The genetic structure of populations from Haiti and Jamaica reflect divergent demographic histories

The West Indies represent an amalgamation of African, European and in some cases, East Asian sources, but the contributions from each ethnic group remain relatively unexplored from a genetic perspective. In the present study, we report, for the first time, allelic frequency data across the complete set of 15 autosomal STR loci for general collections from Haiti and Jamaica, which were subsequently used to examine the genetic diversity present in each island population. Our results indicate that although both Haiti and Jamaica display genetic affinities with the continental African collections, a stronger African signal is detected in Haiti than in Jamaica. Although only minimal contributions from non‐African sources were observed in Haiti, Jamaica displays genetic input from both European and East Asian sources, an admixture profile similar to other New World collections of African descent analyzed in this report. The divergent genetic signatures present in these populations allude to the different migratory events of Africans, Europeans, and East Asians into the New World. Am J Phys Anthropol 2010. © 2009 Wiley‐Liss, Inc.     

中国西北地区古代人群头骨的欧洲人种特征

位于中国西北部的新疆、甘肃、青海、宁夏是东亚与欧洲交汇的地区。一般认为生活在这一区域的古代人群与欧洲人群发生过融合或基因交流。但学术界对欧洲人群进入中国, 与中国古代人群发生混合与基因交流的时间、可能的扩散路线, 以及对中国现代人群形成的影响等具体细节还不是很清楚。本文对3800-1200年前生活在新疆、青海、宁夏, 以及河南安阳殷墟11个古代人群头骨呈现的欧洲人种特征进行了检测, 结果表明: 1)至少在2000-3000年前, "西方基因"已经在我国多个地区人群中存在; 2)这些"西方基因"是经由新疆向东流向内地的; 3)考古学和形态学上的证据显示欧洲人种的人群大规模地向东扩展在汉代之前的地理界限大致是在新疆的东部和甘肃的西部之间。本文所示的欧洲人种特征的出现情况, 并不受这种地理和时代的制约。     

Hereditary and environmental determinants of growth in height in a longitudinal sample of children and youth of Guatemalan and European ancestry

The effects of hereditary and environmental factors upon the growth in stature of children living in Guatemala City has been studied. Heights at yearly examinations were fitted, by individual, to a double logistic curve in samples of Guatemalan and European children attending a private school in Guatemala City. These two samples differed genetically yet shared the same environment. Their growth was compared, by a multivariate analysis of the parameterized curves, to that of children from the Berkeley Growth Study, genetically similar to the European sample, yet living in different environments. The European children in Guatemala grew, before adolescence, more similar to Guatemalan and differed significantly from the Berkeley sample children. However, the amount of growth during the adolescent years experienced by the European children was similar to that of the Berkeley sample and differed from their Guatemalan counterparts.     

Biodiversity of pig breeds from China and Europe estimated from pooled DNA samples: differences in microsatellite variation between two areas of domestication

Microsatellite diversity in European and Chinese pigs was assessed using a pooled sampling method on 52 European and 46 Chinese pig populations. A Neighbor Joining analysis on genetic distances revealed that European breeds were grouped together and showed little evidence for geographic structure, although a southern European and English group could tentatively be assigned. Populations from international breeds formed breed specific clusters. The Chinese breeds formed a second major group, with the Sino-European synthetic Tia Meslan in-between the two large clusters. Within Chinese breeds, in contrast to the European pigs, a large degree of geographic structure was noted, in line with previous classification schemes for Chinese pigs that were based on morphology and geography. The Northern Chinese breeds were most similar to the European breeds. Although some overlap exists, Chinese breeds showed a higher average degree of heterozygosity and genetic distance compared to European ones. Between breed diversity was even more pronounced and was the highest in the Central Chinese pigs, reflecting the geographically central position in China. Comparing correlations between genetic distance and heterozygosity revealed that China and Europe represent different domestication or breed formation processes. A likely cause is a more diverse wild boar population in Asia, but various other possible contributing factors are discussed.     

Y-chromosomal diversity in Haiti and Jamaica: contrasting levels of sex-biased gene flow

Although previous studies have characterized the genetic structure of populations from Haiti and Jamaica using classical and autosomal STR polymorphisms, the patrilineal influences that are present in these countries have yet to be explored. To address this lacuna, the current study aims to investigate, for the first time, the potential impact of different ancestral sources, unique colonial histories, and distinct family structures on the paternal profile of both groups. According to previous reports examining populations from the Americas, island-specific demographic histories can greatly impact population structure, including various patterns of sex-biased gene flow. Also, given the contrasting autosomal profiles provided in our earlier study (Simms et al.: Am J Phys Anthropol 142 (2010) 49-66), we hypothesize that the degree and directionality of gene flow from Europeans, Africans, Amerindians, and East Asians are dissimilar in the two countries. To test this premise, 177 high-resolution Y-chromosome binary markers and 17 Y-STR loci were typed in Haiti (n = 123) and Jamaica (n = 159) and subsequently utilized for phylogenetic comparisons to available reference collections encompassing Africa, Europe, Asia (East and South), and the New World. Our results reveal that both studied populations exhibit a predominantly South-Saharan paternal component, with haplogroups A1b-V152, A3-M32, B2-M182, E1a-M33, E1b1a-M2, E2b-M98, and R1b2-V88 comprising 77.2% and 66.7% of the Haitian and Jamaican paternal gene pools, respectively. Yet, European derived chromosomes (i.e., haplogroups G2a*-P15, I-M258, R1b1b-M269, and T-M184) were detected at commensurate levels in Haiti (20.3%) and Jamaica (18.9%), whereas Y-haplogroups indicative of Chinese [O-M175 (3.8%)] and Indian [H-M69 (0.6%) and L-M20 (0.6%)] ancestry were restricted to Jamaica.     

Growth,behaviour, and educational achievement of Jamaican children with sickle-cell trait.

A longitudinal study of the mental and physical development of 200 children with normal haemoglobin and 21 with the sickle-cell trait was carried out in a small rural community in Jamaica. At about 2 and 10 years of age heights and weights showed no significant differences. At about 10 years of age classroom behaviour, sociability, and educational achievement were similar. The results suggest that the sickle-cell trait does not affect growth and mental development.     

Screening for prolonged incubation of HTLV-I infection in British and Jamaican relatives of British patients with tropical spastic paraparesis.

OBJECTIVE--To compare the prevalence of antibody to and proviral DNA of the retrovirus HTLV-I in relatives of 11 British patients with tropical spastic paraparesis who had migrated from Jamaica before they developed symptoms, and to examine factors possibly related to transmission of HTLV-I. DESIGN--Migrant, family study. Antibody state was determined by several methods and confirmed by western blotting; the polymerase chain reaction was used to detect proviral DNA. SETTING--Britain and Jamaica. SUBJECTS--All available first degree relatives: those born and still resident in Jamaica (group 1); those born in Jamaica who migrated to Britain (group 2); and index patients'' children who were born and resident in Britain (group 3). All had been breast fed and none had had blood transfusions. RESULTS--Of the 66 living relatives, 60 were traced. Seroprevalence among those born in Jamaica (irrespective of current residence) was 22% (10/46; 95% confidence limits 9 to 34%) compared with zero among British born offspring (0/14) and was higher in group 2 at 33% (7/21; 12 to 55%) than in group 1 at 12% (3/25; 0 to 25%). (Patients in group 1 had the greatest mean age.) Proviral DNA was not detected in any subject negative for HTLV-I antibody, making prolonged viral incubation in those negative for the antibody unlikely. CONCLUSION--In this sample factors related to place of birth and early residence were more important in transmission of HTLV-I than maternal or age effects. In areas with a low to moderate prevalence policies of preventing mothers who are carriers of the virus from breast feeding would be premature.     

The Quality of Mental Health Care for African Americans

In response to the Surgeon General's request for more research on racial disparities in mental health care, especially research that includes high-need populations (e.g., the homeless, incarcerated, children in foster care, and substance abusers), we examined racial disparities in the provision of mental health counseling, psychotherapy, and pharmacotherapy in hospital outpatient settings using nationally representative data from the 1997 National Hospital Ambulatory Medical Care Survey (NHAMCS). After controlling for diagnosis and other factors, we found that African Americans were less likely than whites to receive mental health counseling and psychotherapy, but more likely than whites to receive pharmacotherapy. We also found that substance abuse clinics were more likely than primary care and specialty mental health clinics to provide mental health counseling and psychotherapy. However, specialty mental health clinics were the only clinics to provide pharmacotherapy. Future research should examine racial disparities in a variety of settings, controlling for diagnosis as well as other factors.     

Resemblance for Body Mass Index in Families of Obese African American and European American Women

Objective: We determined the levels of resemblance in body mass index (BMI) in large samples of families selected through obese African American and European American women. Research Methods and Procedures: We examined correlations among relatives in 1185 European American and African American families ascertained through age-matched obese women (BMI ≥ 30 kg/m²). A subset of 801 families were ascertained through extremely obese women (BMI ≥ 40 kg/m²). Results: Parent-offspring and sibling correlations ranged from 0.19 to 0.15, suggesting a moderate level of heritability in both groups. Mean BMI values for female relatives were lower for European Americans than for African Americans even though probands were matched, perhaps because the European American relatives regress to a lower population mean. We found significantly higher family correlations for height in European Americans, suggesting greater environmental variability among African Americans for factors affecting growth and physical development. Discussion: Our results suggest a similar level of heritability of BMI in families of obese African American and European American women. Other genetic studies will be needed to determine the extent to which the same or different genes and environmental conditions contribute to an overall similar heritability in the two racial groups.     

Differences in candidate gene association between European ancestry and African American asthmatic children

Background

Candidate gene case-control studies have identified several single nucleotide polymorphisms (SNPs) that are associated with asthma susceptibility. Most of these studies have been restricted to evaluations of specific SNPs within a single gene and within populations from European ancestry. Recently, there is increasing interest in understanding racial differences in genetic risk associated with childhood asthma. Our aim was to compare association patterns of asthma candidate genes between children of European and African ancestry.

Methodology/Principal Findings

Using a custom-designed Illumina SNP array, we genotyped 1,485 children within the Greater Cincinnati Pediatric Clinic Repository and Cincinnati Genomic Control Cohort for 259 SNPs in 28 genes and evaluated their associations with asthma. We identified 14 SNPs located in 6 genes that were significantly associated (p-values <0.05) with childhood asthma in African Americans. Among Caucasians, 13 SNPs in 5 genes were associated with childhood asthma. Two SNPs in IL4 were associated with asthma in both races (p-values <0.05). Gene-gene interaction studies identified race specific sets of genes that best discriminate between asthmatic children and non-allergic controls.

Conclusions/Significance

We identified IL4 as having a role in asthma susceptibility in both African American and Caucasian children. However, while IL4 SNPs were associated with asthma in asthmatic children with European and African ancestry, the relative contributions of the most replicated asthma-associated SNPs varied by ancestry. These data provides valuable insights into the pathways that may predispose to asthma in individuals with European vs. African ancestry.     

The Defining Moment: Children's Conceptualization of Race and Experiences with Racial Discrimination

This paper examines whether children of marginalized racial/ethnic groups have an awareness of race at earlier ages than youth from non-marginalized groups, documents their experiences with racial discrimination, and utilizes a modified racism-related stress model to explore the relationship between perceived racial discrimination and self-esteem. Data were collected for non-Hispanic black, non-Hispanic white, and Hispanic children aged 7 - 12 using face-to-face interviews (n = 175). The concept of race was measured by assessing whether children could define race, if not a standard definition was provided. Racial discrimination was measured using the Williams Every-day-Discrimination Scale, self-esteem was measured using the Rosenberg Scale, and ethnic identity was assessed using the Multi-group Ethnic Identity Measure. Non-Hispanic black children were able to define race more accurately, but overall, Hispanic children encountered more racial discrimination, with frequent reports of ethnic slurs. Additionally, after accounting for ethnic identity, perceived racial discrimination remained a salient stressor that contributed to low self-esteem.     

Mitochondrial DNA (mtDNA) haplotypes reveal maternal population genetic affinities of Sea Island Gullah-speaking African Americans

To better understand the population substructure of African Americans living in coastal South Carolina, we used restriction site polymorphisms and an insertion/deletion in mitochondrial DNA (mtDNA) to construct seven-position haplotypes across 1,395 individuals from Sierra Leone, Africa, from U.S. European Americans, and from the New World African-derived populations of Jamaica, Gullah-speaking African Americans of the South Carolina Sea Islands (Gullahs), African Americans living in Charleston, South Carolina, and West Coast African Americans. Analyses showed a high degree of similarity within the New World African-derived populations, where haplotype frequencies and diversities were similar. Phi-statistics indicated that very little genetic differentiation has occurred within New World African-derived populations, but that there has been significant differentiation of these populations from Sierra Leoneans. Genetic distance estimates indicated a close relationship of Gullahs and Jamaicans with Sierra Leoneans, while African Americans living in Charleston and the West Coast were progressively more distantly related to the Sierra Leoneans. We observed low maternal European American admixture in the Jamaican and Gullah samples (m = 0.020 and 0.064, respectively) that increased sharply in a clinal pattern from Charleston African Americans to West Coast African Americans (m = 0.099 and 0.205, respectively). The appreciably reduced maternal European American admixture noted in the Gullah indicates that the Gullah may be uniquely situated to allow genetic epidemiology studies of complex diseases in African Americans with low European American admixture.     

Place,scale and the racial claims made for multiracial children in the 1990 US Census

Multiracial children embody ambiguities inherent in racial categorization and expose fictions of discrete races. Nevertheless, parents of multiracial children were asked for the 1990 US Census to report a single race for their offspring. Using confidential 1990 Census micro-data, we investigate the choices parents made for the three most common racially mixed household types (Asian-white, black-white and Latino-white) in twelve large metropolitan areas. We find that context affects the reporting of children's racial identity. We examine these effects with models that incorporate three spatial scales: households, neighbourhoods and metropolitan areas. Model estimates reveal that racial claims made by parents of Latino- and Asian-white (but not black-white) children varied significantly across metropolitan area. A neighbourhood's proportion white increased the probability that parents reported their children as white, while a neighbourhood's racial diversity increased the probability that black-white parents claimed a non-white race (black or ‘other’) for their children.     

Comparing genetic ancestry and self-reported race/ethnicity in a multiethnic population in New York City

Self-reported race/ethnicity is frequently used in epidemiological studies to assess an individual’s background origin. However, in admixed populations such as Hispanic, self-reported race/ethnicity may not accurately represent them genetically because they are admixed with European, African and Native American ancestry. We estimated the proportions of genetic admixture in an ethnically diverse population of 396 mothers and 188 of their children with 35 ancestry informative markers (AIMs) using the STRUCTURE version 2.2 program. The majority of the markers showed significant deviation from Hardy-Weinberg equilibrium in our study population. In mothers self-identified as Black and White, the imputed ancestry proportions were 77.6% African and 75.1% European respectively, while the racial composition among self-identified Hispanics was 29.2% European, 26.0% African, and 44.8% Native American. We also investigated the utility of AIMs by showing the improved fitness of models in paraoxanase-1 genotype-phenotype associations after incorporating AIMs; however, the improvement was moderate at best. In summary, a minimal set of 35 AIMs is sufficient to detect population stratification and estimate the proportion of individual genetic admixture; however, the utility of these markers remains questionable.     

The ‘other’ looks back: racial distancing and racial alignment in migrant domestic workers' stereotypes about white and Chinese employers

While the racial and ethnic stereotyping practised by the employers of migrant domestic workers has received significant scholarly attention, these workers' racial essentializations of their employers have been largely ignored. Drawing upon interviews with Filipino migrant domestic workers in Singapore and Hong Kong, I present findings concerning the racial stereotypes these workers hold about white and Chinese employers. This stereotyping involves both racial distancing from local Chinese employers and racial alignment with expatriate white employers. This two-track racial project is a defensive tactic that allows Filipino workers to redefine themselves as occupying a higher position in the global racial order (as they see it) on cultural grounds. However, it also makes them complicit in naturalizing legacy stereotypes that valorize whites as morally and culturally superior. In addition, it encourages them to privilege the West as an idealized destination where they fantasize they will enjoy comfortable working conditions from local white employers.     

Consistent Association of Type 2 Diabetes Risk Variants Found in Europeans in Diverse Racial and Ethnic Groups

It has been recently hypothesized that many of the signals detected in genome-wide association studies (GWAS) to T2D and other diseases, despite being observed to common variants, might in fact result from causal mutations that are rare. One prediction of this hypothesis is that the allelic associations should be population-specific, as the causal mutations arose after the migrations that established different populations around the world. We selected 19 common variants found to be reproducibly associated to T2D risk in European populations and studied them in a large multiethnic case-control study (6,142 cases and 7,403 controls) among men and women from 5 racial/ethnic groups (European Americans, African Americans, Latinos, Japanese Americans, and Native Hawaiians). In analysis pooled across ethnic groups, the allelic associations were in the same direction as the original report for all 19 variants, and 14 of the 19 were significantly associated with risk. In summing the number of risk alleles for each individual, the per-allele associations were highly statistically significant (P<10⁻⁴) and similar in all populations (odds ratios 1.09–1.12) except in Japanese Americans the estimated effect per allele was larger than in the other populations (1.20; P_het = 3.8×10⁻⁴). We did not observe ethnic differences in the distribution of risk that would explain the increased prevalence of type 2 diabetes in these groups as compared to European Americans. The consistency of allelic associations in diverse racial/ethnic groups is not predicted under the hypothesis of Goldstein regarding “synthetic associations” of rare mutations in T2D.     

Investigating the Relationship between Socially-Assigned Ethnicity,Racial Discrimination and Health Advantage in New Zealand

Background

While evidence of the contribution of racial discrimination to ethnic health disparities has increased significantly, there has been less research examining relationships between ascribed racial/ethnic categories and health. It has been hypothesized that in racially-stratified societies being assigned as belonging to the dominant racial/ethnic group may be associated with health advantage. This study aimed to investigate associations between socially-assigned ethnicity, self-identified ethnicity, and health, and to consider the role of self-reported experience of racial discrimination in any relationships between socially-assigned ethnicity and health.

Methods

The study used data from the 2006/07 New Zealand Health Survey (n = 12,488), a nationally representative cross-sectional survey of adults 15 years and over. Racial discrimination was measured as reported individual-level experiences across five domains. Health outcome measures examined were self-reported general health and psychological distress.

Results

The study identified varying levels of agreement between participants'' self-identified and socially-assigned ethnicities. Individuals who reported both self-identifying and being socially-assigned as always belonging to the dominant European grouping tended to have more socioeconomic advantage and experience less racial discrimination. This group also had the highest odds of reporting optimal self-rated health and lower mean levels of psychological distress. These differences were attenuated in models adjusting for socioeconomic measures and individual-level racial discrimination.

Conclusions

The results suggest health advantage accrues to individuals who self-identify and are socially-assigned as belonging to the dominant European ethnic grouping in New Zealand, operating in part through socioeconomic advantage and lower exposure to individual-level racial discrimination. This is consistent with the broader evidence of the negative impacts of racism on health and ethnic inequalities that result from the inequitable distribution of health determinants, the harm and chronic stress linked to experiences of racial discrimination, and via the processes and consequences of racialization at a societal level.     

Estimating African American admixture proportions by use of population-specific alleles.

We analyzed the European genetic contribution to 10 populations of African descent in the United States (Maywood, Illinois; Detroit; New York; Philadelphia; Pittsburgh; Baltimore; Charleston, South Carolina; New Orleans; and Houston) and in Jamaica, using nine autosomal DNA markers. These markers either are population-specific or show frequency differences >45% between the parental populations and are thus especially informative for admixture. European genetic ancestry ranged from 6.8% (Jamaica) to 22.5% (New Orleans). The unique utility of these markers is reflected in the low variance associated with these admixture estimates (SEM 1.3%-2.7%). We also estimated the male and female European contribution to African Americans, on the basis of informative mtDNA (haplogroups H and L) and Y Alu polymorphic markers. Results indicate a sex-biased gene flow from Europeans, the male contribution being substantially greater than the female contribution. mtDNA haplogroups analysis shows no evidence of a significant maternal Amerindian contribution to any of the 10 populations. We detected significant nonrandom association between two markers located 22 cM apart (FY-null and AT3), most likely due to admixture linkage disequilibrium created in the interbreeding of the two parental populations. The strength of this association and the substantial genetic distance between FY and AT3 emphasize the importance of admixed populations as a useful resource for mapping traits with different prevalence in two parental populations.     

现代中国人群形成与分化的形态证据——中国与非洲和欧洲人群头骨非测量特征分析

现代人群形成与分化导致生活在世界不同地区的人类形成了具有明显体质特征差别的人群(或种族)。对更新世末期及全新世以来不同地理区域近代和现代人群体质特征差别、相互亲缘关系的分析是现代人群形成与分化研究的重要组成部分。本文通过对21项头骨非测量特征在近代和现代中国人群, 以及现代非洲和欧洲人群共330例标本的出现率和表现特点的观察和数据分析, 发现绝大多数特征的出现率或表现特点在三个人群间都具有不同程度的差异, 有些特征在人群间的差异甚至非常明显。与非洲及欧洲人群相比, 现代中国人头骨总体显得纤细, 眉弓、角圆枕、颧三角、颧结节等反映头骨粗壮程度的特征在现代中国人群的发育明显弱于非洲和欧洲人群。此外, 现代中国人群还具有一些明显不同于非洲和欧洲人群的头骨非测量特征, 包括锐利的眶外下缘、相对平坦的眉间鼻根点、较圆隆的颅侧壁、平坦的顶孔人字区、深弧形的上颌颧突下缘, 梯形和左右不一的鼻额-额颌缝走向等。采用判别分析可以将67.0%—79.5%的标本正确地判别归入其原来所属的组群。其中对中国人群的正确判别率分别达到70.4%和82.9%。个体标本分布显示非洲人群表现较大的分散性, 而中国和欧洲人群样本的分布明显密集集中, 提示中国和欧洲人群似乎具有更多的衍生性特征。本研究还发现多数在人群间差别显著的头骨非测量特征与头骨粗壮程度有关, 作者对相关的问题进行了分析探讨。