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78 result(s) for "Blanché, Hélène"
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Adaptive archaic introgression of copy number variants and the discovery of previously unknown human genes
As they migrated out of Africa and into Europe and Asia, anatomically modern humans interbred with archaic hominins, such as Neanderthals and Denisovans. The result of this genetic introgression on the recipient populations has been of considerable interest, especially in cases of selection for specific archaic genetic variants. Hsieh et al. characterized adaptive structural variants and copy number variants that are likely targets of positive selection in Melanesians. Focusing on population-specific regions of the genome that carry duplicated genes and show an excess of amino acid replacements provides evidence for one of the mechanisms by which genetic novelty can arise and result in differentiation between human genomes. Science , this issue p. eaax2083 Melanesians carry adaptive DNA variants derived from archaic hominins. Copy number variants (CNVs) are subject to stronger selective pressure than single-nucleotide variants, but their roles in archaic introgression and adaptation have not been systematically investigated. We show that stratified CNVs are significantly associated with signatures of positive selection in Melanesians and provide evidence for adaptive introgression of large CNVs at chromosomes 16p11.2 and 8p21.3 from Denisovans and Neanderthals, respectively. Using long-read sequence data, we reconstruct the structure and complex evolutionary history of these polymorphisms and show that both encode positively selected genes absent from most human populations. Our results collectively suggest that large CNVs originating in archaic hominins and introgressed into modern humans have played an important role in local population adaptation and represent an insufficiently studied source of large-scale genetic variation.
Genome-wide association study identifies variants at CLU and CR1 associated with Alzheimer's disease
Philippe Amouyel and colleagues report a genome-wide association study for Alzheimer's disease. They identify variants within CLU and CR1 associated with susceptibility to late-onset Alzheimer's disease. The gene encoding apolipoprotein E ( APOE ) on chromosome 19 is the only confirmed susceptibility locus for late-onset Alzheimer's disease. To identify other risk loci, we conducted a large genome-wide association study of 2,032 individuals from France with Alzheimer's disease (cases) and 5,328 controls. Markers outside APOE with suggestive evidence of association ( P < 10 −5 ) were examined in collections from Belgium, Finland, Italy and Spain totaling 3,978 Alzheimer's disease cases and 3,297 controls. Two loci gave replicated evidence of association: one within CLU (also called APOJ ), encoding clusterin or apolipoprotein J, on chromosome 8 (rs11136000, OR = 0.86, 95% CI 0.81–0.90, P = 7.5 × 10 −9 for combined data) and the other within CR1 , encoding the complement component (3b/4b) receptor 1, on chromosome 1 (rs6656401, OR = 1.21, 95% CI 1.14–1.29, P = 3.7 × 10 −9 for combined data). Previous biological studies support roles of CLU and CR1 in the clearance of β amyloid (Aβ) peptide, the principal constituent of amyloid plaques, which are one of the major brain lesions of individuals with Alzheimer's disease.
Haplotype-Based Identification of a Microsomal Transfer Protein Marker Associated with the Human Lifespan
We previously reported a genomewide linkage study for human longevity using 308 long-lived individuals (LLI) (centenarians or near-centenarians) in 137 sibships and identified statistically significant linkage within chromosome 4 near microsatellite D4S1564. This interval spans 12 million bp and contains ≈50 putative genes. To identify the specific gene and gene variants impacting lifespan, we performed a haplotype-based fine-mapping study of the interval. The resulting genetic association study identified a haplotype marker within microsomal transfer protein as a modifier of human lifespan. This same variant was tested in a second cohort of LLI from France, and although the association was not replicated, there was evidence for statistical distortion in the form of Hardy-Weinberg disequilibrium. Microsomal transfer protein has been identified as the rate-limiting step in lipoprotein synthesis and may affect longevity by subtly modulating this pathway. This study provides proof of concept for the feasibility of using the genomes of LLI to identify genes impacting longevity.
The complete genome sequence of a Neanderthal from the Altai Mountains
We present a high-quality genome sequence of a Neanderthal woman from Siberia. We show that her parents were related at the level of half-siblings and that mating among close relatives was common among her recent ancestors. We also sequenced the genome of a Neanderthal from the Caucasus to low coverage. An analysis of the relationships and population history of available archaic genomes and 25 present-day human genomes shows that several gene flow events occurred among Neanderthals, Denisovans and early modern humans, possibly including gene flow into Denisovans from an unknown archaic group. Thus, interbreeding, albeit of low magnitude, occurred among many hominin groups in the Late Pleistocene. In addition, the high-quality Neanderthal genome allows us to establish a definitive list of substitutions that became fixed in modern humans after their separation from the ancestors of Neanderthals and Denisovans. A complete genome sequence is presented of a female Neanderthal from Siberia, providing information about interbreeding between close relatives and uncovering gene flow events among Neanderthals, Denisovans and early modern humans, as well as establishing substitutions that became fixed in modern humans after their separation from the ancestors of Neanderthals and Denisovans. Genome sequence of Neanderthal woman Recent excavations in the Denisova Cave in the Altai Mountains of southern Siberia have yielded a wealth of hominin fossils from a site that has been occupied for perhaps 250,000 years or more. Now a high-quality genome sequence has been determined from a circa 50,000-year-old toe bone — a proximal toe phalanx — excavated from the east gallery of Denisova Cave in 2010. The sequence is that of a Neanderthal woman whose parents were closely related — perhaps half-siblings or uncle and niece. Such inbreeding was also common among her recent ancestors. Comparisons with other archaic and present-day human genomes reveal several gene-flow events among Neanderthals, the closely related Denisovans and early modern humans, possibly including gene flow into Denisovans from an unknown archaic group. The high-quality Neanderthal genome also helps to establish a definitive list of substitutions that became fixed in modern humans after their separation from the ancestors of Neanderthals and Denisovans.
Building the sequence map of the human pan-genome
Here we integrate the de novo assembly of an Asian and an African genome with the NCBI reference human genome, as a step toward constructing the human pan-genome. We identified ∼5 Mb of novel sequences not present in the reference genome in each of these assemblies. Most novel sequences are individual or population specific, as revealed by their comparison to all available human DNA sequence and by PCR validation using the human genome diversity cell line panel. We found novel sequences present in patterns consistent with known human migration paths. Cross-species conservation analysis of predicted genes indicated that the novel sequences contain potentially functional coding regions. We estimate that a complete human pan-genome would contain ∼19–40 Mb of novel sequence not present in the extant reference genome. The extensive amount of novel sequence contributing to the genetic variation of the pan-genome indicates the importance of using complete genome sequencing and de novo assembly.
Association of FOXO3A variation with human longevity confirmed in German centenarians
The human forkhead box O3A gene (FOXO3A) encodes an evolutionarily conserved key regulator of the insulin-IGF1 signaling pathway that is known to influence metabolism and lifespan in model organisms. A recent study described 3 SNPs in the FOXO3A gene that were statistically significantly associated with longevity in a discovery sample of long-lived men of Japanese ancestry [Willcox et al. (2008) Proc Natl Acad Sci USA 105:13987-13992]. However, this finding required replication in an independent population. Here, we have investigated 16 known FOXO3A SNPs in an extensive collection of 1,762 German centenarians/nonagenarians and younger controls and provide evidence that polymorphisms in this gene were indeed associated with the ability to attain exceptional old age. The FOXO3A association was considerably stronger in centenarians than in nonagenarians, highlighting the importance of centenarians for genetic longevity research. Our study extended the initial finding observed in Japanese men to women and indicates that both genders were likely to be equally affected by variation in FOXO3A. Replication in a French centenarian sample generated a trend that supported the previous results. Our findings confirmed the initial discovery in the Japanese sample and indicate FOXO3A as a susceptibility gene for prolonged survival in humans.
Seroprevalence of SARS-CoV-2 IgG Antibodies and Factors Associated with SARS-CoV-2 IgG Neutralizing Activity among Primary Health Care Workers 6 Months after Vaccination Rollout in France
We aimed to investigate the immunoglobulin G response and neutralizing activity against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) among primary health care workers (PHCW) in France and assess the association between the neutralizing activity and several factors, including the coronavirus disease 2019 (COVID-19) vaccination scheme. A cross-sectional survey was conducted between 10 May 2021 and 31 August 2021. Participants underwent capillary blood sampling and completed a questionnaire. Sera were tested for the presence of antibodies against the nucleocapsid (N) protein and the S-1 portion of the spike (S) protein and neutralizing antibodies. In total, 1612 PHCW were included. The overall seroprevalences were: 23.6% (95% confidence interval (CI) 21.6–25.7%) for antibodies against the N protein, 94.7% (93.6–95.7%) for antibodies against the S protein, and 81.3% (79.4–83.2%) for neutralizing antibodies. Multivariate regression analyses showed that detection of neutralizing antibodies was significantly more likely in PHCW with previous SARS-CoV-2 infection than in those with no such history among the unvaccinated (odds ratio (OR) 16.57, 95% CI 5.96–59.36) and those vaccinated with one vaccine dose (OR 41.66, 95% CI 16.05–120.78). Among PHCW vaccinated with two vaccine doses, the detection of neutralizing antibodies was not significantly associated with previous SARS-CoV-2 infection (OR 1.31, 95% CI 0.86–2.07), but was more likely in those that received their second vaccine dose within the three months before study entry than in those vaccinated more than three months earlier (OR 5.28, 95% CI 3.51–8.23). This study highlights that previous SARS-CoV-2 infection and the time since vaccination should be considered when planning booster doses and the design of COVID-19 vaccine strategies.
Nationwide Seroprevalence of SARS-CoV-2 IgG Antibodies among Four Groups of Primary Health-Care Workers and Their Household Contacts 6 Months after the Initiation of the COVID-19 Vaccination Campaign in France: SeroPRIM Study Protocol
Background: The protocol study will focus on the seroprevalence of IgG antibodies to SARS-CoV-2 achieved by vaccination and/or natural protection as well as the history, symptoms, and risk factors for SARS-CoV-2 in four primary health-care workers (PHCWs) and their household contacts in metropolitan France. Methods: Here, we propose a protocol for a nationwide survey to determine the seroprevalence of IgG antibodies to SARS-CoV-2 achieved by vaccination and/or natural protection in four PHCW populations (general practitioners, pediatricians, pharmacists and assistants, and dentists and assistants) and their household contacts. Participants will be included from June to July 2021 (Phase 1) among PHCW populations located throughout metropolitan France. They will be asked to provide a range of demographic and behavioral information since the first SARS-CoV-2 wave and a self-sampled dried blood spot. Phase 1 will involve also a questionnaire and serological study of PHCWs’ household contacts. Seroprevalence will be estimated using two ELISAs designed to detect specific IgG antibodies to SARS-CoV-2 in humoral fluid, and these results will be confirmed using a virus neutralization test. This study will be repeated from November to December 2021 (Phase 2) to evaluate the evolution of immune status achieved by vaccination and/or natural protection of PHCWs and to describe the history of exposure to SARS-CoV-2.
The co‐occurrence of mtDNA mutations on different oxidative phosphorylation subunits, not detected by haplogroup analysis, affects human longevity and is population specific
Summary To re‐examine the correlation between mtDNA variability and longevity, we examined mtDNAs from samples obtained from over 2200 ultranonagenarians (and an equal number of controls) collected within the framework of the GEHA EU project. The samples were categorized by high‐resolution classification, while about 1300 mtDNA molecules (650 ultranonagenarians and an equal number of controls) were completely sequenced. Sequences, unlike standard haplogroup analysis, made possible to evaluate for the first time the cumulative effects of specific, concomitant mtDNA mutations, including those that per se have a low, or very low, impact. In particular, the analysis of the mutations occurring in different OXPHOS complex showed a complex scenario with a different mutation burden in 90+ subjects with respect to controls. These findings suggested that mutations in subunits of the OXPHOS complex I had a beneficial effect on longevity, while the simultaneous presence of mutations in complex I and III (which also occurs in J subhaplogroups involved in LHON) and in complex I and V seemed to be detrimental, likely explaining previous contradictory results. On the whole, our study, which goes beyond haplogroup analysis, suggests that mitochondrial DNA variation does affect human longevity, but its effect is heavily influenced by the interaction between mutations concomitantly occurring on different mtDNA genes.
Long-lasting symptoms after an acute COVID-19 infection and factors associated with their resolution
IMPORTANCE Persistent symptoms after SARS-CoV-2 infection are an emerging public health problem. The duration of these symptoms remains poorly documented. OBJECTIVE To describe the temporal dynamics of persistent symptoms after SARS-CoV-2 infection and the factors associated with their resolution.DESIGN, SETTING, AND PARTICIPANTS This cross-sectional study involved 53 047 participants from 3 French adult population-based cohorts (CONSTANCES [Consultants des Centres d’Examens de Santé], E3N/E4N, and Nutrinet-Santé) who were included in a nationwide survey about SARSCoV-2 infection. All participants were asked to complete self-administered questionnaires between April 1 and June 30, 2020. Variables included sociodemographic characteristics, comorbid conditions, COVID-19 diagnosis, and acute symptoms. Blood samples were obtained for serologic analysis between May 1 and November 30, 2020, from patients with SARS-CoV-2 infection defined as enzyme-linked immunosorbent assay immunoglobulin G antispike detection confirmed with a neutralization assay. A follow-up internet questionnaire was completed between June 1 and September 30, 2021, with details on persistent symptoms, their duration, and SARS-CoV-2 infection diagnosis by polymerase chain reaction.MAIN OUTCOMES AND MEASURES Persistent symptoms were defined as symptoms occurring during the acute infection and lasting 2 or more months. Survival models for interval-censored data were used to estimate symptom duration from the acute episode. Multivariable adjusted hazardratios (HRs) were estimated for age, sex, and comorbid conditions. Factors associated with the resolution of symptoms were assessed.RESULTS A total of 3972 participants (2531 women [63.7%; 95% CI, 62.2%-65.2%]; mean [SD] age, 50.9 [12.7] years) had been infected with SARS-CoV-2. Of these 3972 participants, 2647 (66.6% [95% CI, 65.1%-68.1%]) reported at least 1 symptom during the acute phase. Of these 2647participants, 861 (32.5% [95% CI, 30.8%-34.3%]) reported at least 1 persistent symptom lasting 2 or more months after the acute phase. After 1 year of follow-up, the estimated proportion of individuals with complete symptom resolution was 89.9% (95% CI, 88.7%-90.9%) with acute symptoms. Older age (>60 years; HR, 0.78; 95% CI, 0.68-0.90), female sex (HR, 0.64; 95% CI, 0.58-0.70), history of cancer (HR, 0.61; 95% CI, 0.47-0.79), history of tobacco consumption (HR, 0.80; 95% CI, 0.73-0.88), high body mass index (30: HR, 0.75; 95% CI, 0.63-0.89), and high number of symptoms during the acute phase (>4; HR, 0.43; 95% CI, 0.39-0.48) were associated with a slower resolution of symptoms.CONCLUSIONS AND RELEVANCE In this cross-sectional study, persistent symptoms were still present in 10.1% of infected individuals at 1 year after SARS-CoV-2 infection. Given the high level of cumulative incidence of COVID-19, the absolute prevalent number of people with persistentsymptoms is a public health concern.