共查询到20条相似文献，搜索用时 0 毫秒
1.
Seldin MF Tian C Shigeta R Scherbarth HR Silva G Belmont JW Kittles R Gamron S Allevi A Palatnik SA Alvarellos A Paira S Caprarulo C Guillerón C Catoggio LJ Prigione C Berbotto GA García MA Perandones CE Pons-Estel BA Alarcon-Riquelme ME 《American journal of physical anthropology》2007,132(3):455-462
Argentine population genetic structure was examined using a set of 78 ancestry informative markers (AIMs) to assess the contributions of European, Amerindian, and African ancestry in 94 individuals members of this population. Using the Bayesian clustering algorithm STRUCTURE, the mean European contribution was 78%, the Amerindian contribution was 19.4%, and the African contribution was 2.5%. Similar results were found using weighted least mean square method: European, 80.2%; Amerindian, 18.1%; and African, 1.7%. Consistent with previous studies the current results showed very few individuals (four of 94) with greater than 10% African admixture. Notably, when individual admixture was examined, the Amerindian and European admixture showed a very large variance and individual Amerindian contribution ranged from 1.5 to 84.5% in the 94 individual Argentine subjects. These results indicate that admixture must be considered when clinical epidemiology or case control genetic analyses are studied in this population. Moreover, the current study provides a set of informative SNPs that can be used to ascertain or control for this potentially hidden stratification. In addition, the large variance in admixture proportions in individual Argentine subjects shown by this study suggests that this population is appropriate for future admixture mapping studies. 相似文献
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Bonilla C Gutiérrez G Parra EJ Kline C Shriver MD 《American journal of physical anthropology》2005,128(4):861-869
We studied 156 individuals of Native American descent from the city of Tlapa in the state of Guerrero in western Mexico. Most individuals' ethnicity was either Nahua, Mixtec, or Tlapanec, but self-identified Mestizos and individuals of mixed ethnicities were also included in the sample. We typed 24 autosomal, one Y-chromosome, and four mitochondrial ancestry-informative markers (AIMs) to estimate group and individual admixture proportions, and determine whether the admixture process involved directional gene flow between parental groups. When genetically defined (GD) Mestizos were excluded from the analysis, Native American ancestry represented approximately 98% of the population's gene pool, while European and West African ancestry represented approximately 1% each. Maternally inherited markers also showed an exceptionally high Native American contribution (98.5%), as did the paternally inherited marker, DYS199 (90.7%). We did not detect genetic structure in this population using these AIMs, which appears consistent with the homogeneity of the sample in terms of admixture proportions. The addition of GD Mestizos to the sample did not produce a considerable change in admixture estimates, but it had a major effect on population structure. These results show that the population of Tlapa in Guerrero, Mexico, has experienced little admixture with Europeans and/or West Africans. They also show that the impact of a small number of admixed individuals on an otherwise homogeneous population might have profound implications on subsequent ancestry/phenotype analysis and mapping strategies. We suggest that heterogeneity is a major characteristic of Mexican populations and, as a consequence, should not be disregarded when designing epidemiological studies of Mexican and Mexican American populations. 相似文献
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Jos R. Fernndez Mark D. Shriver T. Mark Beasley Nashwa Rafla‐Demetrious Esteban Parra Jeanine Albu Barbara Nicklas Alice S. Ryan Paul M. McKeigue Clive L. Hoggart Roland L. Weinsier David B. Allison 《Obesity (Silver Spring, Md.)》2003,11(7):904-911
Objective: To investigate the role of genetic admixture in explaining phenotypic variation in obesity‐related traits in a sample of African‐American women (n = 145) and to determine significant associations between obesity traits and admixture genetic markers. Research Methods and Procedures: Associations between genetic admixture and BMI, resting metabolic rate, fat mass, fat‐free mass, and bone mineral density were tested using linear regression considering the estimation of admixture by 1) a maximum‐likelihood approach (MLA) and 2) a Bayesian analysis. Results: Both the conservative MLA and the Bayesian approach support an association between African genetic admixture and BMI. Evidence for the associations of African genetic admixture with fat mass and fat‐free mass was supported by the Bayesian analysis; the MLA supported an association with bone mineral density. When the individual ancestry informative markers that were used to estimate admixture were tested for associations with BMI, significant associations were identified in chromosomes 1, 11, and 12. Discussion: These results provide evidence supporting the application of admixture mapping methods to the identification of genes that result in higher levels of obesity among African‐American women. Further research is needed to replicate and further explore these findings. 相似文献
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Naama M. Kopelman Jonathan Mayzel Mattias Jakobsson Noah A. Rosenberg Itay Mayrose 《Molecular ecology resources》2015,15(5):1179-1191
The identification of the genetic structure of populations from multilocus genotype data has become a central component of modern population‐genetic data analysis. Application of model‐based clustering programs often entails a number of steps, in which the user considers different modelling assumptions, compares results across different predetermined values of the number of assumed clusters (a parameter typically denoted K), examines multiple independent runs for each fixed value of K, and distinguishes among runs belonging to substantially distinct clustering solutions. Here, we present Clumpak (Cluster Markov Packager Across K), a method that automates the postprocessing of results of model‐based population structure analyses. For analysing multiple independent runs at a single K value, Clumpak identifies sets of highly similar runs, separating distinct groups of runs that represent distinct modes in the space of possible solutions. This procedure, which generates a consensus solution for each distinct mode, is performed by the use of a Markov clustering algorithm that relies on a similarity matrix between replicate runs, as computed by the software Clumpp . Next, Clumpak identifies an optimal alignment of inferred clusters across different values of K, extending a similar approach implemented for a fixed K in Clumpp and simplifying the comparison of clustering results across different K values. Clumpak incorporates additional features, such as implementations of methods for choosing K and comparing solutions obtained by different programs, models, or data subsets. Clumpak , available at http://clumpak.tau.ac.il , simplifies the use of model‐based analyses of population structure in population genetics and molecular ecology. 相似文献
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Identification of population structure can help trace population histories and identify disease genes. Structured association (SA) is a commonly used approach for population structure identification and association mapping. A major issue with SA is that its performance greatly depends on the informativeness and the numbers of ancestral informative markers (AIMs). Present major AIM selection methods mostly require prior individual ancestry information, which is usually not available or uncertain in practice. To address this potential weakness, we herein develop a novel approach for AIM selection based on principle component analysis (PCA), which does not require prior ancestry information of study subjects. Our simulation and real genetic data analysis results suggest that, with equivalent AIMs, PCA-based selected AIMs can significantly increase the accuracy of inferred individual ancestries compared with traditionally randomly selected AIMs. Our method can easily be applied to whole genome data to select a set of highly informative AIMs in population structure, which can then be used to identify potential population structure and correct possible statistical biases caused by population stratification. 相似文献
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Gravel S 《Genetics》2012,191(2):607-619
Migrations have played an important role in shaping the genetic diversity of human populations. Understanding genomic data thus requires careful modeling of historical gene flow. Here we consider the effect of relatively recent population structure and gene flow and interpret genomes of individuals that have ancestry from multiple source populations as mosaics of segments originating from each population. This article describes general and tractable models for local ancestry patterns with a focus on the length distribution of continuous ancestry tracts and the variance in total ancestry proportions among individuals. The models offer improved agreement with Wright-Fisher simulation data when compared to the state-of-the art and can be used to infer time-dependent migration rates from multiple populations. Considering HapMap African-American (ASW) data, we find that a model with two distinct phases of European gene flow significantly improves the modeling of both tract lengths and ancestry variances. 相似文献
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Katherine S Elliott Marc Haber Hinda Daggag George B Busby Rizwan Sarwar Derek Kennet Michael Petraglia Lawrence J Petherbridge Parisa Yavari Frauke U Heard-Bey Bindu Shobi Tariq Ghulam Dalia Haj Alia Al Tikriti Alshafi Mohammad Suma Antony Maitha Alyileili Shatha Alaydaroos Evelyn Lau Mark Butler Arash Yavari Julian C Knight Houman Ashrafian Maha T Barakat 《Molecular biology and evolution》2022,39(3)
The indigenous population of the United Arab Emirates (UAE) has a unique demographic and cultural history. Its tradition of endogamy and consanguinity is expected to produce genetic homogeneity and partitioning of gene pools while population movements and intercontinental trade are likely to have contributed to genetic diversity. Emiratis and neighboring populations of the Middle East have been underrepresented in the population genetics literature with few studies covering the broader genetic history of the Arabian Peninsula. Here, we genotyped 1,198 individuals from the seven Emirates using 1.7 million markers and by employing haplotype-based algorithms and admixture analyses, we reveal the fine-scale genetic structure of the Emirati population. Shared ancestry and gene flow with neighboring populations display their unique geographic position while increased intra- versus inter-Emirati kinship and sharing of uniparental haplogroups, reflect the endogamous and consanguineous cultural traditions of the Emirates and their tribes. 相似文献
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在复杂疾病的全基因组关联研究中,人群分层现象会增加结果的假阳性率,因此考虑人群遗传结构、控制人群分层是很有必要的。而在人群分层研究中,使用随机选择的SNP的效果还有待进一步探讨。文章利用HapMap Phase2人群中无关个体的Affymetrix SNP 6.0芯片分型数据,在全基因组上随机均匀选择不同数量的SNP,同时利用f值和Fisher精确检验方法筛选祖先信息标记（Ancestry Informative Markers,AIMs）。然后利用HapMap Phase3中的无关个体的数据,以F-statistics和STRUCTURE分析两种方法评估所选出的不同SNP组合对人群的区分效果。研究发现,随机均匀分布于全基因组的SNP可用于识别人群内部存在的遗传结构。文章进一步提示,在全基因组关联研究中,当没有针对特定人群的AIMs时,可在全基因组上随机选择3000以上均匀分布的SNP来控制人群分层。 相似文献
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Model based methods for genetic clustering of individuals, such as those implemented in structure or ADMIXTURE, allow the user to infer individual ancestries and study population structure. The underlying model makes several assumptions about the demographic history that shaped the analysed genetic data. One assumption is that all individuals are a result of K homogeneous ancestral populations that are all well represented in the data, while another assumption is that no drift happened after the admixture event. The histories of many real world populations do not conform to that model, and in that case taking the inferred admixture proportions at face value might be misleading. We propose a method to evaluate the fit of admixture models based on estimating the correlation of the residual difference between the true genotypes and the genotypes predicted by the model. When the model assumptions are not violated, the residuals from a pair of individuals are not correlated. In the case of a bad fitting admixture model, individuals with similar demographic histories have a positive correlation of their residuals. Using simulated and real data, we show how the method is able to detect a bad fit of inferred admixture proportions due to using an insufficient number of clusters K or to demographic histories that deviate significantly from the admixture model assumptions, such as admixture from ghost populations, drift after admixture events and nondiscrete ancestral populations. We have implemented the method as an open source software that can be applied to both unphased genotypes and low depth sequencing data. 相似文献
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本文基于插入-缺失多态性(insertion-deletion polymorphism,InDel)遗传标记,从相关文献和dbSNP库中筛选出38个在东亚、欧洲、非洲人群中具有等位基因频率差异的祖先来源InDel位点,同时整合Amelogenin位点和Y染色体STR(DYS439)位点,以辅助未知样本的性别鉴定,采用PCR-CE技术构建了可以区分三大洲际人群的单管直接扩增复合检测体系,该体系可与微流控芯片系统相结合,1.7 h内完成DNA样本自动化扩增和电泳分型,利用公共数据库1000Genomes中16个人群1 607名个体的分型数据对筛选的38个InDel位点进行初步评估;同时对构建的38-plex InDels体系的灵敏度、准确性、直接扩增能力进行验证评估;检测5种不同人群的779份样本和215份唾液卡、血卡的直接扩增样本,采用聚类分析和主成分分析方法,评价体系的推断准确性.结果表明该38-plex InDels复合检测体系分型准确,灵敏度达157 pg,能够对唾液卡和血卡直接扩增,可以区分三大洲际人群及其混合人群,能够准确推断待测样本的族群来源、估算祖先成分,且通过集成细胞裂解步骤将有望2h实现\"样本进-结果出\"式快速自动化InDel分型. 相似文献
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Noah A. Rosenberg 《Molecular ecology resources》2004,4(1):137-138
In analysis of multilocus genotypes from structured populations, individual coefficients of membership in subpopulations are often estimated using programs such as structure . distruct provides a general method for visualizing these estimated membership coefficients. Subpopulations are represented as colours, and individuals are depicted as bars partitioned into coloured segments that correspond to membership coefficients in the subgroups. distruct , available at http://www.cmb.usc.edu/~noahr/distruct.html , can also be used to display subpopulation assignment probabilities when individuals are assumed to have ancestry in only one group. 相似文献
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Jinliang Wang 《Molecular ecology resources》2017,17(5):981-990
The computer program Structure implements a Bayesian method, based on a population genetics model, to assign individuals to their source populations using genetic marker data. It is widely applied in the fields of ecology, evolutionary biology, human genetics and conservation biology for detecting hidden genetic structures, inferring the most likely number of populations (K), assigning individuals to source populations and estimating admixture and migration rates. Recently, several simulation studies repeatedly concluded that the program yields erroneous inferences when samples from different populations are highly unbalanced in size. Analysing both simulated and empirical data sets, this study confirms that Structure indeed yields poor individual assignments to source populations and gives frequently incorrect estimates of K when sampling is unbalanced. However, this poor performance is mainly caused by the adoption of the default ancestry prior, which assumes all source populations contribute equally to the pooled sample of individuals. When the alternative ancestry prior, which allows for unequal representations of the source populations by the sample, is adopted, accurate individual assignments could be obtained even if sampling is highly unbalanced. The alternative prior also improves the inference of K by two estimators, albeit the improvement is not as much as that in individual assignments to populations. For the difficult case of many populations and unbalanced sampling, a rarely used parameter combination of the alternative ancestry prior, an initial ALPHA value much smaller than the default and the uncorrelated allele frequency model is required for Structure to yield accurate inferences. I conclude that Structure is easy to use but is easier to misuse because of its complicated genetic model and many parameter (prior) options which may not be obvious to choose, and suggest using multiple plausible models (parameters) and K estimators in conducting comparative and exploratory Structure analysis. 相似文献
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We characterize 20 single nucleotide polymorphism assays for evaluating hybridization between native golden trout subspecies (Oncorhynchus mykiss aguabonita and O. m. whitei) and introduced rainbow trout strains. These assays utilize the 5′‐nuclease reaction, facilitating high‐throughput genotyping of many individuals and making them useful in quantifying and monitoring introgression and potentially applicable to studies of other O. mykiss groups. Minor allele frequency differentials (δq) among native and introduced rainbow groups ranged from 0 to 1, with an average differential of 0.75 for both subspecies aguabonita and whitei relative to the hatchery rainbow trout strain. 相似文献
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Raquel Godinho José Vicente López‐Bao Diana Castro Luís Llaneza Susana Lopes Pedro Silva Nuno Ferrand 《Molecular ecology resources》2015,15(2):317-328
Wolves and dogs provide a paradigmatic example of the ecological and conservation implications of hybridization events between wild and domesticated forms. However, our understanding of such implications has been traditionally hampered by both high genetic similarity and the difficulties in obtaining tissue samples (TS), which limit our ability to assess ongoing hybridization events. To assess the occurrence and extension of hybridization in a pack of wolf–dog hybrids in northwestern Iberia, we compared the power of 52 nuclear markers implemented on TS with a subset of 13 ancestry informative markers (AIMs) typed in noninvasive samples (NIS). We demonstrate that the 13 AIMs are as accurate as the 52 markers that were chosen without regard to the power to differentiate between wolves and dogs, also having the advantage of being rapidly screened on NIS. The efficiency of AIMs significantly outperformed ten random sets of similar size and an additional commercial set of 18 markers. Bayesian clustering analysis implemented on AIMs and NIS identified nine hybrids, two wolves and two dogs. Four hybrids were unambiguously assigned to F1xWolf backcrosses. Our approach (AIMs + NIS) overcomes previous difficulties related to sample availability and informative power of markers, allowing a quick identification of wolf–dog hybrids in the first phases of hybridization episodes. This provides managers with a reliable tool to evaluate hybridization and estimate the success of their actions. This approach may be easily adapted for other pairs of wild/domesticated species, thus improving our understanding of the introgression of domestication genes into natural populations. 相似文献
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Fernando A. Villanea Deborah A. Bolnick Cara Monroe Rosita Worl Rosemary Cambra Alan Leventhal Brian M. Kemp 《American journal of physical anthropology》2013,151(4):649-657
In this study, we explore the geographic and temporal distribution of a unique variant of the O blood group allele called O1vG542A, which has been shown to be shared among Native Americans but is rare in other populations. O1vG542A was previously reported in Native American populations in Mesoamerica and South America, and has been proposed as an ancestry informative marker. We investigated whether this allele is also found in the Tlingit and Haida, two contemporary indigenous populations from Alaska, and a pre‐Columbian population from California. If O1vG542A is present in Na‐Dene speakers (i.e., Tlingits), it would indicate that Na‐Dene speaking groups share close ancestry with other Native American groups and support a Beringian origin of the allele, consistent with the Beringian Incubation Model. If O1vG542A is found in pre‐Columbian populations, it would further support a Beringian origin of the allele, rather than a more recent introduction of the allele into the Americas via gene flow from one or more populations which have admixed with Native Americans over the past five centuries. We identified this allele in one Na‐Dene population at a frequency of 0.11, and one ancient California population at a frequency of 0.20. Our results support a Beringian origin of O1vG542A, which is distributed today among all Native American groups that have been genotyped in appreciable numbers at this locus. This result is consistent with the hypothesis that Na‐Dene and other Native American populations primarily derive their ancestry from a single source population. Am J Phys Anthropol 151:649–657, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
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