Ancestry Articles

The DNA ancestry testing industry is more than a decade old, yet details about it remain a mystery: there remain no reliable, empirical data on the number, motivations, and attitudes of customers to date, the number of products available and their characteristics, or the industry customs and standard practices that have emerged in the absence of specific governmental regulations. Here, we provide preliminary data collected in 2009 through indirect and direct participant observation, namely blog post analysis, generalized survey analysis, and targeted survey analysis. The attitudes include the first available data on attitudes of those of individuals who have and have not had their own DNA ancestry tested as well as individuals who are members of DNA ancestry-related social networking groups. In a new and fluid landscape, the results highlight the need for empirical data to guide policy discussions and should be interpreted collectively as an invitation for additional investigation of (1) the opinions of individuals purchasing these tests, individuals obtaining these tests through research participation, and individuals not obtaining these tests; (2) the psychosocial and behavioral reactions of individuals obtaining their DNA ancestry information with attention given both to expectations prior to testing and the sociotechnical architecture of the test used; and (3) the applications of DNA ancestry information in varying contexts.

Post-Human Genome Project progress has enabled a new wave of population genetic research, and intensified controversy over the use of race/ethnicity in this work. At the same time, the development of methods for inferring genetic ancestry offers more empirical means of assigning group labels. Here, we provide a systematic analysis of the use of race/ethnicity and ancestry in current genetic research. We base our analysis on key published recommendations for the use and reporting of race/ethnicity which advise that researchers: explain why the terms/categories were used and how they were measured, carefully define them, and apply them consistently. We studied 170 population genetic research articles from high impact journals, published 2008–2009. A comparative perspective was obtained by aligning study metrics with similar research from articles published 2001–2004. Our analysis indicates a marked improvement in compliance with some of the recommendations/guidelines for the use of race/ethnicity over time, while showing that important shortfalls still remain: no article using ‘race’, ‘ethnicity’ or ‘ancestry’ defined or discussed the meaning of these concepts in context; a third of articles still do not provide a rationale for their use, with those using ‘ancestry’ being the least likely to do so. Further, no article discussed potential socio-ethical implications of the reported research. As such, there remains a clear imperative for highlighting the importance of consistent and comprehensive reporting on human populations to the genetics/genomics community globally, to generate explicit guidelines for the uses of ancestry and genetic ancestry, and importantly, to ensure that guidelines are followed.

During the last few years a large number of companies have emerged offering DNA testing via the Internet “direct-to-consumer”. In this paper, I analyse the rhetoric appeal to personal identity put forward on the websites of some of these consumer genomics companies. The investigation is limited to non-health-related DNA testing and focuses on individualistic and communitarian—in a descriptive sense—visions of identity. The individualistic visions stress that each individual is unique and suggest that this uniqueness can be supported by, for example, DNA fingerprinting. The communitarian visions emphasise that individuals are members of communities, in this case genetic communities. It is suggested that these visions can be supported by, for example, various types of tests for genetic ancestry tracing. The main part of the paper is devoted to an analysis of these communitarian visions of identity and the DNA tests they refer to.

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.

This article was reviewed by Rob Knight, Robert Beiko (nominated by Peter Gogarten), and Michael Gilchrist.

Ancestry inference based on autosomal markers remains a niche approach in forensic analysis: most laboratories feel more secure with a review of the cumulative STR profile frequencies in a range of relevant populations with the possible additional analysis of mitochondrial and/or Y-chromosome variability. However, a proportion of autosomal single nucleotide polymorphisms (SNPs) show very well-differentiated allele frequencies among global population-groups. Furthermore, such ancestry informative marker SNPs (AIM-SNPs) lend themselves to relatively straightforward typing with short-amplicon PCR and multiplexed single base extension reactions using the same capillary electrophoresis detectors required for the sequencing and STR genotyping of mainstream forensic markers. In this chapter, we describe a 34 AIM-SNP multiplex that is robust enough for the analysis of challenging, often highly degraded DNA typical of much of routine forensic casework. We also outline in detail the in-silico procedures necessary for collecting parental population reference data from the SPSmart SNP databases and performing ancestry inference of single AIM-SNP profiles or large-scale population data using the companion ancestry analysis website of . Two casework examples are described that show, in both cases, that an inference of likely ancestry using AIM-SNPs helped the identification of highly degraded skeletal material.

Ancestry informative markers (AIMs) are genetic loci showing alleles with large frequency differences between populations. AIMs can be used to estimate biogeographical ancestry at the level of the population, subgroup (e.g. cases and controls) and individual. Ancestry estimates at both the subgroup and individual level can be directly instructive regarding the genetics of the phenotypes that differ qualitatively or in frequency between populations. These estimates can provide a compelling foundation for the use of admixture mapping (AM) methods to identify the genes underlying these traits. We present details of a panel of 34 AIMs and demonstrate how such studies can proceed, by using skin pigmentation as a model phenotype. We have genotyped these markers in two population samples with primarily African ancestry, viz. African Americans from Washington D.C. and an African Caribbean sample from Britain, and in a sample of European Americans from Pennsylvania. In the two African population samples, we observed significant correlations between estimates of individual ancestry and skin pigmentation as measured by reflectometry (R=0.21,<0.0001 for the African-American sample and R=0.16,<0.0001 for the British African-Caribbean sample). These correlations confirm the validity of the ancestry estimates and also indicate the high level of population structure related to admixture, a level that characterizes these populations and that is detectable by using other tests to identify genetic structure. We have also applied two methods of admixture mapping to test for the effects of three candidate genes (,,) on pigmentation. We show that and have measurable effects on skin pigmentation differences between the west African and west European parental populations. This work indicates that it is possible to estimate the individual ancestry of a person based on DNA analysis with a reasonable number of well-defined genetic markers. The implications and applications of ancestry estimates in biomedical research are discussed.

Little is known about the lay public’s awareness and attitudes concerning genetic testing and what factors influence their perspectives. The existing literature focuses mainly on ethnic and socioeconomic differences; however, here we focus on how awareness and attitudes regarding genetic testing differ by geographical regions in the US. We compared awareness and attitudes concerning genetic testing for disease risk and ancestry among 452 adults (41% Black and 67% female) in four major US cities, Norman, OK; Cincinnati, OH; Harlem, NY; and Washington, DC; prior to their participation in genetic ancestry testing. The OK participants reported more detail about their personal ancestries ( = 0.02) and valued ancestry testing over disease testing more than all other sites ( < 0.01). The NY participants were more likely than other sites to seek genetic testing for disease ( = 0.01) and to see benefit in finding out more about one’s ancestry ( = 0.02), while the DC participants reported reading and hearing more about genetic testing for African ancestry than all other sites ( < 0.01). These site differences were not better accounted for by sex, age, education, self-reported ethnicity, religion, or previous experience with genetic testing/counseling. Regional differences in awareness and attitudes transcend traditional demographic predictors, such as ethnicity, age and education. Local sociocultural factors, more than ethnicity and socioeconomic status, may influence the public’s awareness and belief systems, particularly with respect to genetics.

The Noir Marron are unique in having conserved their African genetic ancestry, despite major cultural exchanges with Amerindians and Europeans through inhabiting the same region for four centuries. Their maroon identity and the important number of slaves deported in this region have maintained the original African diversity. All these characteristics permit to identify a major origin located in the former region of the Gold Coast and the Bight of Benin; regions highly impacted by slavery, from which goes a sex-biased longitudinal gradient of ancestry.

Adipocytokines are a subset of cytokines produced by adipose tissue and are associated with risk of type II diabetes and atherosclerosis. Levels of adipocytokines differ between Black and White Americans, even after adjustment for differences in adiposity, diseases associated with adipocytokines including type 2 diabetes and cardiovascular disease, and general socioeconomic status indicators such as income. We used a series of ancestry informative markers to estimate genetic ancestry in a population-based study of older Black Americans, and examined the association between genetic ancestry and adipocytokines and soluble receptors to help determine which of these may be most amenable to admixture mapping. We typed 35 ancestry informative markers in 1,241 self-reported Black Americans with available DNA from the Health, Aging, and Body Composition (Health ABC) study with available DNA and used a maximum likelihood approach to estimate percent European ancestry. We used linear regression models to determine the association between these adipocytokines and percent ancestry, and staged models to examine whether adiposity or other measures affected the associations of genetic ancestry and adipocytokines. Mean European ancestry was 22.3 ± 15.9%. In multivariate adjusted models, the strongest associations observed were between higher European ancestry and interleukin-6 soluble receptor (IL-6 SR), C-reactive protein (CRP), and adiponectin levels, with interleukin-2 soluble receptor (IL-2 SR) and soluble tumor necrosis factor receptor II (TNF-? SR II) also showing more modest but significant associations. The association with adiponectin became stronger after adjustment for adiposity. These novel findings suggest that admixture mapping may identify genetic factors influencing the levels of IL-6 SR, CRP, IL-2 SR, and adiponectin.

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