-Hispanic Whites, non-Hispanic Blacks, and Hispanics (excluding Puerto Ricans) and among Chinese adults. Non-US-born adults with 10 or more years of residency in the United States had higher odds of current asthma (odds ratio = 1.55; 95% confidence interval = 1.25, 1.93) than did those who arrived more recently. Findings suggested a similar trend among non-US-born children.

CONCLUSIONS

Current asthma status was positively associated with being born in the United States and with duration of residency in the United States. Among other contributing factors, changes in environment and acculturation may explain some of the differences in asthma prevalence.

Asthma disparities and within-group differences in a national, probability sample of same-sex partnered adults

OBJECTIVES

We examined the prevalence and correlates of self-reported lifetime diagnosis of asthma and current asthma among same-sex and opposite-sex partnered adults.

METHODS

Data were from the 2004 Behavioral Risk Factor Surveillance System, in which same-sex partnership was a response option to a family planning item in the core questionnaire. Self-reported lifetime diagnosis of asthma and current asthma were examined in logistic regression models adjusted for demographic characteristics and asthma-related confounding factors and stratified by both gender and same-sex partnership status.

RESULTS

Significantly higher proportions of same-sex partnered male and female respondents reported lifetime and current asthma compared with their opposite-sex partnered peers. In adjusted analyses, same-sex partnership status remained significantly associated with asthma outcomes among men and women, with odds ratios ranging from 1.57 to 2.34.

CONCLUSIONS

Results corroborated past studies that indicated asthma disproportionately affects sexual minority populations. The addition of sexual minority status questions to federal survey projects is key to further exploring health disparities in this population. Future studies are needed to investigate the etiology of this disparity.

The outdoor air pollution and brain health workshop

Accumulating evidence suggests that outdoor air pollution may have a significant impact on central nervous system (CNS) health and disease. To address this issue, the National Institute of Environmental Health Sciences/National Institute of Health convened a panel of research scientists that was assigned the task of identifying research gaps and priority goals essential for advancing this growing field and addressing an emerging human health concern. Here, we review recent findings that have established the effects of inhaled air pollutants in the brain, explore the potential mechanisms driving these phenomena, and discuss the recommended research priorities/approaches that were identified by the panel.

Asthma Research for All of the United States

Asthma disproportionally affects different ethnic/racial groups, with Puerto Ricans and African Americans suffering the highest asthma prevalence and morbidity, Mexicans the lowest, and non-Hispanic whites in between. Genome-wide association studies of asthma have found both shared and race/ethnic-specific genetic risks factors for asthma. However, the majority of genetic asthma research is performed in populations of European descent, which limits the benefits of genetic research to European populations. It is important to biomedical and clinical research to include more diverse and underrepresented populations. The rich genetic diversity of all populations can be leveraged to scientific advantage. For example, admixture mapping provides a more powerful approach than traditional genome-wide allelic association studies in discovering genetic associations for complex diseases. By being more inclusive we can achieve a better understanding of the genetics of asthma, address health disparities, and ensure that scientific advances will benefit populations worldwide.

Exposures to fine particulate air pollution and respiratory outcomes in adults using two national datasets: a cross-sectional study

BACKGROUND

Relationships between chronic exposures to air pollution and respiratory health outcomes have yet to be clearly articulated for adults. Recent data from nationally representative surveys suggest increasing disparity by race/ethnicity regarding asthma-related morbidity and mortality. The objectives of this study are to evaluate the relationship between annual average ambient fine particulate matter (PM2.5) concentrations and respiratory outcomes for adults using modeled air pollution and health outcome data and to examine PM2.5 sensitivity across race/ethnicity.

METHODS

Respondents from the 2002-2005 National Health Interview Survey (NHIS) were linked to annual kriged PM2.5 data from the USEPA AirData system. Logistic regression was employed to investigate increases in ambient PM2.5 concentrations and self-reported prevalence of respiratory outcomes including asthma, sinusitis and chronic bronchitis. Models included health, behavioral, demographic and resource-related covariates. Stratified analyses were conducted by race/ethnicity.

RESULTS

Of nearly 110,000 adult respondents, approximately 8,000 and 4,000 reported current asthma and recent attacks, respectively. Overall, odds ratios (OR) for current asthma (0.97 (95% Confidence Interval: 0.87-1.07)) and recent attacks (0.90 (0.78-1.03)) did not suggest an association with a 10 μg/m3 increase in PM2.5. Stratified analyses revealed significant associations for non-Hispanic blacks [OR = 1.73 (1.17-2.56) for current asthma and OR = 1.76 (1.07-2.91) for recent attacks] but not for Hispanics and non-Hispanic whites. Significant associations were observed overall (1.18 (1.08-1.30)) and in non-Hispanic whites (1.31 (1.18-1.46)) for sinusitis, but not for chronic bronchitis.

CONCLUSIONS

Non-Hispanic blacks may be at increased sensitivity of asthma outcomes from PM2.5 exposure. Increased chronic PM2.5 exposures in adults may contribute to population sinusitis burdens.

Ethnicity and risk of hospitalization for asthma and chronic obstructive pulmonary disease

PURPOSE

To identify ethnic differences for risk of hospitalization for asthma and chronic obstructive pulmonary disease (COPD).

METHODS

We undertook a cohort study with 126,019 participants: 55% whites, 27% blacks, 11% Asians, and 4% Hispanics. To estimate asthma and COPD risk, we used Cox proportional hazards models adjusted for age, sex, body mass index, education, smoking, and alcohol intake. End points were hospitalizations for asthma or COPD.

RESULTS

Compared with whites, relative risks (RR) with 95% confidence intervals (95% CI) for asthma among other groups were: blacks, 1.7 (1.4-2.0); Hispanics, 0.9 (0.6-1.4); and Asians, 1.6 (1.2-2.1). Among Asians, increased risk was concentrated in Filipino men and women and South Asian men. For COPD, whites were at highest risk; RR of blacks was 0.9 (0.7-1.0); Hispanics, 0.6 (0.3- 0.9); and Asians, 0.4 (0.3-0.6). COPD risk among Asians was lowest in Chinese with RR of 0.3 (0.1-0.5).

CONCLUSIONS

Ethnic disparities in risk of asthma and COPD as well as between both diseases exist, especially for Asian Americans, who have high asthma risk and low COPD risk. While residual confounding for smoking or other environmental factors could be partially responsible, genetic factors in Asians may be involved in decreased COPD risk.

Conceptual framework of the Controlling Asthma in American Cities Project

The Controlling Asthma in American Cities Project (CAACP) was designed to improve the control of asthma in inner-city populations of children with a disparate burden of symptoms and adverse outcomes. As with many chronic diseases, asthma is the manifestation of multiple biologic, environmental, and social determinants. In addition to appropriate medical management, individuals with asthma must have logistical, financial, and cultural access to environments that allow avoidance of asthma triggers and encourage good asthma management practices. In recognition of this complexity, the CAACP required the seven project sites to coordinate and synchronize multiple interventions (education, healthcare access, medical management, trigger reduction) at multiple levels (individual, home, school, community, and policy) through the collaboration of relevant groups, institutions, and individuals. This paper describes the "program theory" of the CAACP project-the assumptions about how the project worked, how the components were linked, and what outcomes were anticipated. It relates the subsequent papers in the supplement to the program theory and describes how the papers can inform and guide other community-based interventions, and advance the translation of scientific knowledge to effective interventions in communities of need.

Unraveling the genetic basis of asthma and allergic diseases

Asthma and allergic diseases are believed to be complex genetic diseases which may result from the interaction of multiple genetic factors and environmental stimuli. In past decades, great efforts have been exerted in unraveling their genetic basis. The strategies in discovering genes and genetic variants, confirming their importance in pathogenesis of asthma and allergic diseases, as well as their strengths and limitations are summarized comprehensively and concisely. The current consensus about the genetic basis of asthma and allergic diseases is briefly described as well.

Recent advances of genetic ancestry testing in biomedical research and direct to consumer testing

In the post-Human Genome Project era, the debate on the concept of race/ethnicity and its implications for biomedical research are dependent on two critical issues: whether and how to classify individuals and whether biological factors play a role in health disparities. The advent of reliable estimates of genetic (or biogeographic) ancestry has provided this debate with a quantitative and more objective tool. The estimation of genetic ancestry allows investigators to control for population stratification in association studies and helps to detect biological causation behind population-specific differences in disease and drug response. New techniques such as admixture mapping can specifically detect population-specific risk alleles for a disease in admixed populations. However, researchers have to be mindful of the correlation between genetic ancestry and socioeconomic and environmental factors that could underlie these differences. More importantly, researchers must avoid the stigmatization of individuals based on perceived or real genetic risks. The latter point will become increasingly sensitive as several 'for profit companies' are offering ancestry and genetic testing directly to consumers and the consequences of the spread of the services of these companies are still unforeseeable.

The role of LTA4H and ALOX5AP genes in the risk for asthma in Latinos

BACKGROUND

Leukotrienes play an important role in allergic and inflammatory diseases, but reports on the involvement of arachidonate 5-lipoxygenase-activating protein (ALOX5AP) and leukotriene A(4) hydrolase (LTA4H) in asthma have been inconclusive.

OBJECTIVE

To determine whether polymorphisms in ALOX5AP and LTA4H genes are risk factors for asthma in two different Latino groups: Mexicans and Puerto Ricans.

METHODS

The LTA4H gene was sequenced in individuals from both groups to identify novel polymorphisms. Single-nucleotide polymorphisms (SNPs) in the ALOX5AP and LTA4H genes were analysed for associations with asthma and asthma-related phenotypes in 687 parent-child trios of Mexican and Puerto Rican origin.

RESULTS

In LTA4H, five previously unknown polymorphisms were identified. Two SNPs within LTA4H (rs17525488 and rs2540493) were protective for asthma in Latinos (P=0.007 and 0.05, respectively). Among the Mexican patients, LTA4H polymorphisms were associated with baseline lung function and IgE levels. For ALOX5AP, the minor allele at SNP rs10507391 was associated with protection from asthma (odds ratio=0.78, P=0.02) and baseline lung function (P=0.018) in Puerto Ricans. A gene-gene interaction was identified between LTA4H (rs17525488) and ALOX5AP (rs10507391), (P=0.003, in the combined sample).

CONCLUSION

Our results support the role of LTA4H and ALOX5AP variants as risk factors for asthma in Latino populations.

Genetic variants of GSNOR and ADRB2 influence response to albuterol in African-American children with severe asthma

African Americans are disproportionately affected by asthma. Social and economic factors play a role in this disparity, but there is evidence that genetic factors may also influence the development of asthma and response to therapy in African American children. Our hypothesis is that variations in asthma related genes contribute to the observed asthma disparities by influencing the response to asthma-specific therapy. In order to test this hypothesis, we characterized the clinical response to asthma-specific therapy in 107 African American children who presented to the emergency room in status asthmaticus, with a primary outcome indicator of length of time on continuous albuterol. Single locus analysis indicated that genotype variation in glutathione-dependent S-nitrosoglutathione reductase (GSNOR) is associated with a decreased response to asthma treatment in African American children. A post hoc multi-locus analysis revealed that a combination of four single nucleotide polymorphisms (SNPs) within GSNOR, adrenergic receptor beta 2, and carbamoyl phosphate synthetase-1 give a 70% predictive value for lack of response to therapy. This predictive model needs replication in other cohorts of patients with asthma, but suggests gene-gene interactions may have greater significance than that identified with single variants. Our findings also suggest that genetic variants may contribute to the observed population disparities in asthma.

Cytokine SNPs: Comparison of allele frequencies by race and implications for future studies

The role of inflammation is being considered in chronic diseases. Previous studies have examined SNPs in a few key inflammatory genes and have included small numbers of African American participants. Variation in the frequencies of inflammatory pathway SNPs may help to explain racial disparities in disease risk. Through a population-based study of 103 African American and 380 Caucasian unrelated, healthy women, we examined the relationships between race and allele frequencies of 70 cytokine and cytokine receptor SNPs. The associations between genotypic and haplotype frequencies and race were also analyzed. Allelic frequencies for 52 out of the 70 SNPs meeting criteria for analysis differed significantly by race. Of the 32 pro-inflammatory and 20 anti-inflammatory SNPs for which the allele frequencies varied significantly by race, variant allele frequency differences between Caucasians and African Americans ranged between 6-37% and 7-53% for pro-inflammatory SNPs and anti-inflammatory SNPs, respectively. Our findings suggest that while allele frequencies do vary by race, racial groups are not simplistically represented by a pro-inflammatory or anti-inflammatory genetic profile. Given the racial variability in allele frequencies in inflammatory gene SNPs, studies examining the association between these SNPs and disease should at least incorporate self-reported race in their analyses.

Ancestry in translational genomic medicine: handle with care

Disparities in health outcomes of members of different ancestral or ethnic groups can be observed in both developed and developing countries and continue to be a global concern. Genomic medicine can help toward closing this gap by expanding the knowledge on novel alleles related to disease risk and drug response, their frequencies, and their relation with disease and drug-response phenotypes, in as many countries and ethnic groups as possible. Without such knowledge, genomic medicine cannot deliver upon its promise of contributing to health for all. However, the use of ancestry or ethnicity-related genetic information as a selection criterion for assigning varying levels of access to health care is condemnable. Translational genomic medicine will allow for individualized clinical decision making - doing away with the use of race, ethnicity or ancestry as a proxy.

An african-specific functional polymorphism in KCNMB1 shows sex-specific association with asthma severity

A highly heritable and reproducible measure of asthma severity is baseline pulmonary function. Pulmonary function is largely determined by airway smooth muscle (ASM) tone and contractility. The large conductance, voltage and calcium-activated potassium (BK) channel negatively regulates smooth muscle tone and contraction in ASM. The modulatory subunit of BK channels, the beta1-subunit, is critical for proper activation of BK channels in smooth muscle and has shown sex hormone specific regulation. We hypothesized that KCNMB1 genetic variants in African Americans may underlie differences in bronchial smooth muscle tone and thus pulmonary function, possibly in a sex-specific manner. Through resequencing of the KCNMB1 gene we identified several common variants including a novel African-specific coding polymorphism (C818T, R140W). The C818T SNP and four other KCNMB1 variants were genotyped in two independent groups of African American asthmatics (n = 509) and tested for association with the pulmonary function measure--forced expiratory volume (FEV(1)) % of predicted value. The 818T allele is associated with a clinically significant decline (-13%) in FEV(1) in both cohorts of asthmatics among males but not females (P(combined) = 0.0003). Patch clamp electrophysiology studies of the BK channel expressed with the 140Trp variant of the beta1-subunit demonstrated significantly reduced channel openings, predicted by the loss of pulmonary function observed. African American male asthmatics carrying the 818T allele (10% of population) are potentially at risk for greater airway obstruction and increased asthma morbidity. Female asthmatics may be insulated from the deleterious effects of the 818T allele by estrogen-mediated upregulation in BK channel activity.