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1.
Eur J Hum Genet ; 2020 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-33139852

RESUMO

The influence of Viking-Age migrants to the British Isles is obvious in archaeological and place-names evidence, but their demographic impact has been unclear. Autosomal genetic analyses support Norse Viking contributions to parts of Britain, but show no signal corresponding to the Danelaw, the region under Scandinavian administrative control from the ninth to eleventh centuries. Y-chromosome haplogroup R1a1 has been considered as a possible marker for Viking migrations because of its high frequency in peninsular Scandinavia (Norway and Sweden). Here we select ten Y-SNPs to discriminate informatively among hg R1a1 sub-haplogroups in Europe, analyse these in 619 hg R1a1 Y chromosomes including 163 from the British Isles, and also type 23 short-tandem repeats (Y-STRs) to assess internal diversity. We find three specifically Western-European sub-haplogroups, two of which predominate in Norway and Sweden, and are also found in Britain; star-like features in the STR networks of these lineages indicate histories of expansion. We ask whether geographical distributions of hg R1a1 overall, and of the two sub-lineages in particular, correlate with regions of Scandinavian influence within Britain. Neither shows any frequency difference between regions that have higher (≥10%) or lower autosomal contributions from Norway and Sweden, but both are significantly overrepresented in the region corresponding to the Danelaw. These differences between autosomal and Y-chromosomal histories suggest either male-specific contribution, or the influence of patrilocality. Comparison of modern DNA with recently available ancient DNA data supports the interpretation that two sub-lineages of hg R1a1 spread with the Vikings from peninsular Scandinavia.

2.
Nat Commun ; 11(1): 5182, 2020 10 14.
Artigo em Inglês | MEDLINE | ID: mdl-33057025

RESUMO

Chronic obstructive pulmonary disease (COPD), diagnosed by reduced lung function, is a leading cause of morbidity and mortality. We performed whole genome sequence (WGS) analysis of lung function and COPD in a multi-ethnic sample of 11,497 participants from population- and family-based studies, and 8499 individuals from COPD-enriched studies in the NHLBI Trans-Omics for Precision Medicine (TOPMed) Program. We identify at genome-wide significance 10 known GWAS loci and 22 distinct, previously unreported loci, including two common variant signals from stratified analysis of African Americans. Four novel common variants within the regions of PIAS1, RGN (two variants) and FTO show evidence of replication in the UK Biobank (European ancestry n ~ 320,000), while colocalization analyses leveraging multi-omic data from GTEx and TOPMed identify potential molecular mechanisms underlying four of the 22 novel loci. Our study demonstrates the value of performing WGS analyses and multi-omic follow-up in cohorts of diverse ancestry.


Assuntos
Afro-Americanos/genética , Loci Gênicos , Doença Pulmonar Obstrutiva Crônica/genética , Fenômenos Fisiológicos Respiratórios/genética , Sequenciamento Completo do Genoma , Adulto , Idoso , Idoso de 80 Anos ou mais , Dioxigenase FTO Dependente de alfa-Cetoglutarato/genética , Proteínas de Ligação ao Cálcio/genética , Estudos de Viabilidade , Feminino , Seguimentos , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Pulmão/fisiopatologia , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Proteínas Inibidoras de STAT Ativados/genética , Doença Pulmonar Obstrutiva Crônica/etnologia , Doença Pulmonar Obstrutiva Crônica/fisiopatologia , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/genética
3.
Mol Psychiatry ; 25(10): 2392-2409, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-30617275

RESUMO

Smoking is a major heritable and modifiable risk factor for many diseases, including cancer, common respiratory disorders and cardiovascular diseases. Fourteen genetic loci have previously been associated with smoking behaviour-related traits. We tested up to 235,116 single nucleotide variants (SNVs) on the exome-array for association with smoking initiation, cigarettes per day, pack-years, and smoking cessation in a fixed effects meta-analysis of up to 61 studies (up to 346,813 participants). In a subset of 112,811 participants, a further one million SNVs were also genotyped and tested for association with the four smoking behaviour traits. SNV-trait associations with P < 5 × 10-8 in either analysis were taken forward for replication in up to 275,596 independent participants from UK Biobank. Lastly, a meta-analysis of the discovery and replication studies was performed. Sixteen SNVs were associated with at least one of the smoking behaviour traits (P < 5 × 10-8) in the discovery samples. Ten novel SNVs, including rs12616219 near TMEM182, were followed-up and five of them (rs462779 in REV3L, rs12780116 in CNNM2, rs1190736 in GPR101, rs11539157 in PJA1, and rs12616219 near TMEM182) replicated at a Bonferroni significance threshold (P < 4.5 × 10-3) with consistent direction of effect. A further 35 SNVs were associated with smoking behaviour traits in the discovery plus replication meta-analysis (up to 622,409 participants) including a rare SNV, rs150493199, in CCDC141 and two low-frequency SNVs in CEP350 and HDGFRP2. Functional follow-up implied that decreased expression of REV3L may lower the probability of smoking initiation. The novel loci will facilitate understanding the genetic aetiology of smoking behaviour and may lead to the identification of potential drug targets for smoking prevention and/or cessation.

4.
Arterioscler Thromb Vasc Biol ; 39(11): 2386-2401, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31644355

RESUMO

OBJECTIVE: The male-specific region of the Y chromosome (MSY) remains one of the most unexplored regions of the genome. We sought to examine how the genetic variants of the MSY influence male susceptibility to coronary artery disease (CAD) and atherosclerosis. Approach and Results: Analysis of 129 133 men from UK Biobank revealed that only one of 7 common MSY haplogroups (haplogroup I1) was associated with CAD-carriers of haplogroup I1 had ≈11% increase in risk of CAD when compared with all other haplogroups combined (odds ratio, 1.11; 95% CI, 1.04-1.18; P=6.8×10-4). Targeted MSY sequencing uncovered 235 variants exclusive to this haplogroup. The haplogroup I1-specific variants showed 2.45- and 1.56-fold respective enrichment for promoter and enhancer chromatin states, in cells/tissues relevant to atherosclerosis, when compared with other MSY variants. Gene set enrichment analysis in CAD-relevant tissues showed that haplogroup I1 was associated with changes in pathways responsible for early and late stages of atherosclerosis development including defence against pathogens, immunity, oxidative phosphorylation, mitochondrial respiration, lipids, coagulation, and extracellular matrix remodeling. UTY was the only Y chromosome gene whose blood expression was associated with haplogroup I1. Experimental reduction of UTY expression in macrophages led to changes in expression of 59 pathways (28 of which overlapped with those associated with haplogroup I1) and a significant reduction in the immune costimulatory signal. CONCLUSIONS: Haplogroup I1 is enriched for regulatory chromatin variants in numerous cells of relevance to CAD and increases cardiovascular risk through proatherosclerotic reprogramming of the transcriptome, partly through UTY.


Assuntos
Cromossomos Humanos Y , Doença da Artéria Coronariana/genética , Pleiotropia Genética , Predisposição Genética para Doença , Expressão Gênica , Haplótipos , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Macrófagos/metabolismo , Masculino , Antígenos de Histocompatibilidade Menor/genética , Proteínas Nucleares/genética , Filogenia , Fatores de Risco , Células THP-1
6.
Clin Transl Radiat Oncol ; 18: 1-8, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31341970

RESUMO

Predicting which patients will develop adverse reactions to radiotherapy is important for personalised treatment. Prediction will require an algorithm or nomogram combining clinical and biological data. The radiation-induced lymphocyte apoptosis (RILA) assay is the leading candidate as a biological predictor of radiotherapy toxicity. In this study we tested the potential of the assay for standardisation and use in multiple testing laboratories. The assay was standardised and reproducibility determined using samples from healthy volunteers assayed concurrently in three laboratories in Leicester (UK), Mannheim (Germany) and Montpellier (France). RILA assays were performed on samples taken prior to radiotherapy from 1319 cancer patients enrolled in the REQUITE project at multiple centres. The patients were being treated for breast (n = 753), prostate (n = 506) or lung (n = 60) cancer. Inter-laboratory comparisons identified several factors affecting results: storage time, incubation periods and type of foetal calf serum. Following standardisation, there was no significant difference in results between the centres. Significant differences were seen in RILA scores between cancer types (prostate > breast > lung), by smoking status (non-smokers > smokers) and co-morbidity with rheumatoid arthritis (arthritics > non-arthritics). An analysis of acute radiotherapy toxicity showed as expected that RILA assay does not predict most end-points, but unexpectedly did predict acute breast pain. This result may elucidate the mechanism by which the RILA assay predicts late radiotherapy toxicity. The work shows clinical trials involving multiple laboratory measurement of the RILA assay are feasible and the need to account for tumour type and other variables when applying to predictive models.

9.
Nat Genet ; 51(3): 481-493, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30804560

RESUMO

Reduced lung function predicts mortality and is key to the diagnosis of chronic obstructive pulmonary disease (COPD). In a genome-wide association study in 400,102 individuals of European ancestry, we define 279 lung function signals, 139 of which are new. In combination, these variants strongly predict COPD in independent populations. Furthermore, the combined effect of these variants showed generalizability across smokers and never smokers, and across ancestral groups. We highlight biological pathways, known and potential drug targets for COPD and, in phenome-wide association studies, autoimmune-related and other pleiotropic effects of lung function-associated variants. This new genetic evidence has potential to improve future preventive and therapeutic strategies for COPD.


Assuntos
Predisposição Genética para Doença/genética , Pulmão/fisiopatologia , Doença Pulmonar Obstrutiva Crônica/genética , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Feminino , Estudo de Associação Genômica Ampla/métodos , Humanos , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único/genética , Fatores de Risco , Fumar/genética
10.
Biol Psychiatry ; 85(11): 946-955, 2019 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-30679032

RESUMO

BACKGROUND: Smoking and alcohol use have been associated with common genetic variants in multiple loci. Rare variants within these loci hold promise in the identification of biological mechanisms in substance use. Exome arrays and genotype imputation can now efficiently genotype rare nonsynonymous and loss of function variants. Such variants are expected to have deleterious functional consequences and to contribute to disease risk. METHODS: We analyzed ∼250,000 rare variants from 16 independent studies genotyped with exome arrays and augmented this dataset with imputed data from the UK Biobank. Associations were tested for five phenotypes: cigarettes per day, pack-years, smoking initiation, age of smoking initiation, and alcoholic drinks per week. We conducted stratified heritability analyses, single-variant tests, and gene-based burden tests of nonsynonymous/loss-of-function coding variants. We performed a novel fine-mapping analysis to winnow the number of putative causal variants within associated loci. RESULTS: Meta-analytic sample sizes ranged from 152,348 to 433,216, depending on the phenotype. Rare coding variation explained 1.1% to 2.2% of phenotypic variance, reflecting 11% to 18% of the total single nucleotide polymorphism heritability of these phenotypes. We identified 171 genome-wide associated loci across all phenotypes. Fine mapping identified putative causal variants with double base-pair resolution at 24 of these loci, and between three and 10 variants for 65 loci. Twenty loci contained rare coding variants in the 95% credible intervals. CONCLUSIONS: Rare coding variation significantly contributes to the heritability of smoking and alcohol use. Fine-mapping genome-wide association study loci identifies specific variants contributing to the biological etiology of substance use behavior.


Assuntos
Consumo de Bebidas Alcoólicas/fisiopatologia , Exoma , Variação Genética/fisiologia , Fumar/fisiopatologia , Consumo de Bebidas Alcoólicas/genética , Bases de Dados Genéticas , Predisposição Genética para Doença/genética , Estudo de Associação Genômica Ampla/estatística & dados numéricos , Genótipo , Humanos , Análise de Sequência com Séries de Oligonucleotídeos/estatística & dados numéricos , Fenótipo , Polimorfismo de Nucleotídeo Único/genética , Fumar/genética
11.
Sci Rep ; 7(1): 12086, 2017 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-28935946

RESUMO

Interpretations of genetic data concerning the prehistory of Europe have long been a subject of great debate, but increasing amounts of ancient and modern DNA data are now providing new and more informative evidence. Y-chromosome resequencing studies in Europe have highlighted the prevalence of recent expansions of male lineages, and focused interest on the Bronze Age as a period of cultural and demographic change. These findings contrast with phylogeographic studies based on mitochondrial DNA (mtDNA), which have been interpreted as supporting expansions from glacial refugia. Here we have undertaken a population-based resequencing of complete mitochondrial genomes in Europe and the Middle East, in 340 samples from 17 populations for which Y-chromosome sequence data are also available. Demographic reconstructions show no signal of Bronze Age expansion, but evidence of Paleolithic expansions in all populations except the Saami, and with an absence of detectable geographical pattern. In agreement with previous inference from modern and ancient DNA data, the unbiased comparison between the mtDNA and Y-chromosome population datasets emphasizes the sex-biased nature of recent demographic transitions in Europe.


Assuntos
DNA Antigo/análise , DNA Mitocondrial/genética , Genoma Mitocondrial/genética , Análise de Sequência de DNA/métodos , Cromossomos Humanos Y/genética , DNA Antigo/química , DNA Mitocondrial/química , Europa (Continente) , Feminino , Genética Populacional , Haplótipos , Humanos , Masculino , Oriente Médio , Mitocôndrias/genética , Filogeografia
12.
J Virol ; 91(22)2017 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-28835501

RESUMO

The genomes of human herpesvirus 6A (HHV-6A) and HHV-6B have the capacity to integrate into telomeres, the essential capping structures of chromosomes that play roles in cancer and ageing. About 1% of people worldwide are carriers of chromosomally integrated HHV-6 (ciHHV-6), which is inherited as a genetic trait. Understanding the consequences of integration for the evolution of the viral genome, for the telomere, and for the risk of disease associated with carrier status is hampered by a lack of knowledge about ciHHV-6 genomes. Here, we report an analysis of 28 ciHHV-6 genomes and show that they are significantly divergent from the few modern nonintegrated HHV-6 strains for which complete sequences are currently available. In addition, ciHHV-6B genomes in Europeans are more closely related to each other than to ciHHV-6B genomes from China and Pakistan, suggesting regional variation of the trait. Remarkably, at least one group of European ciHHV-6B carriers has inherited the same ciHHV-6B genome, integrated in the same telomere allele, from a common ancestor estimated to have existed 24,500 ± 10,600 years ago. Despite the antiquity of some, and possibly most, germ line HHV-6 integrations, the majority of ciHHV-6B (95%) and ciHHV-6A (72%) genomes contain a full set of intact viral genes and therefore appear to have the capacity for viral gene expression and full reactivation.IMPORTANCE Inheritance of HHV-6A or HHV-6B integrated into a telomere occurs at a low frequency in most populations studied to date, but its characteristics are poorly understood. However, stratification of ciHHV-6 carriers in modern populations due to common ancestry is an important consideration for genome-wide association studies that aim to identify disease risks for these people. Here, we present full sequence analysis of 28 ciHHV-6 genomes and show that ciHHV-6B in many carriers with European ancestry most likely originated from ancient integration events in a small number of ancestors. We propose that ancient ancestral origins for ciHHV-6A and ciHHV-6B are also likely in other populations. Moreover, despite their antiquity, all of the ciHHV-6 genomes appear to retain the capacity to express viral genes, and most are predicted to be capable of full viral reactivation. These discoveries represent potentially important considerations in immunocompromised patients, in particular in organ transplantation and in stem cell therapy.


Assuntos
Cromossomos Humanos , Genoma Humano , Herpesvirus Humano 6/genética , Característica Quantitativa Herdável , Telômero , Integração Viral/genética , Cromossomos Humanos/genética , Cromossomos Humanos/virologia , Feminino , Estudo de Associação Genômica Ampla , Humanos , Masculino , Telômero/genética , Telômero/virologia
13.
Hum Genet ; 136(5): 547-557, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28349239

RESUMO

Males and females display biological differences that lead to a higher variance of offspring number in males, and this is frequently exacerbated in human societies by mating practices, and possibly by past socio-cultural circumstances. This implies that the genetic record might contain the imprint of past male-mediated expansions, which can be investigated by analysing the male-specific region of the Y chromosome (MSY). Here, we review studies that have used MSY data to infer such expansions. Sets of short-tandem repeats define haplotypes of very low average frequencies, but in a few cases, high-frequency haplotypes are observed, forming the core of descent clusters. Estimates of the ages of such clusters, together with geographical information, have been used to propose powerful historical founders, including Genghis Khan, although without direct supporting evidence. Resequencing of multi-megabase segments of MSY has allowed the construction of detailed phylogenies in which branch lengths are proportional to time, leading to the identification of lineage expansions in the last few millennia as well as the more distant past. Comparisons with maternally-inherited mitochondrial DNA sequence data allow the male specificity of some of these expansions to be demonstrated. These include expansions in Europe in the last ~5000 years that may be associated with a cultural shift during the Bronze Age, as well as expansions elsewhere in the world for which explanations from archaeological evidence are not yet clear.


Assuntos
Cromossomos Humanos Y/genética , Evolução Molecular , Família Multigênica , Demografia , Europa (Continente) , Haplótipos , Humanos , Masculino , Repetições de Microssatélites , Polimorfismo de Nucleotídeo Único , Análise de Sequência de DNA
14.
Eur J Hum Genet ; 25(4): 485-492, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-28120839

RESUMO

Human genetic diversity in Europe has been extensively studied using uniparentally inherited sequences (mitochondrial DNA (mtDNA) and the Y chromosome), which reveal very different patterns indicating sex-specific demographic histories. The X chromosome, haploid in males and inherited twice as often from mothers as from fathers, could provide insights into past female behaviours, but has not been extensively investigated. Here, we use HapMap single-nucleotide polymorphism data to identify genome-wide segments of the X chromosome in which recombination is historically absent and mutations are likely to be the only source of genetic variation, referring to these as phylogeographically informative haplotypes on autosomes and X chromosome (PHAXs). Three such sequences on the X chromosome spanning a total of ~49 kb were resequenced in 240 males from Europe, the Middle East and Africa at an average coverage of 181 ×. These PHAXs were confirmed to be essentially non-recombining across European samples. All three loci show highly homogeneous patterns across Europe and are highly differentiated from the African sample. Star-like structures of European-specific haplotypes in median-joining networks indicate past population expansions. Bayesian skyline plots and time-to-most-recent-common-ancestor estimates suggest expansions pre-dating the Neolithic transition, a finding that is more compatible with data on mtDNA than the Y chromosome, and with the female bias of X-chromosomal inheritance. This study demonstrates the potential of the use of X-chromosomal haplotype blocks, and the utility of the accurate ascertainment of rare variants for inferring human demographic history.


Assuntos
Cromossomos Humanos X/genética , Polimorfismo Genético , População/genética , Europa (Continente) , Feminino , Haplótipos , Recombinação Homóloga , Migração Humana , Humanos , Masculino , Mutação , Linhagem
15.
Genome Res ; 26(4): 427-39, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26883546

RESUMO

The distribution of genetic diversity in great ape species is likely to have been affected by patterns of dispersal and mating. This has previously been investigated by sequencing autosomal and mitochondrial DNA (mtDNA), but large-scale sequence analysis of the male-specific region of the Y Chromosome (MSY) has not yet been undertaken. Here, we use the human MSY reference sequence as a basis for sequence capture and read mapping in 19 great ape males, combining the data with sequences extracted from the published whole genomes of 24 additional males to yield a total sample of 19 chimpanzees, four bonobos, 14 gorillas, and six orangutans, in which interpretable MSY sequence ranges from 2.61 to 3.80 Mb. This analysis reveals thousands of novel MSY variants and defines unbiased phylogenies. We compare these with mtDNA-based trees in the same individuals, estimating time-to-most-recent common ancestor (TMRCA) for key nodes in both cases. The two loci show high topological concordance and are consistent with accepted (sub)species definitions, but time depths differ enormously between loci and (sub)species, likely reflecting different dispersal and mating patterns. Gorillas and chimpanzees/bonobos present generally low and high MSY diversity, respectively, reflecting polygyny versus multimale-multifemale mating. However, particularly marked differences exist among chimpanzee subspecies: The western chimpanzee MSY phylogeny has a TMRCA of only 13.2 (10.8-15.8) thousand years, but that for central chimpanzees exceeds 1 million years. Cross-species comparison within a single MSY phylogeny emphasizes the low human diversity, and reveals species-specific branch length variation that may reflect differences in long-term generation times.


Assuntos
DNA Mitocondrial , Hominidae/classificação , Hominidae/genética , Filogenia , Cromossomo Y , Distribuição Animal , Animais , Feminino , Ordem dos Genes , Genoma , Genômica , Humanos , Masculino , Polimorfismo de Nucleotídeo Único , Análise de Sequência de DNA , Comportamento Sexual Animal
16.
Nat Commun ; 6: 7152, 2015 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-25988751

RESUMO

The proportion of Europeans descending from Neolithic farmers ∼ 10 thousand years ago (KYA) or Palaeolithic hunter-gatherers has been much debated. The male-specific region of the Y chromosome (MSY) has been widely applied to this question, but unbiased estimates of diversity and time depth have been lacking. Here we show that European patrilineages underwent a recent continent-wide expansion. Resequencing of 3.7 Mb of MSY DNA in 334 males, comprising 17 European and Middle Eastern populations, defines a phylogeny containing 5,996 single-nucleotide polymorphisms. Dating indicates that three major lineages (I1, R1a and R1b), accounting for 64% of our sample, have very recent coalescent times, ranging between 3.5 and 7.3 KYA. A continuous swathe of 13/17 populations share similar histories featuring a demographic expansion starting ∼ 2.1-4.2 KYA. Our results are compatible with ancient MSY DNA data, and contrast with data on mitochondrial DNA, indicating a widespread male-specific phenomenon that focuses interest on the social structure of Bronze Age Europe.


Assuntos
Análise de Sequência de DNA , Teorema de Bayes , Evolução Biológica , Simulação por Computador , DNA Mitocondrial/genética , Demografia , Emigração e Imigração , Grupos Étnicos/genética , Europa (Continente) , Grupo com Ancestrais do Continente Europeu/genética , Variação Genética , Genética Populacional , Genômica , Geografia , Haplótipos , História Antiga , Humanos , Masculino , Oriente Médio , Mutação , Filogenia , Dinâmica Populacional
17.
Mol Biol Evol ; 32(1): 29-43, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25223418

RESUMO

A consensus on Bantu-speaking populations being genetically similar has emerged in the last few years, but the demographic scenarios associated with their dispersal are still a matter of debate. The frontier model proposed by archeologists postulates different degrees of interaction among incoming agropastoralist and resident foraging groups in the presence of "static" and "moving" frontiers. By combining mitochondrial DNA and Y chromosome data collected from several southern African populations, we show that Bantu-speaking populations from regions characterized by a moving frontier developing after a long-term static frontier have larger hunter-gatherer contributions than groups from areas where a static frontier was not followed by further spatial expansion. Differences in the female and male components suggest that the process of assimilation of the long-term resident groups into agropastoralist societies was gender biased. Our results show that the diffusion of Bantu languages and culture in Southern Africa was a process more complex than previously described and suggest that the admixture dynamics between farmers and foragers played an important role in shaping the current patterns of genetic diversity.


Assuntos
Grupo com Ancestrais do Continente Africano/etnologia , Grupo com Ancestrais do Continente Africano/genética , Cromossomos Humanos Y/genética , DNA Mitocondrial/genética , África Austral/etnologia , Emigração e Imigração , Feminino , Variação Genética , Genética Populacional , Humanos , Masculino , Análise de Componente Principal , Análise de Regressão
18.
Mol Biol Evol ; 32(3): 661-73, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25468874

RESUMO

Many studies of human populations have used the male-specific region of the Y chromosome (MSY) as a marker, but MSY sequence variants have traditionally been subject to ascertainment bias. Also, dating of haplogroups has relied on Y-specific short tandem repeats (STRs), involving problems of mutation rate choice, and possible long-term mutation saturation. Next-generation sequencing can ascertain single nucleotide polymorphisms (SNPs) in an unbiased way, leading to phylogenies in which branch-lengths are proportional to time, and allowing the times-to-most-recent-common-ancestor (TMRCAs) of nodes to be estimated directly. Here we describe the sequencing of 3.7 Mb of MSY in each of 448 human males at a mean coverage of 51×, yielding 13,261 high-confidence SNPs, 65.9% of which are previously unreported. The resulting phylogeny covers the majority of the known clades, provides date estimates of nodes, and constitutes a robust evolutionary framework for analyzing the history of other classes of mutation. Different clades within the tree show subtle but significant differences in branch lengths to the root. We also apply a set of 23 Y-STRs to the same samples, allowing SNP- and STR-based diversity and TMRCA estimates to be systematically compared. Ongoing purifying selection is suggested by our analysis of the phylogenetic distribution of nonsynonymous variants in 15 MSY single-copy genes.


Assuntos
Cromossomos Humanos Y/genética , Polimorfismo de Nucleotídeo Único/genética , Evolução Molecular , Projeto HapMap , Humanos , Masculino , Filogenia , Análise de Sequência de DNA
19.
BMC Evol Biol ; 13: 24, 2013 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-23360301

RESUMO

BACKGROUND: When studying the genetic structure of human populations, the role of cultural factors may be difficult to ascertain due to a lack of formal models. Linguistic diversity is a typical example of such a situation. Patrilocality, on the other hand, can be integrated into a biological framework, allowing the formulation of explicit working hypotheses. The present study is based on the assumption that patrilocal traditions make the hypervariable region I of the mtDNA a valuable tool for the exploration of migratory dynamics, offering the opportunity to explore the relationships between genetic and linguistic diversity. We studied 85 Niger-Congo-speaking patrilocal populations that cover regions from Senegal to Central African Republic. A total of 4175 individuals were included in the study. RESULTS: By combining a multivariate analysis aimed at investigating the population genetic structure, with a Bayesian approach used to test models and extent of migration, we were able to detect a stepping-stone migration model as the best descriptor of gene flow across the region, with the main discontinuities corresponding to forested areas. CONCLUSIONS: Our analyses highlight an aspect of the influence of habitat variation on human genetic diversity that has yet to be understood. Rather than depending simply on geographic linear distances, patterns of female genetic variation vary substantially between savannah and rainforest environments. Our findings may be explained by the effects of recent gene flow constrained by environmental factors, which superimposes on a background shaped by pre-agricultural peopling.


Assuntos
DNA Mitocondrial/genética , Variação Genética , Genética Populacional , Migração Humana , África Central , África Ocidental , Teorema de Bayes , Feminino , Humanos , Linguística , Masculino , Dados de Sequência Molecular , Análise Multivariada
20.
Hum Biol ; 85(4): 597-606, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25019191

RESUMO

In a previous study, we proposed a model for genetic admixture between African hunter-gatherers and food producers, in which we integrated demographic and genetic aspects together with ethnographic knowledge (Destro-Bisol et al. 2004b). In that study it was possible to test the model only using genetic information from widely dispersed and genetically heterogeneous populations. Here we reevaluate the congruence between the model and patterns of genetic variation using an anthropologically and geographically more homogeneous data set that includes Pygmies and farmers from Cameroon, Congo, and the Central African Republic. As implied by the model, the ratios of mtDNA to Y chromosome Nm estimates (effective population size, N, times the migration rate, m; 0.154 in Pygmies and 6.759 in farmers), support an asymmetric gene flow, with a higher Bantu-to-Pygmy gene flow for paternal than for maternal lineages, and vice versa for farmers. Analyses of intra- and interpopulation genetic variation further support the above observation, showing a prevailing effect of genetic drift on maternal lineages and gene flow on paternal lineages among Pygmies, and an opposite pattern among farmers. We also detected differences between patterns for classical and molecular measures of Y chromosome intrapopulation variation, which likely represent signatures of the introgression of Bantu lineages into the gene pool of Pygmy populations. On the whole, our results seem to reflect differences in the demographic history and the degree of patrilocality and polygyny between the two population groups, thus providing further support to our microevolutionary model in an anthropologically coherent framework.


Assuntos
Grupo com Ancestrais do Continente Africano/genética , Cromossomos Humanos Y , DNA Mitocondrial/genética , Fluxo Gênico , Modelos Genéticos , África ao Sul do Saara , Agricultura , Feminino , Genética Populacional , Humanos , Masculino
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