RESUMEN
Human APOE is a 299-amino acid long protein expressed and secreted in several tissues and body districts, where it exerts different functions mainly related to lipid metabolism, with specific activities around cholesterol transport and absorption/elimination. It has three main isoforms, determined by the pair of mutations rs7412-C/T and rs429358-C/T, which gives rise to the functionally different APOE variants ε2, ε3, and ε4. These have a distinct impact on lipid metabolism and are differentially implicated in Alzheimer's disease and neurodegeneration, cardiovascular disease, and dyslipidemia. A plethora of other single nucleotide variants along the sequence of the APOE gene have been studied in cohorts of affected individuals, where they also modulate the influence of the three main isoforms to determine the risk of developing the disease. However, no contextual analysis of gene-long haplotypes has been carried out so far, and never extensively in cohorts of healthy individuals from different worldwide populations. Leveraging a rich population genomics dataset, this study elucidates the distribution of APOE variants and haplotypes that are shared across populations and to specific macroareas, revealing a variety of risk-allele associations that distinguish specific ancestral backgrounds and can be leveraged for specific ancestry-informed screenings in medicine and public health.
RESUMEN
Cardiovascular diseases are the leading cause of global deaths, and many risk factors contribute to their pathogenesis. In this context, prostanoids, which derive from arachidonic acid, have attracted attention for their involvement in cardiovascular homeostasis and inflammatory processes. Prostanoids are the target of several drugs, but it has been shown that some of them increase the risk of thrombosis. Overall, many studies have shown that prostanoids are tightly associated with cardiovascular diseases and that several polymorphisms in genes involved in their synthesis and function increase the risk of developing these pathologies. In this review, we focus on molecular mechanisms linking prostanoids to cardiovascular diseases and we provide an overview of genetic polymorphisms that increase the risk for cardiovascular disease.
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Enfermedades Cardiovasculares , Sistema Cardiovascular , Trombosis , Humanos , Prostaglandinas , Factores de RiesgoRESUMEN
Alzheimer's disease (AD) represents the most prevalent type of dementia in elderly people, primarily characterized by brain accumulation of beta-amyloid (Aß) peptides, derived from Amyloid Precursor Protein (APP), in the extracellular space (amyloid plaques) and intracellular deposits of the hyperphosphorylated form of the protein tau (p-tau; tangles or neurofibrillary aggregates). The Nerve growth factor receptor (NGFR/p75NTR) represents a low-affinity receptor for all known mammalians neurotrophins (i.e., proNGF, NGF, BDNF, NT-3 e NT-4/5) and it is involved in pathways that determine both survival and death of neurons. Interestingly, also Aß peptides can blind to NGFR/p75NTR making it the "ideal" candidate in mediating Aß-induced neuropathology. In addition to pathogenesis and neuropathology, several data indicated that NGFR/p75NTR could play a key role in AD also from a genetic perspective. Other studies suggested that NGFR/p75NTR could represent a good diagnostic tool, as well as a promising therapeutic target for AD. Here, we comprehensively summarize and review the current experimental evidence on this topic.
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Enfermedad de Alzheimer , Anciano , Animales , Humanos , Enfermedad de Alzheimer/metabolismo , Péptidos beta-Amiloides/metabolismo , Mamíferos/metabolismo , Factor de Crecimiento Nervioso/farmacología , Proteínas del Tejido Nervioso , Receptor de Factor de Crecimiento Nervioso/metabolismo , Receptores de Factor de Crecimiento Nervioso/metabolismo , Proteínas tau/metabolismoRESUMEN
In the U.S., more than 80% of African-American smokers use mentholated cigarettes, compared to less than 30% of Caucasian smokers. The reasons for these differences are not well understood. To determine if genetic variation contributes to mentholated cigarette smoking, we performed an exome-wide association analysis in a multiethnic population-based sample from Dallas, TX (N = 561). Findings were replicated in an independent cohort of African Americans from Washington, DC (N = 741). We identified a haplotype of MRGPRX4 (composed of rs7102322[G], encoding N245S, and rs61733596[G], T43T), that was associated with a 5-to-8 fold increase in the odds of menthol cigarette smoking. The variants are present solely in persons of African ancestry. Functional studies indicated that the variant G protein-coupled receptor encoded by MRGPRX4 displays reduced agonism in both arrestin-based and G protein-based assays, and alteration of agonism by menthol. These data indicate that genetic variation in MRGPRX4 contributes to inter-individual and inter-ethnic differences in the preference for mentholated cigarettes, and that the existence of genetic factors predisposing vulnerable populations to mentholated cigarette smoking can inform tobacco control and public health policies.
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Negro o Afroamericano/genética , Fumar Cigarrillos/genética , Haplotipos/genética , Mentol , Receptores Acoplados a Proteínas G/genética , Adulto , Estudios de Cohortes , Femenino , Variación Genética/genética , Humanos , Masculino , Persona de Mediana Edad , Fumar/efectos adversos , Nicotiana/efectos adversosRESUMEN
Genetic discoveries related to Alzheimer's disease and other dementias have been performed using either large cohorts of affected subjects or multiple individuals from the same pedigree, therefore disregarding mutations in the context of healthy groups. Moreover, a large portion of studies so far have been performed on individuals of European ancestry, with a remarkable lack of epidemiological and genomic data from underrepresented populations. In the present study, 70 single-point mutations on the APP gene in a publicly available genetic dataset that included 2504 healthy individuals from 26 populations were scanned, and their distribution was analyzed. Furthermore, after gametic phase reconstruction, a pairwise comparison of the segments surrounding the mutations was performed to reveal patterns of haplotype sharing that could point to specific cross-population and cross-ancestry admixture events. Eight mutations were detected in the worldwide dataset, with several of them being specific for a single individual, population, or macroarea. Patterns of segment sharing reflected recent historical events of migration and admixture possibly linked to colonization campaigns. These observations reveal the population dynamics of the considered APP mutations in worldwide human groups and support the development of ancestry-informed screening practices for the improvement of precision and personalized approaches to neurodegeneration and dementia.
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Precursor de Proteína beta-Amiloide , Genética de Población , Migración Humana , Humanos , Enfermedad de Alzheimer/genética , Precursor de Proteína beta-Amiloide/genética , Mutación , Mutación Puntual , Dinámica PoblacionalRESUMEN
The high number of matching haplotypes of the most common mitochondrial (mt)DNA lineages are considered to be the greatest limitation for forensic applications. This study investigates the potential to solve this constraint by massively parallel sequencing a large number of mitogenomes that share the most common West Eurasian mtDNA control region (CR) haplotype motif (263G 315.1C 16519C). We augmented a pilot study on 29 to a total of 216 Italian mitogenomes that represents the largest set of the most common CR haplotype compiled from a single country. The extended population sample confirmed and extended the huge coding region diversity behind the most common CR motif. Complete mitogenome sequencing allowed for the detection of 163 distinct haplotypes, raising the power of discrimination from 0 (CR) to 99.6% (mitogenome). The mtDNAs were clustered into 61 named clades of haplogroup H and did not reveal phylogeographic trends within Italy. Rapid individualization approaches for investigative purposes are limited to the most frequent H clades of the dataset, viz. H1, H3, and H7.
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ADN Mitocondrial , Genoma Mitocondrial , ADN Mitocondrial/genética , Genética de Población , Haplotipos/genética , Núcleo Familiar , Proyectos Piloto , Análisis de Secuencia de ADNRESUMEN
Eritrea is a multi-ethnic country of over 3 million of people consisting of different ethnic groups, having each its own language and cultural tradition. Due to the lack of population genetic data for markers of forensic interest, in this study, we analyzed the genetic polymorphisms of 23 Y-chromosome STR loci and of 12 X-chromosome STR loci in a sample of 255 unrelated individuals from 8 Eritrean ethnic groups, with the aim to generate a reference haplotype database for anthropological and forensic applications. X- and Y-chromosomes markers may indeed offer information especially in personal identification and kinship testing, when relying on the availability of large local population data to derive sufficiently accurate frequency estimates. The population genetic analyses in the Eritrean sample for both the two set of Y- and X-STR markers showed high power of discrimination both at country-based and population levels. Comparison population results highlight the importance of considering the ethnic composition within the analyzed country and the necessity of increasing available data especially when referring to heterogeneous populations such as the African ones.
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Cromosomas Humanos X/genética , Cromosomas Humanos Y/genética , Etnicidad/genética , Genética de Población , Haplotipos , Repeticiones de Microsatélite , Bases de Datos Genéticas , Eritrea/etnología , Humanos , Masculino , Polimorfismo GenéticoRESUMEN
With the recent advances in next-generation sequencing (NGS), mitochondrial whole-genome sequencing has begun to be applied to the field of the forensic biology as an alternative to the traditional Sanger-type sequencing (STS). However, experimental workflows, commercial solutions, and output data analysis must be strictly validated before being implemented into the forensic laboratory. In this study, we performed an internal validation for an NGS-based typing of the entire mitochondrial genome using the Precision ID mtDNA Whole Genome Panel (Thermo Fisher Scientific) on the Ion S5 sequencer (Thermo Fisher Scientific). Concordance, repeatability, reproducibility, sensitivity, and heteroplasmy detection analyses were assessed using the 2800 M and 9947A standard control DNA as well as typical casework specimens, and results were compared with conventional Sanger sequencing and another NGS sequencer in a different laboratory. We discuss the strengths and limitations of this approach, highlighting some issues regarding noise thresholds and heteroplasmy detection, and suggesting solutions to mitigate these effects and improve overall data interpretation. Results confirmed that the Precision ID Whole mtDNA Genome Panel is highly reproducible and sensitive, yielding useful full mitochondrial DNA sequences also from challenging DNA specimens, thus providing further support for its use in forensic practice.
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Genoma Mitocondrial , ADN Mitocondrial/genética , Haplotipos , Secuenciación de Nucleótidos de Alto Rendimiento/métodos , Humanos , Reproducibilidad de los Resultados , Análisis de Secuencia de ADN/métodosRESUMEN
BACKGROUND: The cline of human genetic diversity observable across Europe is recapitulated at a micro-geographic scale by variation within the Italian population. Besides resulting from extensive gene flow, this might be ascribable also to local adaptations to diverse ecological contexts evolved by people who anciently spread along the Italian Peninsula. Dissecting the evolutionary history of the ancestors of present-day Italians may thus improve the understanding of demographic and biological processes that contributed to shape the gene pool of European populations. However, previous SNP array-based studies failed to investigate the full spectrum of Italian variation, generally neglecting low-frequency genetic variants and examining a limited set of small effect size alleles, which may represent important determinants of population structure and complex adaptive traits. To overcome these issues, we analyzed 38 high-coverage whole-genome sequences representative of population clusters at the opposite ends of the cline of Italian variation, along with a large panel of modern and ancient Euro-Mediterranean genomes. RESULTS: We provided evidence for the early divergence of Italian groups dating back to the Late Glacial and for Neolithic and distinct Bronze Age migrations having further differentiated their gene pools. We inferred adaptive evolution at insulin-related loci in people from Italian regions with a temperate climate, while possible adaptations to pathogens and ultraviolet radiation were observed in Mediterranean Italians. Some of these adaptive events may also have secondarily modulated population disease or longevity predisposition. CONCLUSIONS: We disentangled the contribution of multiple migratory and adaptive events in shaping the heterogeneous Italian genomic background, which exemplify population dynamics and gene-environment interactions that played significant roles also in the formation of the Continental and Southern European genomic landscapes.
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Evolución Molecular , Variación Genética , Genoma Humano , Arqueología , ADN Antiguo/análisis , Humanos , Italia , Población BlancaRESUMEN
BACKGROUND: Phoenician and Punic expansions have been protagonists of intense trade networks and settlements in the Mediterranean Sea. AIMS: The maternal genetic variability of ancient Punic samples from the Sardinian necropolis of Tharros was analysed, with the aim to explore genetic interactions and signatures of past population events. SUBJECTS AND METHODS: The mtDNA HVS-I and coding region SNPs were analysed in 14 Punic samples and 74 modern individuals from Cabras and Belvì (for which the HVS-II region was also analysed). The results were compared with 5,590 modern Euro-Mediterranean sequences and 127 ancient samples. RESULTS: While contemporary groups fall within the genetic variability of other modern Sardinians, our Punic samples reveal proximity to present-day North-African and Iberian populations. Furthermore, Cabras and Belvì cluster mainly with pre-Phoenician groups, while samples from Tharros project with other Punic Sardinian individuals. CONCLUSION: This study provides the first preliminary insights into the population dynamics of the Punic site of Tharros. While the number of currently available samples does not allow definitive investigation of the connection with indigenous Sardinian groups, our results seem to confirm internal migratory phenomena in the central-western Mediterranean and female participation in the Punic mobility.
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ADN Antiguo/análisis , ADN Mitocondrial/análisis , Variación Genética , Migración Humana , Niño , Preescolar , Femenino , Humanos , Lactante , Recién Nacido , Italia , Masculino , Dinámica Poblacional , TúnezRESUMEN
Music is an exclusive feature of humankind. It can be considered as a form of universal communication, only partly comparable to the vocalizations of songbirds. Many trends of research in this field try to address music origins, as well as the genetic bases of musicality. On one hand, several hypotheses have been made on the evolution of music and its role, but there is still debate, and comparative studies suggest a gradual evolution of some abilities underlying musicality in primates. On the other hand, genome-wide studies highlight several genes associated with musical aptitude, confirming a genetic basis for different musical skills which humans show. Moreover, some genes associated with musicality are involved also in singing and song learning in songbirds, suggesting a likely evolutionary convergence between humans and songbirds. This comprehensive review aims at presenting the concept of music as a sociocultural manifestation within the current debate about its biocultural origin and evolutionary function, in the context of the most recent discoveries related to the cross-species genetics of musical production and perception.
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Genoma Humano/genética , Animales , Evolución Biológica , Genómica/métodos , Humanos , MúsicaRESUMEN
Extensive European and African admixture coupled with loss of Amerindian lineages makes the reconstruction of pre-Columbian history of Native Americans based on present-day genomes extremely challenging. Still open questions remain about the dispersals that occurred throughout the continent after the initial peopling from the Beringia, especially concerning the number and dynamics of diffusions into South America. Indeed, if environmental and historical factors contributed to shape distinct gene pools in the Andes and Amazonia, the origins of this East-West genetic structure and the extension of further interactions between populations residing along this divide are still not well understood. To this end, we generated new high-resolution genome-wide data for 229 individuals representative of one Central and ten South Amerindian ethnic groups from Mexico, Peru, Bolivia, and Argentina. Low levels of European and African admixture in the sampled individuals allowed the application of fine-scale haplotype-based methods and demographic modeling approaches. These analyses revealed highly specific Native American genetic ancestries and great intragroup homogeneity, along with limited traces of gene flow mainly from the Andes into Peruvian Amazonians. Substantial amount of genetic drift differentially experienced by the considered populations underlined distinct patterns of recent inbreeding or prolonged isolation. Overall, our results support the hypothesis that all non-Andean South Americans are compatible with descending from a common lineage, while we found low support for common Mesoamerican ancestors of both Andeans and other South American groups. These findings suggest extensive back-migrations into Central America from non-Andean sources or conceal distinct peopling events into the Southern Continent.
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Genoma Humano , Migración Humana , Indígenas Sudamericanos/genética , Flujo Génico , Variación Genética , Haplotipos , Humanos , Modelos Genéticos , Filogeografía , Polimorfismo de Nucleótido Simple , Análisis de Componente Principal , América del SurRESUMEN
Observable patterns of cultural variation are consistently intertwined with demic movements, cultural diffusion, and adaptation to different ecological contexts [Cavalli-Sforza and Feldman (1981) Cultural Transmission and Evolution: A Quantitative Approach; Boyd and Richerson (1985) Culture and the Evolutionary Process]. The quantitative study of gene-culture coevolution has focused in particular on the mechanisms responsible for change in frequency and attributes of cultural traits, the spread of cultural information through demic and cultural diffusion, and detecting relationships between genetic and cultural lineages. Here, we make use of worldwide whole-genome sequences [Pagani et al. (2016) Nature 538:238-242] to assess the impact of processes involving population movement and replacement on cultural diversity, focusing on the variability observed in folktale traditions (n = 596) [Uther (2004) The Types of International Folktales: A Classification and Bibliography. Based on the System of Antti Aarne and Stith Thompson] in Eurasia. We find that a model of cultural diffusion predicted by isolation-by-distance alone is not sufficient to explain the observed patterns, especially at small spatial scales (up to [Formula: see text]4,000 km). We also provide an empirical approach to infer presence and impact of ethnolinguistic barriers preventing the unbiased transmission of both genetic and cultural information. After correcting for the effect of ethnolinguistic boundaries, we show that, of the alternative models that we propose, the one entailing cultural diffusion biased by linguistic differences is the most plausible. Additionally, we identify 15 tales that are more likely to be predominantly transmitted through population movement and replacement and locate putative focal areas for a set of tales that are spread worldwide.
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Evolución Cultural , Folclore , Genética de Población/métodos , Genómica/métodos , África , Asia , Evolución Biológica , Europa (Continente) , Geografía , Humanos , Lingüística , Modelos TeóricosRESUMEN
OBJECTIVES: The Yaghnobis are an ethno-linguistic minority historically settled along the Yaghnob River in the Upper-Zarafshan Valley in Tajikistan. They speak a language of Old Sogdian origin, which is the only present-day witness of the Lingua Franca used along the Silk Road in Late Antiquity. The aim of this study was to reconstruct the genetic history of this community in order to shed light on its isolation and genetic ancestry within the Euro-Asiatic context. MATERIALS AND METHODS: A total of 100 DNA samples were collected in the Yaghnob and Matcha Valleys during several expeditions and their mitochondrial, Y-chromosome and autosomal genome-wide variation were compared with that from a large set of modern and ancient Euro-Asiatic samples. RESULTS: Findings from uniparental markers highlighted the long-term isolation of the Yaghnobis. Mitochondrial DNA ancestry traced an ancient link with Middle Eastern populations, whereas Y-chromosome legacy showed more tight relationships with Central Asians. Admixture, outgroup-f3, and D-statistics computed on autosomal variation corroborated Y-chromosome evidence, pointing respectively to low Anatolian Neolithic and high Steppe ancestry proportions in Yaghnobis, and to their closer affinity with Tajiks than to Iranians. DISCUSSION: Although the Yaghnobis do not show evident signs of recent admixture, they could be considered a modern proxy for the source of gene flow for many Central Asian and Middle Eastern groups. Accordingly, they seem to retain a peculiar genomic ancestry probably ascribable to an ancient gene pool originally wide spread across a vast area and subsequently reshuffled by distinct demographic events occurred in Middle East and Central Asia.
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Pueblo Asiatico/genética , Etnicidad/genética , Población Blanca/genética , Antropología Física , Cromosomas Humanos Y/genética , ADN Mitocondrial/genética , Migración Humana , Humanos , Masculino , Metagenómica , Polimorfismo de Nucleótido Simple/genética , TayikistánRESUMEN
The predominantly African origin of all modern human populations is well established, but the route taken out of Africa is still unclear. Two alternative routes, via Egypt and Sinai or across the Bab el Mandeb strait into Arabia, have traditionally been proposed as feasible gateways in light of geographic, paleoclimatic, archaeological, and genetic evidence. Distinguishing among these alternatives has been difficult. We generated 225 whole-genome sequences (225 at 8× depth, of which 8 were increased to 30×; Illumina HiSeq 2000) from six modern Northeast African populations (100 Egyptians and five Ethiopian populations each represented by 25 individuals). West Eurasian components were masked out, and the remaining African haplotypes were compared with a panel of sub-Saharan African and non-African genomes. We showed that masked Northeast African haplotypes overall were more similar to non-African haplotypes and more frequently present outside Africa than were any sets of haplotypes derived from a West African population. Furthermore, the masked Egyptian haplotypes showed these properties more markedly than the masked Ethiopian haplotypes, pointing to Egypt as the more likely gateway in the exodus to the rest of the world. Using five Ethiopian and three Egyptian high-coverage masked genomes and the multiple sequentially Markovian coalescent (MSMC) approach, we estimated the genetic split times of Egyptians and Ethiopians from non-African populations at 55,000 and 65,000 years ago, respectively, whereas that of West Africans was estimated to be 75,000 years ago. Both the haplotype and MSMC analyses thus suggest a predominant northern route out of Africa via Egypt.
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Evolución Biológica , Población Negra/genética , Genoma Humano/genética , Migración Humana/historia , Secuencia de Bases , Antiguo Egipto , Etiopía , Geografía , Haplotipos/genética , Secuenciación de Nucleótidos de Alto Rendimiento/métodos , Historia Antigua , Humanos , Cadenas de Markov , Modelos Genéticos , Datos de Secuencia Molecular , Análisis de Componente PrincipalRESUMEN
BACKGROUND: Southern Italy and Sicily played a key role in the peopling history of the Mediterranean. While genetic research showed the remarkable homogeneity of these regions, surname-based studies instead suggested low population mobility, hence potential structuring. AIM: In order to better understand these different patterns, this study (1) thoroughly analysed the surname structure of Sicily and Southern Italy and (2) tested its relationships with a wide set of molecular markers. SUBJECTS AND METHODS: Surname data were collected from 1213 municipalities and compared to uniparental and autosomal genetic markers typed in â¼300 individuals from 8-10 populations. Surname analyses were performed using different multivariate methods, while comparisons with genetic data relied on correlation tests. RESULTS: Surnames were clearly structured according to regional geographic patterns, which likely emerged because of recent isolation-by-distance-like population dynamics. In general, genetic markers, hinting at a pervasive homogeneity, did not correlate with surname distribution. However, long autosomal haplotypes (>5 cM) that compared to genotypic (SNPs) data identify more "recent" relatedness, showing a clear association with surname patterns. CONCLUSION: The apparent contradiction between surname structure and genetic homogeneity was resolved by figuring surnames as recent "ripples" deposited on a vast and ancient homogeneous genetic "surface".
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Variación Genética , Haplotipos , Dinámica Poblacional , Marcadores Genéticos , Humanos , Italia , Nombres , SiciliaRESUMEN
BACKGROUND: Environmental conditions and past migratory events may have shaped genetic heterogeneity of clinically relevant enzymes involved in the phase I metabolism of the most common therapeutic drugs. AIM: To investigate the genetic variability of CYP2D6, CYP2B6, CYP2C19 and CYP2C9 across the Italian Peninsula, by sampling only ancestrally and geographically homogeneous individuals from northern, central and southern Italy. SUBJECTS AND METHODS: A total of 25 SNPs were genotyped in 174 unrelated Italian individuals by means of multiplex PCR and minisequencing reactions. CYP2D6 genotypic data were used to predict phenotypes and the phylogenetic relationships among reconstructed haplotypes were represented by means of a Median Joining Network. RESULTS: Pairwise Fisher Exact tests revealed significant differences between northern and southern Italy in the distribution of CYP2C19 genotypes, with the CYP2C19*2 allele appearing over-represented in northern Italy. Likewise, significant differences in the distribution of CYP2D6 genotypes (*4/*3, *4/*4 and *6/*4) responsible for the poor metabolizer phenotype were observed in northern with respect to both central and southern Italy. CONCLUSIONS: The north-south structuring pattern showed by CYP2D6 and CYP2C19 underline how a deeper knowledge of the geographic distribution of alleles may improve clinical practice and help to avoid hypothetical bias in drug trials.
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Familia 2 del Citocromo P450/genética , Frecuencia de los Genes , Polimorfismo Genético , Citocromo P-450 CYP2B6/genética , Citocromo P-450 CYP2C19/genética , Citocromo P-450 CYP2C9/genética , Citocromo P-450 CYP2D6/genética , Humanos , ItaliaRESUMEN
BACKGROUND: Archaeological data provide evidence that Italy, during the Iron Age, witnessed the appearance of the first communities with well defined cultural identities. To date, only a few studies report genetic data about these populations and, in particular, the Piceni have never been analysed. AIMS: To provide new data about mitochondrial DNA (mtDNA) variability of an Iron Age Italic population, to understand the contribution of the Piceni in shaping the modern Italian gene pool and to ascertain the kinship between some individuals buried in the same grave within the Novilara necropolis. SUBJECTS AND METHODS: In a first set of 10 individuals from Novilara, we performed deep sequencing of the HVS-I region of the mtDNA, combined with the genotyping of 22 SNPs in the coding region and the analysis of several autosomal markers. RESULTS: The results show a low nucleotide diversity for the inhabitants of Novilara and highlight a genetic affinity of this ancient population with the current inhabitants of central Italy. No family relationship was observed between the individuals analysed here. CONCLUSIONS: This study provides a preliminary characterisation of the mtDNA variability of the Piceni of Novilara, as well as a kinship assessment of two peculiar burials.
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ADN Mitocondrial/análisis , Variación Genética , Haplotipos , Polimorfismo de Nucleótido Simple , Arqueología , ADN Antiguo/análisis , Femenino , Humanos , Italia , MasculinoRESUMEN
STUDY QUESTION: Does selection for mtDNA mutations occur in human oocytes? SUMMARY ANSWER: We provide statistical evidence in favor of the existence of purifying selection for mtDNA mutations in human oocytes acting between the expulsion of the first and second polar bodies (PBs). WHAT IS KNOWN ALREADY: Several lines of evidence in Metazoa, including humans, indicate that variation within the germline of mitochondrial genomes is under purifying selection. The presence of this internal selection filter in the germline has important consequences for the evolutionary trajectory of mtDNA. However, the nature and localization of this internal filter are still unclear while several hypotheses are proposed in the literature. STUDY DESIGN, SIZE, DURATION: In this study, 60 mitochondrial genomes were sequenced from 17 sets of oocytes, first and second PBs, and peripheral blood taken from nine women between 38 and 43 years of age. PARTICIPANTS/MATERIALS, SETTING, METHODS: Whole genome amplification was performed only on the single cell samples and Sanger sequencing was performed on amplicons. The comparison of variant profiles between first and second PB sequences showed no difference in substitution rates but displayed instead a sharp difference in pathogenicity scores of protein-coding sequences using three different metrics (MutPred, Polyphen and SNPs&GO). MAIN RESULTS AND THE ROLE OF CHANCE: Unlike the first, second PBs showed no significant differences in pathogenic scores with blood and oocyte sequences. This suggests that a filtering mechanism for disadvantageous variants operates during oocyte development between the expulsion of the first and second PB. LARGE SCALE DATA: N/A. LIMITATIONS, REASONS FOR CAUTION: The sample size is small and further studies are needed before this approach can be used in clinical practice. Studies on a model organism would allow the sample size to be increased. WIDER IMPLICATIONS OF THE FINDINGS: This work opens the way to the study of the correlation between mtDNA mutations, mitochondrial capacity and viability of oocytes. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by a SISMER grant. Laboratory facilities and skills were freely provided by SISMER, and by the Alma Mater Studiorum, University of Bologna. The authors have no conflict of interest to disclose.
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ADN Mitocondrial/genética , Mitocondrias/genética , Mutación , Oocitos/metabolismo , Oogénesis/genética , Adulto , Femenino , Genoma Mitocondrial , Humanos , Oocitos/citologíaRESUMEN
The study of food choice, one of the most complex human traits, requires an integrated approach that takes into account environmental, socio-cultural and biological diversity. We recruited 183 volunteers from four geo-linguistic groups and highly diversified in terms of both genetic background and food habits from whom we collected genotypes and phenotypes tightly linked to taste perception. We confirmed previous genetic associations, in particular with stevioside perception, and noted significant differences in food consumption: in particular, broccoli, mustard and beer consumption scores were significantly higher (Adjusted P = 0.02, Adjusted P < 0.0001 and Adjusted P = 0.01, respectively) in North Europeans, when compared to the other groups. Licorice and Parmesan cheese showed lower consumption and liking scores in the Sri Lankan group (Adjusted P = 0.001 and Adjusted P < 0.001, respectively). We also highlighted how rs860170 (TAS2R16) strongly differentiated populations and was associated to salicin bitterness perception. Identifying genetic variants on chemosensory receptors that vary across populations and show associations with taste perception and food habits represents a step towards a better comprehension of this complex trait, aimed at improving the individual health status. This is the first study that concurrently explores the contribution of genetics, population diversity and cultural aspects in taste perception and food consumption.