PMC:3492649 / 18693-22900 JSONTXT

{"target":"https://pubannotation.org/docs/sourcedb/PMC/sourceid/3492649","sourcedb":"PMC","sourceid":"3492649","source_url":"https://www.ncbi.nlm.nih.gov/pmc/3492649","text":"Population Admixture in Central Asia\nMany human populations that settled in Central Asia demonstrate an array of mixed anthropological features of East Eurasians (EEA) and West Eurasians (WEA), indicating a possible scenario of biological admixture between already differentiated EEA and WEA populations. However, their complex biological origin and genomic make-up, as well as their genetic interaction with surrounding populations, are not well understood. Despite Central Asia being a vast territory that has been crucial in human history due to its strategic location [69], populations in this region are not on the list of the 2 large-scale international collaborative efforts, such as the International HapMap Project [70] and the 1000 Genome Project [71], and population genomic studies on Central Asian populations have been largely underrepresented in similar efforts worldwide [68, 72-76].\nIn an attempt to decipher the genetic structure and population history in Central Asia, we conducted, to our knowledge, the first genomewide studies of the Uyghur residing in Xinjiang, which is geographically located in Central Asia. Uyghur that settled in Xinjiang of China (UIG) is a population presenting a typical admixture of eastern and western anthropometric traits; we dissected its genomic structure at the population level, individual level, and chromosome level using 20,177 SNPs spanning over almost the entire chromosome 21. Our results showed that UIG was formed by two-way admixture, with 60% of ancestry from EUR and 40% of ancestry from EAS. Overall LD in UIG was similar to that in its parental populations, represented by EAS and EUR for common alleles, and UIG manifested elevation of LD only within 500 kb and at a level of 0.1 \u003c r2 \u003c 0.8 when AIMs were used. The size of chromosomal segments that were derived from EASs and EURs was on average 2.4 cM and 4.1 cM, respectively. Both the magnitude of LD and fragmentary ancestral chromosome segments indicated a long period of history of Uyghur. Under the assumption of a hybrid isolation (HI) model, the admixture event of UIG was estimated to have taken place about 126 (107-146) generations, or 2,520 (2,140-2,920) years ago, assuming 20 years per generation. In spite of the long history and short LD of Uyghur compared with recent admixture populations, such as African-Americans, we suggested that MALD is still applicable in Uyghur, except that about 10-fold AIMs are necessary for a whole-genome scan.\nLater in the same year, following up on our previous study, we conducted a genomewide analysis of admixture for 2 Uyghur population samples (HGDP-UG and PanAsia-UG) collected from northern and southern Xinjiang of China, respectively. Both HGDP-UG and PanAsia-UG showed substantial admixture of EAS and EUR ancestries, with an empirical estimation of ancestry contribution of 53:47 (EAS:EUR) and 48:52 for HGDP-UG and PanAsia-UG, respectively. The effective admixture time under a model with a single pulse of admixture was estimated to be 110 generations and 129 generations; i.e., admixture events occurred about 2,200 years and 2,580 years ago for HGDP-UG and PanAsia-UG, respectively, assuming an average of 20 years per generation. Despite their earlier history versus other admixture populations, such as AfAs and Latinos, admixture mapping, an economical and powerful approach for localizing disease genes, holds equal promise for Uyghurs because of their mixture of ancestry from different continents as well as their large population size. We screened multiple databases and identified a genomewide SNP panel that can distinguish EAS and EUR ancestry of chromosomal segments in Uyghurs. The panel contains 8,150 AIMs showing large frequency differences between EAS and EUR (FST \u003e 0.25, mean FST = 0.43) but little frequency difference (7,999 AIMs validated) within both EAS and EUR populations (FST \u003c 0.05, mean FST \u003c 0.01). We evaluated the effectiveness of this admixture map for localizing disease genes in 2 Uyghur populations. Our map constitutes the first practical resource for admixture mapping in Uyghurs, and it will enable studies of diseases showing different genetic risks in European and EAS populations.","divisions":[{"label":"Title","span":{"begin":0,"end":36}}],"tracks":[{"project":"2_test","denotations":[{"id":"23166524-14872198-44844065","span":{"begin":573,"end":575},"obj":"14872198"},{"id":"23166524-16255080-44844066","span":{"begin":725,"end":727},"obj":"16255080"},{"id":"23166524-20981092-44844067","span":{"begin":758,"end":760},"obj":"20981092"},{"id":"23166524-20007900-44844068","span":{"begin":888,"end":890},"obj":"20007900"},{"id":"23166524-18817904-44844069","span":{"begin":892,"end":894},"obj":"18817904"},{"id":"23166524-19944401-44844069","span":{"begin":892,"end":894},"obj":"19944401"},{"id":"23166524-19407144-44844069","span":{"begin":892,"end":894},"obj":"19407144"},{"id":"23166524-19944404-44844069","span":{"begin":892,"end":894},"obj":"19944404"},{"id":"23166524-20691402-44844069","span":{"begin":892,"end":894},"obj":"20691402"}],"attributes":[{"subj":"23166524-14872198-44844065","pred":"source","obj":"2_test"},{"subj":"23166524-16255080-44844066","pred":"source","obj":"2_test"},{"subj":"23166524-20981092-44844067","pred":"source","obj":"2_test"},{"subj":"23166524-20007900-44844068","pred":"source","obj":"2_test"},{"subj":"23166524-18817904-44844069","pred":"source","obj":"2_test"},{"subj":"23166524-19944401-44844069","pred":"source","obj":"2_test"},{"subj":"23166524-19407144-44844069","pred":"source","obj":"2_test"},{"subj":"23166524-19944404-44844069","pred":"source","obj":"2_test"},{"subj":"23166524-20691402-44844069","pred":"source","obj":"2_test"}]}],"config":{"attribute types":[{"pred":"source","value type":"selection","values":[{"id":"2_test","color":"#ec93dd","default":true}]}]}}