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Population Admixture (population + admixture)
Selected AbstractsMethod for using complete and incomplete trios to identify genes related to a quantitative trait,GENETIC EPIDEMIOLOGY, Issue 1 2004Emily O. Kistner Abstract A number of tests for linkage and association with qualitative traits have been developed, with the most well-known being the transmission/disequilibrium test (TDT). For quantitative traits, varying extensions of the TDT have been suggested. The quantitative trait approach we propose is based on extending the log-linear model for case-parent trio data (Weinberg et al. [1998] Am. J. Hum. Genet. 62:969,978). Like the log-linear approach for qualitative traits, our proposed polytomous logistic approach for quantitative traits allows for population admixture by conditioning on parental genotypes. Compared to other methods, simulations demonstrate good power and robustness of the proposed test under various scenarios of the genotype effect, distribution of the quantitative trait, and population stratification. In addition, missing parental genotype data can be accommodated through an expectation-maximization (EM) algorithm approach. The EM approach allows recovery of most of the lost power due to incomplete trios. Published 2004 Wiley-Liss, Inc. [source] Does the relationship between IgE and the CD14 gene depend on ethnicity?ALLERGY, Issue 11 2008G. Zhang This review considers the data from studies analysing associations between the CD14C,159T single nucleotide polymorphism (SNP) and asthmatic phenotypes and discusses the variability of the conclusions. By searching PubMed and EMBASE for articles on CD14C,159T -related population or family-based association studies, 47 were identified up till September 2007. Collectively, the studies reviewed herein consistently showed population differences in frequencies of the alleles of the SNP, with African descent having the highest C allele frequencies, followed by Caucasians and Asians. The T allele of the SNP was associated with increased sCD14 in some studies but not in others. Inconsistently, the C allele, or even occasionally the T allele, was associated with atopic phenotypes in a population subgroup. There are several explanations for these inconsistencies, including lack of power, linkage disequilibrium, gene,gene interactions, population admixture and gene,environment interactions. If the SNP was associated with functional changes to the coded protein and thus modulating susceptibility to allergic disease, its effect may be modest and dependent on other co-existent, ethnicity-specific, genetic or environmental risk factors. [source] High intercontinental migration rates and population admixture in the sapstain fungus Ophiostoma ipsMOLECULAR ECOLOGY, Issue 1 2007XUDONG ZHOU Abstract Ophiostoma ips is a common fungal associate of various conifer-infesting bark beetles in their native ranges and has been introduced into non-native pine plantations in the Southern Hemisphere. In this study, we used 10 microsatellite markers to investigate the population biology of O. ips in native (Cuba, France, Morocco and USA) and non-native (Australia, Chile and South Africa) areas to characterize host specificity, reproductive behaviour, and the potential origin as well as patterns of spread of the fungus and its insect vectors. The markers resolved a total of 41 alleles and 75 haplotypes. Higher genetic diversity was found in the native populations than in the introduced populations. Based on the origin of the insect vectors, the populations of O. ips in Australia would be expected to reflect a North American origin, and those in Chile and South Africa to reflect a European origin. However, most alleles observed in the native European population were also found in the native North American population; only the allele frequencies among the populations varied. This admixture made it impossible to confirm the origin of the introduced Southern Hemisphere (SH) populations of O. ips. There was also no evidence for specificity of the fungus to particular bark beetle vectors or hosts. Although O. ips is thought to be mainly self-fertilizing, evidence for recombination was found in the four native populations surveyed. The higher genetic diversity in the North American than in the European population suggests that North America could be the possible source region of O. ips. [source] Development of microsatellite loci in pinto abalone (Haliotis kamtschatkana)MOLECULAR ECOLOGY RESOURCES, Issue 4 2001K. M. Miller Abstract Twelve novel di-, tri- and tetranucleotide microsatellite loci to the pinto abalone (Haliotis kamtschatkana) are described. Over 400 individuals were analysed at each microsatellite locus. Observed heterozygosities ranged from 0.44 to 0.93, and numbers of alleles from 20 to 63. Six of the loci contained excesses in homozygosity indicative of inbreeding, nonrandom mating, population admixture, or null alleles. [source] Genetics and Asthma Disease Susceptibility in the US Latino PopulationMOUNT SINAI JOURNAL OF MEDICINE: A JOURNAL OF PERSONALIZED AND TRANSLATIONAL MEDICINE, Issue 2 2010Joan Reibman MD Abstract The US Latino population is heterogeneous with diversity in environmental exposures and socioeconomic status. Moreover, the US Hispanic population derives from numerous countries previously under Spanish rule, and many Hispanics have complex proportions of European, Native American, and African ancestry. Disparities in asthma severity and control are due to complex interactions between environmental exposures, socioeconomic factors, and genetic variations. In addition, diseases within the Latino community may also differ by country of origin. Although US Census data show low asthma rates in the Hispanic population as a whole, there is a lot of variability in the prevalence and morbidity of asthma, with a prevalence of 5.0% in Mexican Americans versus 17.0% in Puerto Ricans. The diversity and population admixture make the study of the genetics of asthma complex in Latino populations. However, an understanding of the genetics of asthma in all populations, including the Latino population, can enhance risk identification, help us to target pharmacological therapy, and guide environmental regulations, all of which can promote a reduction in health disparities. The inclusion of markers of ancestral diversity and the incorporation of techniques to adjust for stratification now make these studies feasible in complex populations, including the Latino population. To date, studies using linkage analyses, genome-wide associations, or candidate gene analyses have identified an association of asthma or asthma-related phenotypes with candidate genes, including interleukin 13, ,-2 adrenergic receptor, a disintegrin and metalloproteinase 33, orosomucoid 1-like 3, and thymic stromal lymphopoietin. As reviewed here, although these genes have been identified in diverse populations, limited studies have been performed in Latino populations, and they have had variable replication. There is a need for the development of registries with well-phenotyped pediatric and adult Latino populations and subgroups for inclusion in the rapidly expanding field of genetic studies, and these studies need to be used to reduce health disparities. Mt Sinai J Med 77:140,148, 2010. © 2010 Mount Sinai School of Medicine [source] mtDNA variability in two Bantu-speaking populations (Shona and Hutu) from Eastern Africa: Implications for peopling and migration patterns in sub-Saharan AfricaAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009Loredana Castŕ Abstract In this study, we report novel data on mitochondrial DNA in two of the largest eastern Bantu-speaking populations, the Shona from Zimbabwe and the Hutu from Rwanda. The goal is to evaluate the genetic relationships of these two ethnic groups with other Bantu-speaking populations. Moreover, by comparing our data with those from other Niger-Congo speaking populations, we aim to clarify some aspects of evolutionary and demographic processes accompanying the spread of Bantu languages in sub-Saharan Africa and to test if patterns of genetic variation fit with models of population expansion based on linguistic and archeological data. The results indicate that the Shona and Hutu are closely related to the other Bantu-speaking populations. However, there are some differences in haplogroup composition between the two populations, mainly due to different genetic contributions from neighboring populations. This result is confirmed by estimates of migration rates which show high levels of gene flow not only between pairs of Bantu-speaking populations, but also between Bantu and non-Bantu speakers. The observed pattern of genetic variability (high genetic homogeneity and high levels of gene flow) supports a linguistic model suggesting a gradual spread of Bantu-speakers, with strong interactions between the different lines of Bantu-speaker descent, and is also in agreement with recent archeological findings. In conclusion, our data emphasize the role that population admixture has played at different times and to varying degrees in the dispersal of Bantu languages. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source] | |||||||||||||