RESUMEN
Geographic patterns in human genetic diversity carry footprints of population history and provide insights for genetic medicine and its application across human populations. Summarizing and visually representing these patterns of diversity has been a persistent goal for human geneticists, and has revealed that genetic differentiation is frequently correlated with geographic distance. However, most analytical methods to represent population structure do not incorporate geography directly, and it must be considered post hoc alongside a visual summary of the genetic structure. Here, we estimate "effective migration" surfaces to visualize how human genetic diversity is geographically structured. The results reveal local patterns of differentiation in detail and emphasize that while genetic similarity generally decays with geographic distance, the relationship is often subtly distorted. Overall, the visualizations provide a new perspective on genetics and geography in humans and insight to the geographic distribution of human genetic variation.
Asunto(s)
Variación Genética , Genética Humana/métodos , Migración Humana , Geografía , HumanosRESUMEN
In many species a fundamental feature of genetic diversity is that genetic similarity decays with geographic distance; however, this relationship is often complex, and may vary across space and time. Methods to uncover and visualize such relationships have widespread use for analyses in molecular ecology, conservation genetics, evolutionary genetics, and human genetics. While several frameworks exist, a promising approach is to infer maps of how migration rates vary across geographic space. Such maps could, in principle, be estimated across time to reveal the full complexity of population histories. Here, we take a step in this direction: we present a method to infer maps of population sizes and migration rates associated with different time periods from a matrix of genetic similarity between every pair of individuals. Specifically, genetic similarity is measured by counting the number of long segments of haplotype sharing (also known as identity-by-descent tracts). By varying the length of these segments we obtain parameter estimates associated with different time periods. Using simulations, we show that the method can reveal time-varying migration rates and population sizes, including changes that are not detectable when using a similar method that ignores haplotypic structure. We apply the method to a dataset of contemporary European individuals (POPRES), and provide an integrated analysis of recent population structure and growth over the last â¼3,000 years in Europe.
Asunto(s)
Evolución Biológica , Variación Genética/genética , Genética de Población , Dinámica Poblacional/estadística & datos numéricos , Europa (Continente) , Haplotipos/genética , Humanos , Densidad de PoblaciónRESUMEN
The UK Biobank project is a prospective cohort study with deep genetic and phenotypic data collected on approximately 500,000 individuals from across the United Kingdom, aged between 40 and 69 at recruitment. The open resource is unique in its size and scope. A rich variety of phenotypic and health-related information is available on each participant, including biological measurements, lifestyle indicators, biomarkers in blood and urine, and imaging of the body and brain. Follow-up information is provided by linking health and medical records. Genome-wide genotype data have been collected on all participants, providing many opportunities for the discovery of new genetic associations and the genetic bases of complex traits. Here we describe the centralized analysis of the genetic data, including genotype quality, properties of population structure and relatedness of the genetic data, and efficient phasing and genotype imputation that increases the number of testable variants to around 96 million. Classical allelic variation at 11 human leukocyte antigen genes was imputed, resulting in the recovery of signals with known associations between human leukocyte antigen alleles and many diseases.
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Bases de Datos Factuales , Genómica , Fenotipo , Adulto , Anciano , Alelos , Biomarcadores/sangre , Biomarcadores/orina , Estatura/genética , Encéfalo/diagnóstico por imagen , Estudios de Cohortes , Bases de Datos Genéticas , Registros Electrónicos de Salud , Familia , Femenino , Estudio de Asociación del Genoma Completo , Haplotipos/genética , Humanos , Estilo de Vida , Complejo Mayor de Histocompatibilidad/genética , Masculino , Persona de Mediana Edad , Control de Calidad , Grupos Raciales/genética , Reino UnidoRESUMEN
We report a novel approach to the classical natural product quinine that is based on two stereoselective key steps, namely a C-H activation and an aldol reaction, to unite the two heterocyclic moieties of the target molecule. This straightforward and flexible strategy enables a concise synthesis of natural (-)-quinine, the first synthesis of unnatural (+)-quinine, and also provides access to unprecedented C3-aryl analogues, which were prepared in only six steps. We additionally demonstrate that these structural analogues exhibit improved antimalarial activity compared with (-)-quinine both inâ vitro and in mice infected with Plasmodium berghei.
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Antimaláricos/síntesis química , Quinina/análogos & derivados , Aldehídos/química , Animales , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Carbono/química , Catálisis , Cristalografía por Rayos X , Hidrógeno/química , Malaria/tratamiento farmacológico , Malaria/veterinaria , Ratones , Conformación Molecular , Plasmodium berghei/efectos de los fármacos , Quinina/farmacología , Quinina/uso terapéutico , Rutenio/química , EstereoisomerismoRESUMEN
Genetic data often exhibit patterns broadly consistent with 'isolation by distance'-a phenomenon where genetic similarity decays with geographic distance. In a heterogeneous habitat, this may occur more quickly in some regions than in others: for example, barriers to gene flow can accelerate differentiation between neighboring groups. We use the concept of 'effective migration' to model the relationship between genetics and geography. In this paradigm, effective migration is low in regions where genetic similarity decays quickly. We present a method to visualize variation in effective migration across a habitat from geographically indexed genetic data. Our approach uses a population genetic model to relate effective migration rates to expected genetic dissimilarities. We illustrate its potential and limitations using simulations and data from elephant, human and Arabidopsis thaliana populations. The resulting visualizations highlight important spatial features of population structure that are difficult to discern using existing methods for summarizing genetic variation.
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Arabidopsis/genética , Elefantes/genética , Genética de Población/métodos , Modelos Genéticos , Programas Informáticos , Migración Animal , Animales , Flujo Génico , Humanos , Repeticiones de Microsatélite , Método de Montecarlo , MigrantesRESUMEN
BACKGROUND: Understanding the genetic basis of airflow obstruction and smoking behaviour is key to determining the pathophysiology of chronic obstructive pulmonary disease (COPD). We used UK Biobank data to study the genetic causes of smoking behaviour and lung health. METHODS: We sampled individuals of European ancestry from UK Biobank, from the middle and extremes of the forced expiratory volume in 1 s (FEV1) distribution among heavy smokers (mean 35 pack-years) and never smokers. We developed a custom array for UK Biobank to provide optimum genome-wide coverage of common and low-frequency variants, dense coverage of genomic regions already implicated in lung health and disease, and to assay rare coding variants relevant to the UK population. We investigated whether there were shared genetic causes between different phenotypes defined by extremes of FEV1. We also looked for novel variants associated with extremes of FEV1 and smoking behaviour and assessed regions of the genome that had already shown evidence for a role in lung health and disease. We set genome-wide significance at p<5â×â10(-8). FINDINGS: UK Biobank participants were recruited from March 15, 2006, to July 7, 2010. Sample selection for the UK BiLEVE study started on Nov 22, 2012, and was completed on Dec 20, 2012. We selected 50,008 unique samples: 10,002 individuals with low FEV1, 10,000 with average FEV1, and 5002 with high FEV1 from each of the heavy smoker and never smoker groups. We noted a substantial sharing of genetic causes of low FEV1 between heavy smokers and never smokers (p=2.29â×â10(-16)) and between individuals with and without doctor-diagnosed asthma (p=6.06â×â10(-11)). We discovered six novel genome-wide significant signals of association with extremes of FEV1, including signals at four novel loci (KANSL1, TSEN54, TET2, and RBM19/TBX5) and independent signals at two previously reported loci (NPNT and HLA-DQB1/HLA-DQA2). These variants also showed association with COPD, including in individuals with no history of smoking. The number of copies of a 150 kb region containing the 5' end of KANSL1, a gene that is important for epigenetic gene regulation, was associated with extremes of FEV1. We also discovered five new genome-wide significant signals for smoking behaviour, including a variant in NCAM1 (chromosome 11) and a variant on chromosome 2 (between TEX41 and PABPC1P2) that has a trans effect on expression of NCAM1 in brain tissue. INTERPRETATION: By sampling from the extremes of the lung function distribution in UK Biobank, we identified novel genetic causes of lung function and smoking behaviour. These results provide new insight into the specific mechanisms underlying airflow obstruction, COPD, and tobacco addiction, and show substantial shared genetic architecture underlying airflow obstruction across individuals, irrespective of smoking behaviour and other airway disease. FUNDING: Medical Research Council.
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Pulmón/fisiopatología , Enfermedad Pulmonar Obstructiva Crónica/genética , Fumar/genética , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Bancos de Muestras Biológicas , Estudios de Casos y Controles , Femenino , Volumen Espiratorio Forzado/genética , Estudios de Asociación Genética , Humanos , Masculino , Persona de Mediana Edad , Polimorfismo de Nucleótido Simple , Factores de Riesgo , Reino Unido , Adulto JovenRESUMEN
Hydrazines form a new family of low molecular-weight reducing agents for diazonium salts. Using only small amounts of hydrazine catalyst, the coupling of diazonium salts to a variety of reactive partners has been achieved, without the requirement for either metal adjuvants or irradiation with visible or ultraviolet light. The generality of the concept proposed herein as well as its advantages in the preparative scale is outlined and discussed.