Schurr, Theodore G

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Now showing 1 - 10 of 32
  • Publication
    Y-Chromosome Variation in Altaian Kazakhs Reveals a Common Paternal Gene Pool for Kazakhs and the Influence of Mongolian Expansions
    (2011-03-11) Dulik, Matthew C; Schurr, Theodore G; Osipova, Ludmila P
    Kazakh populations have traditionally lived as nomadic pastoralists that seasonally migrate across the steppe and surrounding mountain ranges in Kazakhstan and southern Siberia. To clarify their population history from a paternal perspective, we analyzed the non-recombining portion of the Y-chromosome from Kazakh populations living in southern Altai Republic, Russia, using a high-resolution analysis of 60 biallelic markers and 17 STRs. We noted distinct differences in the patterns of genetic variation between maternal and paternal genetic systems in the Altaian Kazakhs. While they possess a variety of East and West Eurasian mtDNA haplogroups, only three East Eurasian paternal haplogroups appear at significant frequencies (C3*, C3c and O3a3c*). In addition, the Y-STR data revealed low genetic diversity within these lineages. Analysis of the combined biallelic and STR data also demonstrated genetic differences among Kazakh populations from across Central Asia. The observed differences between Altaian Kazakhs and indigenous Kazakhs were not the result of admixture between Altaian Kazakhs and indigenous Altaians. Overall, the shared paternal ancestry of Kazakhs differentiates them from other Central Asian populations. In addition, all of them showed evidence of genetic influence by the 13th century CE Mongol Empire. Ultimately, the social and cultural traditions of the Kazakhs shaped their current pattern of genetic variation.
  • Publication
    Evaluation of Group Genetic Ancestry of Populations From Philadelphia and Dakar in the Context of Sex-Biased Admixture in the Americas
    (2009-11-25) Dulik, Matthew C; Stefflova, Klara; Pai, Athma A; Walker, Amy H; Schurr, Theodore G; Zeigler-Johnson, Charnita M; Rebbeck, Timothy R; Gueye, Serigne M
    Background Population history can be reflected in group genetic ancestry, where genomic variation captured by the mitochondrial DNA (mtDNA) and non-recombining portion of the Y chromosome (NRY) can separate female- and male-specific admixture processes. Genetic ancestry may influence genetic association studies due to differences in individual admixture within recently admixed populations like African Americans. Principal Findings We evaluated the genetic ancestry of Senegalese as well as European Americans and African Americans from Philadelphia. Senegalese mtDNA consisted of ~12% U haplotypes (U6 and U5b1b haplotypes, common in North Africa) while the NRY haplotypes belonged solely to haplogroup E. In Philadelphia, we observed varying degrees of admixture. While African Americans have 9–10% mtDNAs and ~31% NRYs of European origin, these results are not mirrored in the mtDNA/NRY pools of European Americans: they have less than 7% mtDNAs and less than 2% NRYs from non-European sources. Additionally, there is <2% Native American contribution to Philadelphian African American ancestry and the admixture from combined mtDNA/NRY estimates is consistent with the admixture derived from autosomal genetic data. To further dissect these estimates, we have analyzed our samples in the context of different demographic groups in the Americas. Conclusions We found that sex-biased admixture in African-derived populations is present throughout the Americas, with continual influence of European males, while Native American females contribute mainly to populations of the Caribbean and South America. The high non-European female contribution to the pool of European-derived populations is consistently characteristic of Iberian colonization. These data suggest that genomic data correlate well with historical records of colonization in the Americas.
  • Publication
    Genetic Background and Climatic Droplet Keratopathy Incidence in a Mapuche Population From Argentina
    (2013-09-05) Schurr, Theodore G; Dulik, Matthew C; Cafaro, Thamara A; Suarez, María F; Urrets-Zavalia, Julio A; Serra, Horacio M
    Purpose To determine whether the incidence of and susceptibility to climatic droplet keratopathy (CDK), an acquired, often bilateral degenerative corneal disease, is influenced by the genetic background of the individuals who exhibit the disorder. Methods To determine whether the disease expression was influenced by the genetic ancestry of CDK cases in native Mapuche of the northwest area of Patagonia in Argentina, we examined mitochondrial DNA and Y-chromosome variation in 53 unrelated individuals. Twenty-nine of them were part of the CDK (patient) population, while 24 were part of the control group. The analysis revealed the maternal and paternal lineages that were present in the two study groups. Results This analysis demonstrated that nearly all persons had a Native American mtDNA background, whereas 50% of the CDK group and 37% of the control group had Native American paternal ancestry, respectively. There was no significant difference in the frequencies of mtDNA haplogroups between the CDK patient and control groups. Although the Y-chromosome data revealed differences in specific haplogroup frequencies between these two groups, there was no statistically significant relationship between individual paternal genetic backgrounds and the incidence or stage of disease. Conclusions These results indicate a lack of correlation between genetic ancestry as represented by haploid genetic systems and the incidence of CDK in Mapuche populations. In addition, the mtDNA appears to play less of a role in CDK expression than for other complex diseases linked to bioenergetic processes. However, further analysis of the mtDNA genome sequence and other genes involved in corneal function may reveal the more precise role that mitochondria play in the expression of CDK.
  • Publication
    Russian Old Believers: Genetic Consequences of Their Persecution and Exile, as Shown by Mitochondrial DNA Evidence
    (2008-06-01) Dulik, Matthew C; Rubinstein, Samara; Gokcumen, Omer; Zhadanov, Sergey I; Osipova, Ludmila P; Cocca, Maggie; Mehta, Nishi; Gubina, Marina; Schurr, Theodore G; Posukh, Olga
    In 1653, the Patriarch Nikon modified liturgical practices to bring the Russian Orthodox Church in line with those of the Eastern (Greek) Orthodox Church, from which it had split 200 years earlier. The Old Believers (staroveri) rejected these changes and continued to worship using the earlier practices. These actions resulted in their persecution by the Russian Orthodox Church, which forced them into exile across Siberia. Given their history, we investigate whether populations of Old Believers have diverged genetically from other Slavic populations as a result of their isolation. We also examine whether the three Old Believer populations analyzed in this study are part of a single gene pool (founder population) or are instead derived from heterogeneous sources. As part of this analysis, we survey the mitochondrial DNAs (mtDNAs) of 189 Russian Old Believer individuals from three populations in Siberia and 201 ethnic Russians from different parts of Siberia for phylogenetically informative mutations in the coding and noncoding regions. Our results indicate that the Old Believers have not significantly diverged genetically from other Slavic populations over the 200-300 years of their isolation in Siberia. However, they do show some unique patterns of mtDNA variation relative to other Slavic groups, such as a high frequency of subhaplogroup U4, a surprisingly low frequency of haplogroup H, and low frequencies of the rare East Eurasian subhaplogroup D5.
  • Publication
    Hasanlu IVB: An Ancient DNA Pilot Project
    (2015-01-01) Dulik, Matthew C; Schurr, Theodore G; Lorenz, Joseph G
  • Publication
    A Novel 154-bp Deletion in the Human Mitochondrial DNA Control Region in Healthy Individuals
    (2008-12-01) Behar, Doron M; Blue-Smith, Jason; Soria-Hernanz, David F; Tzur, Shay; Hadid, Yarin; Bormans, Concetta; Moen, Alexander; Tyler-Smith, Chris; Quintana-Murci, Lluis; Wells, R. Spencer; Schurr, Theodore G
    The biological role of the mitochondrial DNA (mtDNA) control region in mtDNA replication remains unclear. In a worldwide survey of mtDNA variation in the general population, we have identified a novel large control region deletion spanning positions 16154 to 16307 (m.16154_16307del154). The population prevalence of this deletion is low, since it was only observed in 1 out of over 120,000 mtDNA genomes studied. The deletion is present in a nonheteroplasmic state, and was transmitted by a mother to her two sons with no apparent past or present disease conditions. The identification of this large deletion in healthy individuals challenges the current view of the control region as playing a crucial role in the regulation of mtDNA replication, and supports the existence of a more complex system of multiple or epigenetically-determined replication origins.
  • Publication
    Neolithic Mitochondrial Haplogroup H Genomes and the Genetic Origins of Europeans
    (2013-04-23) Dulik, Matthew; Gaieski, Jill Bennett; Schurr, Theodore G; Genographic Consortium
    Haplogroup H dominates present-day Western European mitochondrial DNA variability (>40%), yet was less common (~19%) among Early Neolithic farmers (~5450 BC) and virtually absent in Mesolithic hunter-gatherers. Here we investigate this major component of the maternal population history of modern Europeans and sequence 39 complete haplogroup H mitochondrial genomes from ancient human remains. We then compare this â real-timeâ genetic data with cultural changes taking place between the Early Neolithic (~5450 BC) and Bronze Age (~2200 BC) in Central Europe. Our results reveal that the current diversity and distribution of haplogroup H were largely established by the Mid Neolithic (~4000 BC), but with substantial genetic contributions from subsequent pan-European cultures such as the Bell Beakers expanding out of Iberia in the Late Neolithic (~2800 BC). Dated haplogroup H genomes allow us to reconstruct the recent evolutionary history of haplogroup H and reveal a mutation rate 45% higher than current estimates for human mitochondria.
  • Publication
    Mitochondrial Genetic Diversity and its Determinants in Island Melanesia
    (2005-01-01) Friedlaender, Jonathan S; Gentz, Fred; Friedlaender, Françoise R; Kaestle, Frederika; Schurr, Theodore G; Koki, George; Schanfield, Moses; McDonough, John; Smith, Lydia; Cerchio, Sal; Mgone, Charles; Merriwether, D. Andrew
    For a long time, many physical anthropologists and human geneticists considered Island Melanesian populations to be genetically impoverished, dominated by the effects of random genetic drift because of their small sizes, internally very homogeneous, and therefore of little relevance in reconstructing past human migrations. This view is changing. Here we present the developing detailed picture of mitochondrial DNA (mtDNA) variation in eastern New Guinea and Island Melanesia that reflects linguistic distinctions within the region as well as considerable island-by-island isolation. It also appears that the patterns of variation reflect marital migration distinctions between bush and beach populations. We have identified a number of regionally specific mtDNA variants. We also question the widely accepted hypothesis that the mtDNA variant referred to as the ‘Polynesian Motif’ (or alternatively the ‘Austronesian Motif’) developed outside this region somewhere to the west. It may well have first appeared among certain non-Austronesian speaking groups in eastern New Guinea or the Bismarcks. Overall, the developing mtDNA pattern appears to be more easily reconciled with that of other genetic and biometric variables.
  • Publication
    Y-Chromosome Analysis in Individuals Bearing the Basarab Name of the First Dynasty of Wallachian Kings
    (2012-07-25) Genographic Consortium; Schurr, Theodore G
    Vlad III The Impaler, also known as Dracula, descended from the dynasty of Basarab, the first rulers of independent Wallachia, in present Romania. Whether this dynasty is of Cuman (an admixed Turkic people that reached Wallachia from the East in the 11th century) or of local Romanian (Vlach) origin is debated among historians. Earlier studies have demonstrated the value of investigating the Y chromosome of men bearing a historical name, in order to identify their genetic origin. We sampled 29 Romanian men carrying the surname Basarab, in addition to four Romanian populations (from counties Dolj, N = 38; Mehedinti, N = 11; Cluj, N = 50; and Brasov, N = 50), and compared the data with the surrounding populations. We typed 131 SNPs and 19 STRs in the non-recombinant part of the Y-chromosome in all the individuals. We computed a PCA to situate the Basarab individuals in the context of Romania and its neighboring populations. Different Y-chromosome haplogroups were found within the individuals bearing the Basarab name. All haplogroups are common in Romania and other Central and Eastern European populations. In a PCA, the Basarab group clusters within other Romanian populations. We found several clusters of Basarab individuals having a common ancestor within the period of the last 600 years. The diversity of haplogroups found shows that not all individuals carrying the surname Basarab can be direct biological descendants of the Basarab dynasty. The absence of Eastern Asian lineages in the Basarab men can be interpreted as a lack of evidence for a Cuman origin of the Basarab dynasty, although it cannot be positively ruled out. It can be therefore concluded that the Basarab dynasty was successful in spreading its name beyond the spread of its genes.
  • Publication
    Mitochondrial Genome Sequencing in Mesolithic North East Europe Unearths a New Sub-Clade Within the Broadly Distributed Human Haplogroup C1
    (2014-02-04) Genographic Consortium; Schurr, Theodore G
    The human mitochondrial haplogroup C1 has a broad global distribution but is extremely rare in Europe today. Recent ancient DNA evidence has demonstrated its presence in European Mesolithic individuals. Three individuals from the 7,500 year old Mesolithic site of Yuzhnyy Oleni Ostrov, Western Russia, could be assigned to haplogroup C1 based on mitochondrial hypervariable region I sequences. However, hypervariable region I data alone could not provide enough resolution to establish the phylogenetic relationship of these Mesolithic haplotypes with haplogroup C1 mitochondrial DNA sequences found today in populations of Europe, Asia and the Americas. In order to obtain high-resolution data and shed light on the origin of this European Mesolithic C1 haplotype, we target-enriched and sequenced the complete mitochondrial genome of one Yuzhnyy Oleni Ostrov C1 individual. The updated phylogeny of C1 haplogroups indicated that the Yuzhnyy Oleni Ostrov haplotype represents a new distinct clade, provisionally coined â C1fâ . We show that all three C1 carriers of Yuzhnyy Oleni Ostrov belong to this clade. No haplotype closely related to the C1f sequence could be found in the large current database of ancient and present-day mitochondrial genomes. Hence, we have discovered past human mitochondrial diversity that has not been observed in modern-day populations so far. The lack of positive matches in modern populations may be explained by under-sampling of rare modern C1 carriers or by demographic processes, population extinction or replacement, that may have impacted on populations of Northeast Europe since prehistoric times.