Ancestry Informative Markers (ancestry + informative_marker)

Distribution by Scientific Domains

Selected Abstracts

Blood group O alleles in Native Americans: Implications in the peopling of the Americas

Benito Estrada-Mena
Abstract All major ABO blood alleles are found in most populations worldwide, whereas the majority of Native Americans are nearly exclusively in the O group. O allele molecular characterization could aid in elucidating the possible causes of group O predominance in Native American populations. In this work, we studied exon 6 and 7 sequence diversity in 180 O blood group individuals from four different Mesoamerican populations. Additionally, a comparative analysis of genetic diversity and population structure including South American populations was performed. Results revealed no significant differences among Mesoamerican and South American groups, but showed significant differences within population groups attributable to previously detected differences in genetic drift and founder effects throughout the American continent. Interestingly, in all American populations, the same set of haplotypes O1, O1v, and O1v(G542A) was present, suggesting the following: (1) that they constitute the main genetic pool of the founding population of the Americas and (2) that they derive from the same ancestral source, partially supporting the single founding population hypothesis. In addition, the consistent and restricted presence of the G542A mutation in Native Americans compared to worldwide populations allows it to be employed as an Ancestry informative marker (AIM). Present knowledge of the peopling of the Americas allows the prediction of the way in which the G542A mutation could have emerged in Beringia, probably during the differentiation process of Asian lineages that gave rise to the founding population of the continent. Am J Phys Anthropol, 2010. 2009 Wiley-Liss, Inc. [source]

A panel of ancestry informative markers for estimating individual biogeographical ancestry and admixture from four continents: utility and applications,

HUMAN MUTATION, Issue 5 2008
Indrani Halder
Abstract Autosomal ancestry informative markers (AIMs) are useful for inferring individual biogeographical ancestry (I-BGA) and admixture. Ancestry estimates obtained from Y and mtDNA are useful for reconstructing population expansions and migrations in our recent past but individual genomic admixture estimates are useful to test for association of admixture with phenotypes, as covariate in association studies to control for stratification and, in forensics, to estimate certain overt phenotypes from ancestry. We have developed a panel of 176 autosomal AIMs that can effectively distinguish I-BGA and admixture proportions from four continental ancestral populations: Europeans, West Africans, Indigenous Americans, and East Asians. We present allele frequencies for these AIMs in all four ancestral populations and use them to assess the global apportionment of I-BGA and admixture diversity among some extant populations. We observed patterns of apportionment similar to those described previously using sex and autosomal markers, such as European admixture for African Americans (14.3%) and Mexicans (43.2%), European (65.5%) and East Asian affiliation (27%) for South Asians, and low levels of African admixture (2.8,10.8%) mirroring the distribution of Y E3b haplogroups among various Eurasian populations. Using simulation studies and pedigree analysis we show that I-BGA estimates obtained using this panel and a four-population model has a high degree of precision (average root mean square error [RMSE]=0.026). Using ancestry,phenotype associations we demonstrate that a large and informative AIM panel such as this can help reduce false-positive and false-negative associations between phenotypes and admixture proportions, which may result when using a smaller panel of less informative AIMs. Hum Mutat 29(5), 648,658, 2008. 2008 Wiley-Liss, Inc. [source]

Genetic admixture, self-reported ethnicity, self-estimated admixture, and skin pigmentation among Hispanics and Native Americans

Yann C. Klimentidis
Abstract The relationship between ethnicity and biology is of interest to anthropologists, biomedical scientists, and historians in understanding how human groups are constructed. Ethnic self-identification in recently admixed groups such as Hispanics, African Americans, and Native Americans (NA) is likely to be complex due to the heterogeneity in individual admixture proportions and social environments within these groups. This study examines the relationships between self-identified ethnicity, self-estimated admixture proportions, skin pigmentation, and genetic marker estimated admixture proportions. These measures were assessed using questionnaires, skin color measurements, and genotyping of a panel of 76 ancestry informative markers, among 170 Hispanics and NAs from New Mexico, a state known for its complex history of interactions between people of NA and European (EU) ancestry. Results reveal that NAs underestimate their degree of EU admixture, and that Hispanics underestimate their degree of NA admixture. Within Hispanics, genetic-marker estimated admixture is better predicted by forehead skin pigmentation than by self-estimated admixture. We also find that Hispanic individuals self-identified as "half-White, half Hispanic" and "Spanish" have lower levels of NA admixture than those self-identified as "Mexican" and "Mexican American." Such results highlight the interplay between culture and biology in how individuals identify and view themselves, and have implications for how ethnicity and disease risk are assessed in a medical setting. Am J Phys Anthropol, 2009. 2008 Wiley-Liss, Inc. [source]

European population substructure is associated with mucocutaneous manifestations and autoantibody production in systemic lupus erythematosus

Sharon A. Chung
Objective To determine whether genetic substructure in European-derived populations is associated with specific manifestations of systemic lupus erythematosus (SLE), including mucocutaneous phenotypes, autoantibody production, and renal disease. Methods SLE patients of European descent (n = 1,754) from 8 case collections were genotyped for >1,400 ancestry informative markers that define a north,south gradient of European substructure. Using the Structure program, each SLE patient was characterized in terms of percent Northern (versus percent Southern) European ancestry based on these genetic markers. Nonparametric methods, including tests for trend, were used to identify associations between Northern European ancestry and specific SLE manifestations. Results In multivariate analyses, increasing levels of Northern European ancestry were significantly associated with photosensitivity (Ptrend = 0.0021, odds ratio for highest quartile of Northern European ancestry versus lowest quartile [ORhigh,low] 1.64, 95% confidence interval [95% CI] 1.13,2.35) and discoid rash (Ptrend = 0.014, ORhigh,low 1.93, 95% CI 0.98,3.83). In contrast, increasing levels of Northern European ancestry had a protective effect against the production of anticardiolipin autoantibodies (Ptrend = 1.6 10,4, ORhigh,low 0.46, 95% CI 0.30,0.69) and anti,double-stranded DNA autoantibodies (Ptrend = 0.017, ORhigh,low 0.67, 95% CI 0.46,0.96). Conclusion This study demonstrates that specific SLE manifestations vary according to Northern versus Southern European ancestry. Thus, genetic ancestry may contribute to the clinical heterogeneity and variation in disease outcomes among SLE patients of European descent. Moreover, these results suggest that genetic studies of SLE subphenotypes will need to carefully address issues of population substructure based on genetic ancestry. [source]