Elevated asthma morbidity in Puerto Rican children: a review of possible risk and prognostic factors

Latino children represent a significant proportion of all US children, and asthma is the most common chronic illness affecting them. Previous research has revealed surprising differences in health among Latino children with asthma of varying countries of family origin. For instance, Puerto Rican children have a higher prevalence of asthma than Mexican American or Cuban American children. In addition, there are important differences in family structure and socioeconomic status among these Latino populations: Cuban Americans have higher levels of education and family income than Mexican-Americans and Puerto Ricans; mainland Puerto Rican children have the highest proportion of households led by a single mother. Our review of past research documents differences in asthma outcomes among Latino children and identifies the possible genetic, environmental, and health care factors associated with these differences. Based on this review, we propose research studies designed to differentiate between mutable and immutable risk and prognostic factors. We also propose that the sociocultural milieus of Latino subgroups of different ethnic and geographic origin are associated with varying patterns of risk factors that in turn lead to different morbidity patterns. Our analysis provides a blue-print for future research, policy development, and the evaluation of multifactorial interventions involving the collaboration of multiple social sectors, such as health care, public health, education, and public and private agencies.     

Population structure of Hispanics in the United States: the multi-ethnic study of atherosclerosis

Using ∼60,000 SNPs selected for minimal linkage disequilibrium, we perform population structure analysis of 1,374 unrelated Hispanic individuals from the Multi-Ethnic Study of Atherosclerosis (MESA), with self-identification corresponding to Central America (n = 93), Cuba (n = 50), the Dominican Republic (n = 203), Mexico (n = 708), Puerto Rico (n = 192), and South America (n = 111). By projection of principal components (PCs) of ancestry to samples from the HapMap phase III and the Human Genome Diversity Panel (HGDP), we show the first two PCs quantify the Caucasian, African, and Native American origins, while the third and fourth PCs bring out an axis that aligns with known South-to-North geographic location of HGDP Native American samples and further separates MESA Mexican versus Central/South American samples along the same axis. Using k-means clustering computed from the first four PCs, we define four subgroups of the MESA Hispanic cohort that show close agreement with self-identification, labeling the clusters as primarily Dominican/Cuban, Mexican, Central/South American, and Puerto Rican. To demonstrate our recommendations for genetic analysis in the MESA Hispanic cohort, we present pooled and stratified association analysis of triglycerides for selected SNPs in the LPL and TRIB1 gene regions, previously reported in GWAS of triglycerides in Caucasians but as yet unconfirmed in Hispanic populations. We report statistically significant evidence for genetic association in both genes, and we further demonstrate the importance of considering population substructure and genetic heterogeneity in genetic association studies performed in the United States Hispanic population.     

Self-Reported Cancer Prevalence among Hispanics in the US: Results from the Hispanic Community Health Study/Study of Latinos

Cancer has surpassed heart disease as the leading cause of death among Hispanics in the U.S., yet data on cancer prevalence and risk factors in Hispanics in regard to ancestry remain scarce. This study sought to describe (a) the prevalence of cancer among Hispanics from four major U.S. metropolitan areas, (b) cancer prevalence across Hispanic ancestry, and (c) identify correlates of self-reported cancer prevalence. Participants were 16,415 individuals from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), who self-identified as Cuban, Dominican, Mexican, Puerto Rican, Central or South American. All data were collected at a single time point during the HCHS/SOL baseline clinic visit. The overall self-reported prevalence rate of cancer for the population was 4%. The rates varied by Hispanic ancestry group, with individuals of Cuban and Puerto Rican ancestry reporting the highest cancer prevalence. For the entire population, older age (OR = 1.47, p < .001, 95% CI, 1.26–1.71) and having health insurance (OR = 1.93, p < .001, 95% CI, 1.42–2.62) were all significantly associated with greater prevalence, whereas male sex was associated with lower prevalence (OR = 0.56, p < .01, 95% CI, .40-.79). Associations between study covariates and cancer prevalence also varied by Hispanic ancestry. Findings underscore the importance of sociodemographic factors and health insurance in relation to cancer prevalence for Hispanics and highlight variations in cancer prevalence across Hispanic ancestry groups. Characterizing differences in cancer prevalence rates and their correlates is critical to the development and implementation of effective prevention strategies across distinct Hispanic ancestry groups.     

From Puerto Rican to pan-ethnic in New York city

Abstract

The increasing diversity of the US population has stimulated interest in racial identification, which is complex for phenotypically heterogeneous groups such as Puerto Ricans. We overcome several limitations of the empirical literature on racial identification among Puerto Ricans with a study that is grounded in the experience of Puerto Rican women in New York City. Our analysis focuses on two questions: How do Puerto Rican women in New York identify themselves racially? What are the sources of racial identification? The results indicate that most Puerto Rican women in New York conflate race and ethnicity by designating their race as either ‘Puerto Rican’ or ‘Hispanic’. Moreover, the decision to ‘become’ pan-ethnic has complex roots. In particular, the effect of skin tone on pan-ethnic identification is conditioned by socioeconomic and neighbourhood characteristics.     

Admixture in Hispanics: distribution of ancestral population contributions in the Continental United States

The effect of gene flow on Hispanic populations from different geographic regions of the United States was analyzed using six autosomal DNA markers (LDLR, GYPA, HBGG, D7S8, GC, and HLA-DQA). By region of sampling, the Hispanic populations showed different ancestry contributions, from a trihybrid structure with European, Native American, and African contributions (California, Nevada, Florida, New Jersey, and Virginia) to a dihybrid structure with European and American contributions (Southwest population) or European and African contributions (Pennsylvania and Southeast population). These findings allowed us to define two regional groups, the West and the East. In the former, Native American contributions ranged from 35.58% to 57.87%; in the East region the values ranged from 0% to 21.27%. An African influence was similar in both regions, ranging from 0% to 17.11%, with a tendency of increasing in the East region. These data reflect the different origins of the Hispanic populations that led to the present ones. In the West, Hispanics are mostly of Mexican origin, and in the East, they are predominantly of Cuban and Puerto Rican origin.     

Determinants of physical activity among a convenience sample of Puerto Rican women residing in the Northeastern United States

The research examining determinants of physical activity among Hispanics focuses on Mexican Americans, although Puerto Ricans are the second largest Hispanic subgroup in the United States. The purpose of this study was to explore factors influencing physical activity among Puerto Rican women in the urban northeastern United States. Two bilingual female investigators administered the Women and Physical Activity Survey by telephone to a convenience sample of Puerto Rican women (n = 28). Women were categorized as physically active if they performed moderate-intensity physical activity for at least 30 minutes a day at least 5 days a week or vigorous-intensity physical activity for at least 20 minutes a day at least 3 days a week. Women not meeting these criteria were classified as physically inactive. Chi-squared testing revealed whether the physically active and inactive women differed among physical activity determinants. Respondents had a mean age of 36 years and were predominately college-educated (64%) and physically active (68%). More physically active women (90%) had an annual income of more than $35,000 than did the inactive women (10%) (p < 0.05). More physically active women belonged to community groups (42% versus 0%), lived in communities where people exercise (95% versus 11%), and felt their community was good for their family (100% versus 67%) than did the inactive women, respectively (p < 0.05). The physically active women reported the presence of exercise facilities (p = 0.084) and well-maintained sidewalks (p = 0.087) to be more important for exercise accessibility than did the inactive women. Annual income, sense of community, and exercise accessibility were the most important physical activity determinants in this convenience sample of Puerto Rican women. Factors influencing the physical activity levels of Puerto Rican women should continue to be explored so that targeted, culturally appropriate strategies can be developed to promote physically activity in this population.     

Genetic Diversity and Association Studies in US Hispanic/Latino Populations: Applications in the Hispanic Community Health Study/Study of Latinos

US Hispanic/Latino individuals are diverse in genetic ancestry, culture, and environmental exposures. Here, we characterized and controlled for this diversity in genome-wide association studies (GWASs) for the Hispanic Community Health Study/Study of Latinos (HCHS/SOL). We simultaneously estimated population-structure principal components (PCs) robust to familial relatedness and pairwise kinship coefficients (KCs) robust to population structure, admixture, and Hardy-Weinberg departures. The PCs revealed substantial genetic differentiation within and among six self-identified background groups (Cuban, Dominican, Puerto Rican, Mexican, and Central and South American). To control for variation among groups, we developed a multi-dimensional clustering method to define a “genetic-analysis group” variable that retains many properties of self-identified background while achieving substantially greater genetic homogeneity within groups and including participants with non-specific self-identification. In GWASs of 22 biomedical traits, we used a linear mixed model (LMM) including pairwise empirical KCs to account for familial relatedness, PCs for ancestry, and genetic-analysis groups for additional group-associated effects. Including the genetic-analysis group as a covariate accounted for significant trait variation in 8 of 22 traits, even after we fit 20 PCs. Additionally, genetic-analysis groups had significant heterogeneity of residual variance for 20 of 22 traits, and modeling this heteroscedasticity within the LMM reduced genomic inflation for 19 traits. Furthermore, fitting an LMM that utilized a genetic-analysis group rather than a self-identified background group achieved higher power to detect previously reported associations. We expect that the methods applied here will be useful in other studies with multiple ethnic groups, admixture, and relatedness.     

Predictors of excessive and inadequate gestational weight gain in Hispanic women

Factors influencing gestational weight gain are incompletely understood, particularly among Hispanic women. We assessed medical, sociodemographic, behavioral, and psychosocial predictors of overall gestational weight gain, as well as gains below, within, or above the range recommended by the Institute of Medicine (IOM) within a prospective study of 770 Hispanic (predominantly Puerto Rican) prenatal care patients at a large tertiary care facility in Western Massachusetts. One third of women gained within the recommended range, 22% gained below, and 45% gained above the range. In multivariate analysis, women in the highest category of BMI (P(trend)<0.001) and parity (P(trend)<0.001) gained on average 9 lbs less than those in the lowest category. Increasing time in residence in the continental United States (P(trend)<0.01) as well as a number of prenatal care visits (P(trend)=0.03) were positively associated with weight gain. Overweight women (odds ratio (OR)=2.2, 95% confidence interval (CI) 1.3, 3.8) and those over age 30 years (OR=2.5, 95% CI 1.2, 5.0) were more likely to gain above the IOM range as compared to normal-weight women and those aged 20-24, respectively. Women with <10 years of residence in the United States were 50% less likely to gain above the IOM range as compared to third-generation women (95% CI 0.3, 0.9). Findings identify determinants of gestational weight gain which can form the basis of targeted interventions in this rapidly growing ethnic group.     

Similarity and difference among rainforest fruit-feeding butterfly communities in Central and South America

1. Documenting species abundance distributions in natural environments is critical to ecology and conservation biology. Tropical forest insect faunas vary in space and time, and these partitions can differ in their contribution to overall species diversity. 2. In the Neotropics, the Central American butterfly fauna is best known in terms of general natural history, but butterfly community diversity is best documented by studies on South American fruit-feeding butterflies. Here, we present the first long-term study of fruit-feeding nymphalid species diversity from Central America and provide a unique comparison between Central and South American butterfly communities. 3. This study used 60 months of sampling among multiple spatial and temporal partitions to assess species diversity in a Costa Rican rainforest butterfly community. Abundance distributions varied significantly at the species and higher taxonomic group levels, and canopy and understorey samples were found to be composed of distinct species assemblages. 4. Strong similarities in patterns of species diversity were found between this study and one from Ecuador; yet, there was an important difference in how species richness was distributed in vertical space. In contrast to the Ecuadorian site, Costa Rica had significantly higher canopy richness and lower understorey richness. 5. This study affirms that long-term sampling is vital to understanding tropical insect species abundance distributions and points to potential differences in vertical structure among Central and South American forest insect communities that need to be explored.     

Population Genetic Inference from Personal Genome Data: Impact of Ancestry and Admixture on Human Genomic Variation

Full sequencing of individual human genomes has greatly expanded our understanding of human genetic variation and population history. Here, we present a systematic analysis of 50 human genomes from 11 diverse global populations sequenced at high coverage. Our sample includes 12 individuals who have admixed ancestry and who have varying degrees of recent (within the last 500 years) African, Native American, and European ancestry. We found over 21 million single-nucleotide variants that contribute to a 1.75-fold range in nucleotide heterozygosity across diverse human genomes. This heterozygosity ranged from a high of one heterozygous site per kilobase in west African genomes to a low of 0.57 heterozygous sites per kilobase in segments inferred to have diploid Native American ancestry from the genomes of Mexican and Puerto Rican individuals. We show evidence of all three continental ancestries in the genomes of Mexican, Puerto Rican, and African American populations, and the genome-wide statistics are highly consistent across individuals from a population once ancestry proportions have been accounted for. Using a generalized linear model, we identified subtle variations across populations in the proportion of neutral versus deleterious variation and found that genome-wide statistics vary in admixed populations even once ancestry proportions have been factored in. We further infer that multiple periods of gene flow shaped the diversity of admixed populations in the Americas—70% of the European ancestry in today’s African Americans dates back to European gene flow happening only 7–8 generations ago.     

Ancestry-related assortative mating in Latino populations

Background

While spouse correlations have been documented for numerous traits, no prior studies have assessed assortative mating for genetic ancestry in admixed populations.

Results

Using 104 ancestry informative markers, we examined spouse correlations in genetic ancestry for Mexican spouse pairs recruited from Mexico City and the San Francisco Bay Area, and Puerto Rican spouse pairs recruited from Puerto Rico and New York City. In the Mexican pairs, we found strong spouse correlations for European and Native American ancestry, but no correlation in African ancestry. In the Puerto Rican pairs, we found significant spouse correlations for African ancestry and European ancestry but not Native American ancestry. Correlations were not attributable to variation in socioeconomic status or geographic heterogeneity. Past evidence of spouse correlation was also seen in the strong evidence of linkage disequilibrium between unlinked markers, which was accounted for in regression analysis by ancestral allele frequency difference at the pair of markers (European versus Native American for Mexicans, European versus African for Puerto Ricans). We also observed an excess of homozygosity at individual markers within the spouses, but this provided weaker evidence, as expected, of spouse correlation. Ancestry variance is predicted to decline in each generation, but less so under assortative mating. We used the current observed variances of ancestry to infer even stronger patterns of spouse ancestry correlation in previous generations.

Conclusions

Assortative mating related to genetic ancestry persists in Latino populations to the current day, and has impacted on the genomic structure in these populations.     

Population stratification confounds genetic association studies among Latinos

In the United States, asthma prevalence and mortality are the highest among Puerto Ricans and the lowest among Mexicans. Case-control association studies are a powerful strategy for identifying genes of modest effect in complex diseases. However, studies of complex disorders in admixed populations such as Latinos may be confounded by population stratification. We used ancestry informative markers (AIMs) to identify and correct for population stratification among Mexican and Puerto Rican subjects participating in case-control studies of asthma. Three hundred and sixty-two subjects with asthma (Mexican: 181, Puerto Rican: 181) and 359 ethnically matched controls (Mexican: 181, Puerto Rican: 178) were genotyped for 44 AIMs. We observed a greater than expected degree of association between pairs of AIMs on different chromosomes in Mexicans (P < 0.00001) and Puerto Ricans (P < 0.00002) providing evidence for population substructure and/or recent admixture. To assess the effect of population stratification on association studies of asthma, we measured differences in genetic background of cases and controls by comparing allele frequencies of the 44 AIMs. Among Puerto Ricans but not in Mexicans, we observed a significant overall difference in allele frequencies between cases and controls (P = 0.0002); of 44 AIMs tested, 8 (18%) were significantly associated with asthma. However, after adjustment for individual ancestry, only two of these markers remained significantly associated with the disease. Our findings suggest that empirical assessment of the effects of stratification is critical to appropriately interpret the results of case-control studies in admixed populations.     

Recognizing Latinos’ range of skin pigment and phototypes to enhance skin cancer prevention

Latinos in the United States may have the mistaken assumption that their natural pigmentation protects them from developing skin cancer that, effectively, serves as a barrier to Latinos receiving education in primary and secondary prevention of skin cancer. Latino adults of Mexican or Puerto Rican heritage attending community health fairs in the greater Chicago area responded to a culturally informed and sensitive measure for sunburn and tan, which was previously adapted to capture skin irritation with tenderness from the sun occurring in darker skin types (n = 350). By self‐reported responses and spectrophotometry assessment of constitutive pigmentation, adapted Fitzpatrick skin types (FST) ranged from skin type I–IV in the Mexican American participants and from II to V in the Puerto Rican participants. The objectively measured proportion of adapted FST II skin type was greater than commonly perceived and demonstrated that many Latinos do indeed have sun‐sensitive skin.     

Total and Central Obesity among Elderly Hispanics and the Association with Type 2 Diabetes

Objective: To report the prevalence of total and central obesity in a representative sample of Puerto Rican and Dominican elders in Massachusetts, to compare them with a neighborhood‐based group of non‐Hispanic white elders, and to examine associations of obesity indices with the presence of type 2 diabetes. Research Methods and Procedures: We examined the prevalence of overweight, obesity, and central obesity in 596 Hispanics of Caribbean origin, ages 60 to 92 years, and 239 non‐Hispanic whites, and tested linear and logistic regression models to determine associations among body mass index (BMI), waist circumference (WC), and diabetes. Results: Obesity (BMI ≥ 30 kg/m²) was prevalent among all ethnic groups, ranging from 17% to 29% for Dominican and Puerto Rican men, respectively, and from 29% to 40% for non‐Hispanic white and Dominican women, respectively. These differences were not statistically significant. Among Hispanic men and women, diabetes was prevalent across all BMI and WC categories but tended to be greatest among those with BMI of 25 to 29 kg/m² (41% to 43%). In contrast, diabetes was most prevalent in the obese group (36% to 45%) of non‐Hispanic whites. Both BMI and WC were associated with the presence of diabetes, but the coefficients were greater for non‐Hispanic whites than for Hispanics. Discussion: Caribbean Hispanics and non‐Hispanic whites living in the same Massachusetts localities had high prevalences of overweight and obesity. Total and central obesity exerted a differential effect on the presence of diabetes among ethnic groups; for Hispanics, diabetes was prevalent even among non‐obese individuals, whereas for non‐Hispanic white women, the prevalence of diabetes was strongly associated with total and central obesity. Additional research is needed to investigate the factors associated with the differential effect of obesity on the prevalence of type 2 diabetes among Hispanic and non‐Hispanic white elders.     

Reconstructing population history using JC virus: Amerinds, Spanish, and Africans in the ancestry of modern Puerto Ricans.

The roots of the Hispanic populations of the Caribbean Islands and Central and South America go back to three continents of the Old World. In Puerto Rico major genetic contributions have come from (1) Asians in the form of the aboriginal Taino population, an Arawak tribe, present when Columbus arrived on the Island, (2) Europeans, largely Spanish explorers, settlers, government administrators, and soldiers, and (3) Africans who came as part of the slave trade. Since JC virus (JCV) genotypes characteristic of Asia, Europe, and Africa have been identified, and excretion of JCV in urine has been proposed as a marker for human migrations, we sought to characterize the JCV strains present in a Caribbean Hispanic population. We found that the strains of JCV present today in Puerto Rico are those derived from the Old World populations represented there: Types 1B and 4 from Spain, Types 3A, 3B, and 6 from Africa, and Type 2A from Asia. The Type 2A genotype represents the indigenous Taino people. This JCV genotype was represented much more frequently (61%) than would be predicted by the trihybrid model of genetic admixture. This might be attributable to characteristics of JCV Type 2A itself, as well as to the nature of the early relationships between Spanish men and native women. These findings indicate that the JCV strains carried by the Taino Indians can be found in today's Puerto Rican population despite the apparent demise of these people more than two centuries ago. Therefore, molecular characterization of JCV provides a tool to supplement genetic techniques for reconstructing population histories including admixed populations.     

Psychosocial Predictors of Metabolic Syndrome among Latino Groups in the Multi-Ethnic Study of Atherosclerosis (MESA)

Objective

We sought to determine the contribution of psychological variables to risk for metabolic syndrome (MetS) among Latinos enrolled in the Multi-Ethnic Study of Atherosclerosis (MESA), and to investigate whether social support moderates these associations, and whether inflammatory markers mediate the association between psychological variables and MetS.

Research design and methods

Cross-sectional analyses at study baseline were conducted with a national Latino cohort (n = 1,388) that included Mexican Americans, Dominican Americans, Puerto Rican Americans and Central/South Americans. Hierarchical logistic regression analyses were conducted to test the effects of psychosocial variables (chronic stress, depressive symptoms, and social support) on MetS. In addition, separate subgroup-specific models, controlling for nationality, age, gender, socioeconomic position, language spoken at home, exercise, smoking and drinking status, and testing for the effects of chronic stress, depressive symptoms and inflammation (IL-6, CRP, fibrinogen) in predicting risk for MetS were conducted.

Results

In the overall sample, high chronic stress independently predicted risk for MetS, however this association was found to be significant only in Mexican Americans and Puerto Rican Americans. Social support did not moderate the associations between chronic stress and MetS for any group. Chronic stress was not associated with inflammatory markers in either the overall sample or in each group.

Conclusions

Our results suggest a differential contribution of chronic stress to the prevalence of MetS by national groups.     

The influence of early conditions on health status among elderly Puerto Ricans

Abstract

The demographic origins of aging in Puerto Rican and other Latin American and Caribbean (LAC) countries may have important implications for the profile of health status and mortality of elderly people. For this article we tested a general conjecture about the relation between early childhood conditions and adult health status among Puerto Rican elderly using a rich data set recently collected through an island‐wide survey (N=4,293). We examined the association between markers of early nutritional status, self‐reports of health and on socioeconomic conditions during early childhood, and the prevalence of 3 conditions during adult ages: obesity, diabetes, and cardiovascular diseases. Although we found that obesity and diabetes are associated with markers of early malnutrition, that heart disease is associated with early deprivations and selected early childhood conditions, the evidence we were able to tease out from the data provides only fragile support for the conjecture.     

Ancestral proportions and their association with skin pigmentation and bone mineral density in Puerto Rican women from New York city

Hispanic and African American populations exhibit an increased risk of obesity compared with populations of European origin, a feature that may be related to inherited risk alleles from Native American and West African parental populations. However, a relationship between West African ancestry and obesity-related traits, such as body mass index (BMI), fat mass (FM), and fat-free mass (FFM), and with bone mineral density (BMD) in African American women has only recently been reported. In order to evaluate further the influence of ancestry on body composition phenotypes, we studied a Hispanic population with substantial European, West African, and Native American admixture. We ascertained a sample of Puerto Rican women living in New York (n=64), for whom we measured BMI and body composition variables, such as FM, FFM, percent body fat, and BMD. Additionally, skin pigmentation was measured as the melanin index by reflectance spectroscopy. We genotyped 35 autosomal ancestry informative markers and estimated population and individual ancestral proportions in terms of European, West African, and Native American contributions to this population. The ancestry proportions corresponding to the three parental populations are: 53.3±2.8% European, 29.1±2.3% West African, and 17.6±2.4% Native American. We detected significant genetic structure in this population with a number of different tests. A highly significant correlation was found between skin pigmentation and individual ancestry (R²=0.597, P<0.001) that was not attributable to differences in socioeconomic status. A significant association was also found between BMD and European admixture (R²=0.065, P=0.042), but no such correlation was evident with BMI or the remaining body composition measurements. We discuss the implications of our findings for the potential use of this Hispanic population for admixture mapping.