Sociocultural factors and the genetic diversification of Amazonian Indians: A brief overview

Abstract

Within SES categories in the United States, racial and ethnic minorities generally fare less well on a variety of health‐related indicators than do majority groups. Important differences exist within subgroups, however, and at present, these differences are poorly understood. In this paper we address Hispanic subgroup (Cuban American, Mexican American, Puerto Rican, and Central/South American) differences in utilization of prenatal care. Data from the 1986 and 1987 national Linked Birth/Infant Death files are used to assess patterns of prenatal care utilization across subgroups. Using Kotelchuck's Adequacy of Prenatal Care Utilization Index, we find that when controlling for other factors, Cuban American and Puerto Rican women are more likely to obtain adequate care than are Hispanic women of Mexican or Central/South American origin. Other factors important in understanding utilization patterns include marital status, education level, birthplace, and region of the country. We conclude with a discussion of the relatively weak link between prenatal care and birth outcomes and identify important cultural factors that may be important in understanding why this relationship is not stronger.     

Poverty,insurance, and well-baby care among mainland Puerto Rican children

Using data from the Puerto Rican Maternal and Infant Health Study, we investigate the implications of family income and insurance status for well-baby care among mainland Puerto Ricans. Given the socioeconomic disadvantage of Puerto Ricans, it is critical to understand the extent to which low income and lack of health insurance create barriers to well-baby care and result in low utilization. The analysis shows that the income-to-needs ratio is related to barriers to well-baby care, and a key intervening factor is insurance status. The odds of reporting any barriers to care are lowest among those with both adequate income and private health insurance. Access to insurance is also vital in achieving adequate well-baby care. Uninsured children receive inadequate care more often than children with public or private insurance, especially when their income is also low. Children with public insurance are as likely as children with private insurance to receive an adequate number of well-baby visits, despite the fact that their mothers report more barriers to care.     

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.     

Machos and Sluts: Gender, Sexuality, and Violence among a Cohort of Puerto Rican Adolescents

During the past decade, interpersonal violence increasingly has become a public health concern. As a result, prevention programs now aim to decrease violence among diverse populations. This article describes the beliefs and rationale for gender-based violence among a cohort of low-income, predominantly second-generation, mainland Puerto Rican adolescents. Based on a three-year (1989-91) ethnographic study, the findings describe how these young people, through the use of gender-based social constructs such as "machos" and "sluts," justify violence by linking it to beliefs about gender roles, sexuality, and biology, and thus perpetuate gender-role conformity, particularly heterosexual male dominance. The findings suggest that if the public health community is going to reduce gender-based violence among Puerto Rican youth, it needs to acknowledge that gender and sexuality are important ingredients that support violence and avoid a simplified and stereotypical model of culture that ignores other social factors and changes in traditional Latino gender roles.     

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.     

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.     

A Twin Study of Early-Childhood Asthma in Puerto Ricans

Background

The relative contributions of genetics and environment to asthma in Hispanics or to asthma in children younger than 3 years are not well understood.

Objective

To examine the relative contributions of genetics and environment to early-childhood asthma by performing a longitudinal twin study of asthma in Puerto Rican children ≤3 years old.

Methods

678 twin infants from the Puerto Rico Neo-Natal Twin Registry were assessed for asthma at age 1 year, with follow-up data obtained for 624 twins at age 3 years. Zygosity was determined by DNA microsatellite profiling. Structural equation modeling was performed for three phenotypes at ages 1 and 3 years: physician-diagnosed asthma, asthma medication use in the past year, and ≥1 hospitalization for asthma in the past year. Models were additionally adjusted for early-life environmental tobacco smoke exposure, sex, and age.

Results

The prevalences of physician-diagnosed asthma, asthma medication use, and hospitalization for asthma were 11.6%, 10.8%, 4.9% at age 1 year, and 34.1%, 40.1%, and 8.5% at 3 years, respectively. Shared environmental effects contributed to the majority of variance in susceptibility to physician-diagnosed asthma and asthma medication use in the first year of life (84%–86%), while genetic effects drove variance in all phenotypes (45%–65%) at age 3 years. Early-life environmental tobacco smoke, sex, and age contributed to variance in susceptibility.

Conclusion

Our longitudinal study in Puerto Rican twins demonstrates a changing contribution of shared environmental effects to liability for physician-diagnosed asthma and asthma medication use between ages 1 and 3 years. Early-life environmental tobacco smoke reduction could markedly reduce asthma morbidity in young Puerto Rican children.     

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.     

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

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.     

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.     

The Silencing of Latino Student "Voice": Puerto Rican and Mexican Narratives in Eighth Grade and High School

Narratives of 27 Puerto Rican and Mexican students, written first in eighth grade then again as juniors in high school, address the important question of "Who am I?" and illustrate school-sponsored silencing, with students' critiques of their educational experience ignored by both the elementary and the high school. The narratives also provide a window into the high dropout rates of Latino children, the reasons behind students' academic decisions, and interventions needed to change negative schooling processes and outcomes. By giving witness to these voices, we as readers help ensure that through their writing, these Latino adolescents do not just speak but that they are heard.     

Correlates of dental visits among community‐residing Latino elders: a public health alert

doi:10.1111/j.1741‐2358.2009.00335.x
Correlates of dental visits among community‐residing Latino elders: a public health alert Objectives: To examine oral service utilisation in a probability sample of community‐residing Latino elders. Background: Older Latinos are at a potential increased risk of oral diseases, given their higher prevalence of co‐morbidities and lower rate of dental service utilisation. Methods: A prevalence survey was conducted among a random sample of Latino (largely Puerto Rican) elders (n = 205; mean age = 75.8; SD ± 5.3) in New York City during 2001–2002. A systematic random sample was drawn from the Centers for Medicare and Medicaid Services Beneficiary tape files. Current use of oral health services and self‐reported health conditions was obtained. Functional and cognitive impairment were assessed. Results: Less than half of the sample reported a dental visit in the previous year. The average time since the last dental visit was 54 months (SD ± 84.5). Last year dental visit compliers were more likely to be unmarried, living alone, with higher levels of education, fewer health conditions and less impairment with activities of daily living. In multivariate analyses, problem‐oriented behaviour, Medicaid beneficiary, education, living alone, chronic health conditions and mobility impairment explained 14% of the ‘time since last dental visit’ variance. Conclusions: Given that socio‐demographic and level of functioning determinants appear to influence the frequency of dental visits, a multilevel approach to oral health promotion is imperative.     

Explaining Mental Health Treatment Disparities: Ethnic and Cultural Differences in Family Involvement

In a large, representative sample of persons receiving public mental health treatment, we examined whether ethnic minority consumers were more likely than white consumers to live with their families and to receive family support. We then evaluated whether differences observed in family involvement explained treatment disparities observed in outpatient and inpatient mental health services. Results indicated that Asian American and Latino consumers, especially, were considerably more likely than white consumers to live with family members and to receive family support. Ethnocultural differences in living with family did explain treatment intensity disparities whether or not consumers described themselves as dependent on family support. The results support the hypothesis that cultural differences in family involvement and support play a role in explaining mental health treatment disparities.     

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.     

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.     

Population admixture associated with disease prevalence in the Boston Puerto Rican health study

Older Puerto Ricans living in the continental U.S. suffer from higher rates of diabetes, obesity, cardiovascular disease and depression compared to non-Hispanic White populations. Complex diseases, such as these, are likely due to multiple, potentially interacting, genetic, environmental and social risk factors. Presumably, many of these environmental and genetic risk factors are contextual. We reasoned that racial background may modify some of these risk factors and be associated with health disparities among Puerto Ricans. The contemporary Puerto Rican population is genetically heterogeneous and originated from three ancestral populations: European settlers, native Taíno Indians, and West Africans. This rich-mixed ancestry of Puerto Ricans provides the intrinsic variability needed to untangle complex gene–environment interactions in disease susceptibility and severity. Herein, we determined whether a specific ancestral background was associated with either of four major disease outcomes (diabetes, obesity, cardiovascular disease, and depression). We estimated the genetic ancestry of 1,129 subjects from the Boston Puerto Rican Health Study based on genotypes of 100 ancestry informative markers (AIMs). We examined the effects of ancestry on tests of association between single AIMs and disease traits. The ancestral composition of this population was 57.2% European, 27.4% African, and 15.4% Native American. African ancestry was negatively associated with type 2 diabetes and cardiovascular disease, and positively correlated with hypertension. It is likely that the high prevalence rate of diabetes in Africans, Hispanics, and Native Americans is not due to genetic variation alone, but to the combined effects of genetic variation interacting with environmental and social factors. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Health care and health care seeking strategies among Puyallup Indians

This study replicated Kleinman's research on family-based popular health care in Taiwan among the Puyallup Indians of Washington. Standardized interviews were conducted among 80 Puyallup families to determine family health practices and beliefs, and the patterns of referral to professional practitioners. Comparisons are made between the Puyallup and Taiwanese family health care practices and health care seeking processes. The author concludes that the relative absence of folk medicine and the availability of free medical care among the Puyallup are the most important factors causing the variance between the rates of family treatment and the patterns of health care seeking behaviors between the Puyallup and the Taiwanese.     

Association of NOD2 and IL23R with Inflammatory Bowel Disease in Puerto Rico

The Puerto Rico population may be modeled as an admixed population with contributions from three continents: Sub-Saharan Africa, Ancient America, and Europe. Extending the study of the genetics of inflammatory bowel disease (IBD) to an admixed population such as Puerto Rico has the potential to shed light on IBD genes identified in studies of European populations, find new genes contributing to IBD susceptibility, and provide basic information on IBD for the care of US patients of Puerto Rican and Latino descent. In order to study the association between immune-related genes and Crohn’s disease (CD) and ulcerative colitis (UC) in Puerto Rico, we genotyped 1159 Puerto Rican cases, controls, and family members with the ImmunoChip. We also genotyped 832 subjects from the Human Genome Diversity Panel to provide data for estimation of global and local continental ancestry. Association of SNPs was tested by logistic regression corrected for global continental descent and family structure. We observed the association between Crohn’s disease and NOD2 (rs17313265, 0.28 in CD, 0.19 in controls, OR 1.5, p = 9×10⁻⁶) and IL23R (rs11209026, 0.026 in CD, 0.0.071 in controls, OR 0.4, p = 3.8×10⁻⁴). The haplotype structure of both regions resembled that reported for European populations and “local” continental ancestry of the IL23R gene was almost entirely of European descent. We also observed suggestive evidence for the association of the BAZ1A promoter SNP with CD (rs1200332, 0.45 in CD, 0.35 in controls, OR 1.5, p = 2×10⁻⁶). Our estimate of continental ancestry surrounding this SNP suggested an origin in Ancient America for this putative susceptibility region. Our observations underscored the great difference between global continental ancestry and local continental ancestry at the level of the individual gene, particularly for immune-related loci.     

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.