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Admixed Population (admixed + population)
Selected AbstractsUsing Genetic Admixture to Study the Biology of Obesity Traits and to Map Genes in Admixed PopulationsNUTRITION REVIEWS, Issue 2004José R. Fernández Ph.D. Differences among ethnic and racial groups in obesity-related traits have been clearly established in the scientific literature. To explore the genetic component underlying these differences, the genetic admixture approach has been used. In this approach, ancestry informative genetic markers are used to estimate a quantitative value representing the degree of ancestral background in individuals of admixed genetic background. Genetic admixture has been successfully used to explain racial and ethnic variation in obesity related traits; however, the understanding and measure of cultural and environmental components that also influence these phenotypes still requires further exploration [source] CYP1A1 variants and smoking-related lung cancer in San Francisco bay area Latinos and African AmericansINTERNATIONAL JOURNAL OF CANCER, Issue 1 2005Margaret R. Wrensch Abstract We examined CYP1A1 T6235C (M1) and A4889G (M2) polymorphisms in San Francisco Bay Area African Americans and Latinos who were newly diagnosed with primary lung cancer from September 1998 to November 2002 and in age-gender-ethnicity frequency-matched controls. Owing mainly to rapid mortality of cases, overall percentages of cases genotyped were 26% and 32% for Latinos and African Americans, respectively. CYP1A1 variants were genotyped for Latinos (104 cases, 278 controls) and African Americans (226 cases, 551 controls). M1 and M2 frequencies in controls were 0.23 and 0.02 for African Americans and 0.38 and 0.29 for Latinos. In Latinos, the overall inverse odds ratio (OR) of 0.51 (95% CI = 0.32,0.81) for M1 variant genotype resulted from an inverse interaction with smoking. Nonsmokers with M1 genotype had a slight elevated OR (1.5; 0.59,3.7), but those with less than 30 or 30 or more pack-year history had 0.20 (0.06,0.70) and 0.21 (0.06,0.81) times (about 1/5) the odds expected if smoking and genotype were independent lung cancer risk factors. African Americans had interactions of similar magnitude that were not statistically significant. Results for M2 were very similar. Inverse interactions of CYP1A1 variants and smoking-associated lung cancer risk in Latinos might be causal, due to undetected bias or confounding, or represent a unique linkage disequilibrium between a new lung cancer locus and CYP1A1 in this highly admixed population. [source] Cytonuclear disequilibrium in a hybrid zone involving deep-sea hydrothermal vent mussels of the genus BathymodiolusMOLECULAR ECOLOGY, Issue 11 2003Y. Won Abstract A hybrid zone involving the deep-sea mussels, Bathymodiolus azoricus and B. puteoserpentis, was recently discovered at Broken Spur hydrothermal vent field (29°10, N, 43°10, W) along an intermediate segment of the Mid-Atlantic Ridge axis. Examination of nuclear (allozymes) and cytoplasmic (mitochondrial DNA) gene markers in a new sample from Broken Spur revealed significant cytonuclear disequilibrium caused by an excess of the parental types (coupling phase) and a deficiency of recombinants (repulsion phase). An assignment test of individual multilocus genotypes also revealed an excess of parental genotypes in the admixed population. These results support the hypothesis that the Broken Spur mussel population comprises a nonequilibrium mixture of parental immigrants and hybrid individuals. [source] lea (likelihood-based estimation of admixture): a program to estimate simultaneously admixture and time since the admixture eventMOLECULAR ECOLOGY RESOURCES, Issue 4 2001O. Langella Abstract We consider an admixture event, T generations in the past, where two ,parental' populations, P1 and P2, of size N1 and N2, contribute different proportions into the gene pool of an admixed population, H of size Nh. lea (likelihood-based estimator of admixture) is a program which allows the user to obtain the posterior distribution of the parameters of the model. This includes p1, the contribution of P1, and t1, t2 and th, the time since the admixture event (scaled by the population size) for the three populations. lea allows the user to stop and restart the analyses at any time. [source] Assessing interethnic admixture using an X-linked insertion-deletion multiplexAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2009Elzemar Martins Ribeiro-Rodrigues In this study, a PCR multiplex was optimized, allowing the simultaneous analysis of 13 X-chromosome Insertion/deletion polymorphisms (INDELs). Genetic variation observed in Africans, Europeans, and Native Americans reveals high inter-population variability. The estimated proportions of X-chromosomes in an admixed population from the Brazilian Amazon region show a predominant Amerindian contribution (,41%), followed by European (,32%) and African (,27%) contributions. The proportion of Amerindian contribution based on X-linked data is similar to the expected value based on mtDNA and Y-chromosome information. The accuracy for assessing interethnic admixture, and the high differentiation between African, European, and Native American populations, demonstrates the suitability of this INDEL set to measure ancestry proportions in three-hybrid populations, as it is the case of Latin American populations. Am. J. Hum. Biol. 2009. © 2009 Wiley-Liss, Inc. [source] Evaluating bias due to population stratification in case-control association studies of admixed populations,GENETIC EPIDEMIOLOGY, Issue 1 2004Yiting Wang Abstract The potential for bias from population stratification (PS) has raised concerns about case-control studies involving admixed ethnicities. We evaluated the potential bias due to PS in relating a binary outcome with a candidate gene under simulated settings where study populations consist of multiple ethnicities. Disease risks were assigned within the range of prostate cancer rates of African Americans reported in SEER registries assuming k=2, 5, or 10 admixed ethnicities. Genotype frequencies were considered in the range of 5,95%. Under a model assuming no genotype effect on disease (odds ratio (OR)=1), the range of observed OR estimates ignoring ethnicity was 0.64,1.55 for k=2, 0.72,1.33 for k=5, and 0.81,1.22 for k=10. When genotype effect on disease was modeled to be OR=2, the ranges of observed OR estimates were 1.28,3.09, 1.43,2.65, and 1.62,2.42 for k=2, 5, and 10 ethnicities, respectively. Our results indicate that the magnitude of bias is small unless extreme differences exist in genotype frequency. Bias due to PS decreases as the number of admixed ethnicities increases. The biases are bounded by the minimum and maximum of all pairwise baseline disease odds ratios across ethnicities. Therefore, bias due to PS alone may be small when baseline risk differences are small within major categories of admixed ethnicity, such as African Americans. © 2004 Wiley-Liss, Inc. [source] Genetic composition of Brazilian population samples based on a set of twenty-eight ancestry informative SNPsAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 2 2010Tulio C. Lins Ancestry informative SNPs can be useful to estimate individual and population biogeographical ancestry. Brazilian population is characterized by a genetic background of three parental populations (European, African, and Brazilian Native Amerindians) with a wide degree and diverse patterns of admixture. In this work we analyzed the information content of 28 ancestry-informative SNPs into multiplexed panels using three parental population sources (African, Amerindian, and European) to infer the genetic admixture in an urban sample of the five Brazilian geopolitical regions. The SNPs assigned apart the parental populations from each other and thus can be applied for ancestry estimation in a three hybrid admixed population. Data was used to infer genetic ancestry in Brazilians with an admixture model. Pairwise estimates of Fst among the five Brazilian geopolitical regions suggested little genetic differentiation only between the South and the remaining regions. Estimates of ancestry results are consistent with the heterogeneous genetic profile of Brazilian population, with a major contribution of European ancestry (0.771) followed by African (0.143) and Amerindian contributions (0.085). The described multiplexed SNP panels can be useful tool for bioanthropological studies but it can be mainly valuable to control for spurious results in genetic association studies in admixed populations. Am. J. Hum. Biol., 2010. © 2009 Wiley-Liss, Inc. [source] Recent advances of genetic ancestry testing in biomedical research and direct to consumer testingCLINICAL GENETICS, Issue 3 2009M Via In the post-Human Genome Project era, the debate on the concept of race/ethnicity and its implications for biomedical research are dependent on two critical issues: whether and how to classify individuals and whether biological factors play a role in health disparities. The advent of reliable estimates of genetic (or biogeographic) ancestry has provided this debate with a quantitative and more objective tool. The estimation of genetic ancestry allows investigators to control for population stratification in association studies and helps to detect biological causation behind population-specific differences in disease and drug response. New techniques such as admixture mapping can specifically detect population-specific risk alleles for a disease in admixed populations. However, researchers have to be mindful of the correlation between genetic ancestry and socioeconomic and environmental factors that could underlie these differences. More importantly, researchers must avoid the stigmatization of individuals based on perceived or real genetic risks. The latter point will become increasingly sensitive as several ,for profit companies' are offering ancestry and genetic testing directly to consumers and the consequences of the spread of the services of these companies are still unforeseeable. [source] | |||||||||||||