Publications by authors named "Silvia Fuselli"

16 Publications

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The genetic structure and adaptation of Andean highlanders and Amazonians are influenced by the interplay between geography and culture.

Proc Natl Acad Sci U S A 2020 12 4;117(51):32557-32565. Epub 2020 Dec 4.

Laboratorio de Biotecnología y Biología Molecular, Instituto Nacional de Salud, Lima 9, Peru;

Western South America was one of the worldwide cradles of civilization. The well-known Inca Empire was the tip of the iceberg of an evolutionary process that started 11,000 to 14,000 years ago. Genetic data from 18 Peruvian populations reveal the following: 1) The between-population homogenization of the central southern Andes and its differentiation with respect to Amazonian populations of similar latitudes do not extend northward. Instead, longitudinal gene flow between the northern coast of Peru, Andes, and Amazonia accompanied cultural and socioeconomic interactions revealed by archeology. This pattern recapitulates the environmental and cultural differentiation between the fertile north, where altitudes are lower, and the arid south, where the Andes are higher, acting as a genetic barrier between the sharply different environments of the Andes and Amazonia. 2) The genetic homogenization between the populations of the arid Andes is not only due to migrations during the Inca Empire or the subsequent colonial period. It started at least during the earlier expansion of the Wari Empire (600 to 1,000 years before present). 3) This demographic history allowed for cases of positive natural selection in the high and arid Andes vs. the low Amazon tropical forest: in the Andes, a putative enhancer in (heart and neural crest derivatives expressed 2 antisense RNA1, a noncoding gene related to cardiovascular function) and rs269868-C/Ser1067 in (dual oxidase 2, related to thyroid function and innate immunity) genes and, in the Amazon, the gene encoding for the CD45 protein, essential for antigen recognition by T and B lymphocytes in viral-host interaction.
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http://dx.doi.org/10.1073/pnas.2013773117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7768732PMC
December 2020

Beyond drugs: the evolution of genes involved in human response to medications.

Authors:
Silvia Fuselli

Proc Biol Sci 2019 10 23;286(1913):20191716. Epub 2019 Oct 23.

Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy.

The genetic variation of our species reflects human demographic history and adaptation to diverse local environments. Part of this genetic variation affects individual responses to exogenous substances, such as food, pollutants and drugs, and plays an important role in drug efficacy and safety. This review provides a synthesis of the evolution of loci implicated in human pharmacological response and metabolism, interpreted within the theoretical framework of population genetics and molecular evolution. In particular, I review and discuss key evolutionary aspects of different pharmacogenes in humans and other species, such as the relationship between the type of substrates and rate of evolution; the selective pressure exerted by landscape variables or dietary habits; expected and observed patterns of rare genetic variation. Finally, I discuss how this knowledge can be translated directly or after the implementation of specific studies, into practical guidelines.
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http://dx.doi.org/10.1098/rspb.2019.1716DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6834052PMC
October 2019

Mutations in blind cavefish target the light-regulated circadian clock gene, period 2.

Sci Rep 2018 06 8;8(1):8754. Epub 2018 Jun 8.

Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany.

Light represents the principal signal driving circadian clock entrainment. However, how light influences the evolution of the clock remains poorly understood. The cavefish Phreatichthys andruzzii represents a fascinating model to explore how evolution under extreme aphotic conditions shapes the circadian clock, since in this species the clock is unresponsive to light. We have previously demonstrated that loss-of-function mutations targeting non-visual opsins contribute in part to this blind clock phenotype. Here, we have compared orthologs of two core clock genes that play a key role in photic entrainment, cry1a and per2, in both zebrafish and P. andruzzii. We encountered aberrantly spliced variants for the P. andruzzii per2 transcript. The most abundant transcript encodes a truncated protein lacking the C-terminal Cry binding domain and incorporating an intronic, transposon-derived coding sequence. We demonstrate that the transposon insertion leads to a predominantly cytoplasmic localization of the cavefish Per2 protein in contrast to the zebrafish ortholog which is distributed in both the nucleus and cytoplasm. Thus, it seems that during evolution in complete darkness, the photic entrainment pathway of the circadian clock has been subject to mutation at multiple levels, extending from opsin photoreceptors to nuclear effectors.
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http://dx.doi.org/10.1038/s41598-018-27080-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5993827PMC
June 2018

Survival and divergence in a small group: The extraordinary genomic history of the endangered Apennine brown bear stragglers.

Proc Natl Acad Sci U S A 2017 11 24;114(45):E9589-E9597. Epub 2017 Oct 24.

Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy;

About 100 km east of Rome, in the central Apennine Mountains, a critically endangered population of ∼50 brown bears live in complete isolation. Mating outside this population is prevented by several 100 km of bear-free territories. We exploited this natural experiment to better understand the gene and genomic consequences of surviving at extremely small population size. We found that brown bear populations in Europe lost connectivity since Neolithic times, when farming communities expanded and forest burning was used for land clearance. In central Italy, this resulted in a 40-fold population decline. The overall genomic impact of this decline included the complete loss of variation in the mitochondrial genome and along long stretches of the nuclear genome. Several private and deleterious amino acid changes were fixed by random drift; predicted effects include energy deficit, muscle weakness, anomalies in cranial and skeletal development, and reduced aggressiveness. Despite this extreme loss of diversity, Apennine bear genomes show nonrandom peaks of high variation, possibly maintained by balancing selection, at genomic regions significantly enriched for genes associated with immune and olfactory systems. Challenging the paradigm of increased extinction risk in small populations, we suggest that random fixation of deleterious alleles () can be an important driver of divergence in isolation, () can be tolerated when balancing selection prevents random loss of variation at important genes, and () is followed by or results directly in favorable behavioral changes.
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http://dx.doi.org/10.1073/pnas.1707279114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5692547PMC
November 2017

Human loci involved in drug biotransformation: worldwide genetic variation, population structure, and pharmacogenetic implications.

Hum Genet 2013 May 26;132(5):563-77. Epub 2013 Jan 26.

Department of Life Sciences and Biotechnologies, University of Ferrara, Ferrara, Italy.

Understanding the role of inheritance in individual variation in drug response is the focus of pharmacogenetics (PGx). A key part of this understanding is quantifying the role of genetic ancestry in this phenotypic outcome. To provide insight into the relationship between ethnicity and drug response, this study first infers the global distribution of PGx variation and defines its structure. Second, the study evaluates if geographic population structure stems from all PGx loci in general, or if structure is caused by specific genes. Lastly, we identify the genetic variants contributing the greatest proportion of such structure. Our study describes the global genetic structure of PGx loci across the 52 populations of the Human Genome Diversity Cell-Line Panel, the most inclusive set of human populations freely available for studies on human genetic variation. By analysing genetic variation at 1,001 single nucleotide polymorphisms (SNPs) involved in biotransformation of exogenous substances, we describe the between-populations PGx variation, as well geographical groupings of diversity. In addition, with discriminant analysis of principal component (DAPC), we infer how many and which groups of populations are supported by PGx variation, and identify which SNPs actually contribute to the PGx structure between such groups. Our results show that intergenic, synonymous and non-synonymous SNPs show similar levels of genetic variation across the globe. Conversely, loci coding for Cytochrome P450s (mainly metabolizing exogenous substances) show significantly higher levels of genetic diversity between populations than the other gene categories. Overall, genetic variation at PGx loci correlates with geographic distances between populations, and the apportionment of genetic variation is similar to that observed for the rest of the genome. In other words, the pattern of PGx variation has been mainly shaped by the demographic history of our species, as in the case of most of our genes. The population structure defined by PGx loci supports the presence of six genetic clusters reflecting geographic location of samples. In particular, the results of the DAPC analyses show that 27 SNPs substantially contribute to the first three discriminant functions. Among these SNPs, some, such as the intronic rs1403527 of NR1I2 and the non-synonymous rs699 of AGT, are known to be associated with specific drug responses. Their substantial variation between different groups of populations may have important implications for PGx practical applications.
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http://dx.doi.org/10.1007/s00439-013-1268-5DOI Listing
May 2013

Genetic structure of the Mon-Khmer speaking groups and their affinity to the neighbouring Tai populations in Northern Thailand.

BMC Genet 2011 Jun 15;12:56. Epub 2011 Jun 15.

Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.

Background: The Mon-Khmer speaking peoples inhabited northern Thailand before the arrival of the Tai speaking people from southern China in the thirteenth century A.D. Historical and anthropological evidence suggests a close relationship between the Mon-Khmer groups and the present day majority northern Thai groups. In this study, mitochondrial and Y-chromosomal DNA polymorphisms in more than 800 volunteers from eight Mon-Khmer and ten Tai speaking populations were investigated to estimate the degree of genetic divergence between these major linguistic groups and their internal structure.

Results: A large fraction of genetic variation is observed within populations (about 80% and 90% for mtDNA and the Y-chromosome, respectively). The genetic divergence between populations is much higher in Mon-Khmer than in Tai speaking groups, especially at the paternally inherited markers. The two major linguistic groups are genetically distinct, but only for a marginal fraction (1 to 2%) of the total genetic variation. Genetic distances between populations correlate with their linguistic differences, whereas the geographic distance does not explain the genetic divergence pattern.

Conclusions: The Mon-Khmer speaking populations in northern Thailand exhibited the genetic divergence among each other and also when compared to Tai speaking peoples. The different drift effects and the post-marital residence patterns between the two linguistic groups are the explanation for a small but significant fraction of the genetic variation pattern within and between them.
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http://dx.doi.org/10.1186/1471-2156-12-56DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3126721PMC
June 2011

BCHE and CYP2D6 genetic variation in Alzheimer's disease patients treated with cholinesterase inhibitors.

Eur J Clin Pharmacol 2011 Nov 1;67(11):1147-57. Epub 2011 Jun 1.

Department of Biology and Evolution, University of Ferrara, via Borsari 46, 44100 Ferrara, Italy.

Purpose: Cholinesterase inhibitors are commonly prescribed to patients with Alzheimer's disease (AD) to enhance cholinergic neurotransmission. Differential response to these treatments has been observed, and claims have been made that individual genetic variants may influence the pharmacokinetic and pharmacodynamic properties of these drugs. Here we assess the effects of genetic variation at two loci involved in the activity of cholinesterase inhibitors on longitudinal clinical change in AD patients being treated with donepezil, galantamine, and rivastigmine.

Methods: This was an open study in which 171 Italian AD patients treated with donepezil (n = 92), galantamine (n = 33), or rivastigmine (n = 46) were enrolled. Response to treatment was quantified by grading the patient's cognitive state (Mini-Mental State Examination) and the patient's ability to perform normal daily activities (Activities of Daily Living, Instrumental Activities of Daily Living) at baseline and after 6 and 12 months of treatment. Genetic variation was comprehensively characterized and analyzed at two loci: CYP2D6, which is involved in donepezil and galantamine metabolism, and BCHE, which codes for an enzyme (butyrylcholinesterase) which is both target and metabolizer of rivastigmine. APOE (coding for apolipoprotein E), which is associated with the risk of AD and inefficacy of specific AD treatments, was genotyped to control for patient stratification. The influence of the CYP2D6 and BCHE genotype on clinical changes after 12 months was evaluated by several tests of association.

Results: After 1 year of treatment, 29, 12, and 12 of the patients receiving donepezil, galantamine, and rivastigmine, respectively, showed a cognitive decrement, while eight patients interrupted the therapy before 12 months of treatment. No significant differences between the three treatments were observed in terms of response and tolerability. Non-responders show a higher proportion of BCHE and CYP2D6 mutated alleles, but genetic variation at the two loci was not a reliable predictor of clinical changes in AD patients treated with cholinesterase inhibitors.

Conclusions: Individualized therapy based on CYP2D6 and BCHE genotypes is unlikely to be beneficial for treating Alzheimer's disease patients in routine clinical practice.
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http://dx.doi.org/10.1007/s00228-011-1064-xDOI Listing
November 2011

Evolution of detoxifying systems: the role of environment and population history in shaping genetic diversity at human CYP2D6 locus.

Pharmacogenet Genomics 2010 Aug;20(8):485-99

Department of Biology and Evolution, University of Ferrara, Ferrara, Italy.

Objective: The transition from food collection to food production (FP) modified the nature of selective pressures, and several studies illustrate that genetic adaptation to new lifestyle has occurred in humans since the agricultural revolution. Here we test the hypothesis that high levels of genetic variation at CYP2D6, a locus coding for a detoxifying enzyme of the cytochrome P450 complex, reflect this change.

Methods: We compared DNA sequences and predicted the levels of enzyme activity across 10 African, Asian and European populations, six of which currently rely on hunting and gathering (HG) while four on food production (FP).

Results And Conclusion: HG and FP showed similar levels of CYP2D6 diversity, but displayed different substitution patterns at coding DNA sites possibly related to selective differences. Comparison with variation at presumably neutral independent loci confirmed this finding, despite the confounding effects of population history, resulting in higher overall variation in Africans than in Eurasians. The differences between HG and FP populations suggest that new lifestyle and dietary habits acquired in the transition to agriculture affected the variation pattern at CYP2D6, leading to an increase in FP populations of the frequency of alleles that are associated with a slower rate of metabolism. These alleles reached a balanced co-existence with other important and previously selected variants. We suggest that the pronounced substrate-dependent activity of most of these enzymes expanded the spectrum of the metabolic response.
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http://dx.doi.org/10.1097/FPC.0b013e32833bba25DOI Listing
August 2010

Pharmacogenetic variation at CYP2C9, CYP2C19, and CYP2D6 at global and microgeographic scales.

Pharmacogenet Genomics 2009 Feb;19(2):170-9

Department of Forensic Medicine, University of Helsinki, Helsinki, Finland.

Objectives: CYP2C9, CYP2C19, and CYP2D6 belong to a subfamily of cytochrome P450 (CYP) enzymes, associated mainly with the metabolism of exogenous compounds in the human body. The genes coding for these enzymes are highly polymorphic and thus of major pharmacogenetic importance. By systematically retrieving data from the literature and genotyping new population samples, we aimed at describing the worldwide distribution of genetic variation at these loci. We created a comprehensive resource of frequency data for the most important CYP2C9, CYP2C19, and CYP2D6 genetic variants in 129, 146, and 138 different population samples, respectively. Furthermore, we showed how demographic history can affect pharmacogenetic variation at a microgeographic scale by analyzing regional samples from Finland, which represents a well-known genetic isolate.

Methods: Data were obtained from the literature from 1991 to 2007 as well as by genotyping new population samples at four CYP2C9, two CYP2C19, and 12 CYP2D6 variable sites affecting enzymatic activity.

Results And Conclusion: Our study shows that: (i) altered activity variants of CYP2C9, CYP2C19, and CYP2D6 occur globally in all geographic regions, reaching extremely high frequencies in some populations; (ii) each of the CYP genes studied shows a distinct geographic pattern of variation; (iii) population substructure can strongly affect the variation seen in pharmacogenetic loci; and (iv) several geographic regions of pharmacogenetic interest are still poorly characterized.
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http://dx.doi.org/10.1097/FPC.0b013e32831ebb30DOI Listing
February 2009

Genetic variation in Northern Thailand Hill Tribes: origins and relationships with social structure and linguistic differences.

BMC Evol Biol 2007 Aug 16;7 Suppl 2:S12. Epub 2007 Aug 16.

Dipartimento di Biologia ed Evoluzione, Università di Ferrara, via L, Borsari 46, 44100 Ferrara, Italy.

Background: Ethnic minorities in Northern Thailand, often referred to as Hill Tribes, are considered an ideal model to study the different genetic impact of sex-specific migration rates expected in matrilocal (women remain in their natal villages after the marriage and men move to their wife's village) and patrilocal societies (the opposite is true). Previous studies identified such differences, but little is known about the possible interaction with another cultural factor that may potentially affect genetic diversity, i.e. linguistic differences. In addition, Hill Tribes started to migrate to Thailand in the last centuries from different Northern areas, but the history of these migrations, the level of genetic legacy with their places of origin, and the possible confounding effects related to this migration history in the patterns of genetic diversity, have not been analysed yet. Using both original and published data on the Hill Tribes and several other Asian populations, we focused on all these aspects.

Results: Genetic variation within population at mtDNA is lower in matrilocal, compared to patrilocal, tribes. The opposite is true for Y-chromosome microsatellites within the Sino-Tibetan linguistic family, but Hmong-Mien speaking patrilocal groups have a genetic diversity very similar to the matrilocal samples. Population divergence ranges between 5% and 14% at mtDNA sequences, and between 5% and 36% at Y-chromosomes STRs, and follows the sex-specific differences expected in patrilocal and matrilocal tribes. On the average, about 2 men and 14 women, and 4 men and 4 women, are exchanged in patrilocal and matrilocal tribes every generation, respectively. Most of the Hill Tribes in Thailand seem to preserve a genetic legacy with their likely geographic origin, with children adoption probably affecting this pattern in one tribe.

Conclusion: Overall, the sex specific genetic signature of different postmarital habits of residence in the Hill Tribes is robust. However, specific perturbations related to linguistic differences, population specific traits, and the complex migratory history of these groups, can be identified. Additional studies in different populations are needed, especially to obtain more precise estimates of the migration parameters.
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http://dx.doi.org/10.1186/1471-2148-7-S2-S12DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1963483PMC
August 2007

Tracing past human male movements in northern/eastern Africa and western Eurasia: new clues from Y-chromosomal haplogroups E-M78 and J-M12.

Mol Biol Evol 2007 Jun 10;24(6):1300-11. Epub 2007 Mar 10.

Dipartimento di Genetica e Biologia Molecolare, Sapienza Università di Roma, Rome, Italy, and Laboratoire d'Immunologie, Hôpital de Sainte-Marguerite, Marseille, France.

Detailed population data were obtained on the distribution of novel biallelic markers that finely dissect the human Y-chromosome haplogroup E-M78. Among 6,501 Y chromosomes sampled in 81 human populations worldwide, we found 517 E-M78 chromosomes and assigned them to 10 subhaplogroups. Eleven microsatellite loci were used to further evaluate subhaplogroup internal diversification. The geographic and quantitative analyses of haplogroup and microsatellite diversity is strongly suggestive of a northeastern African origin of E-M78, with a corridor for bidirectional migrations between northeastern and eastern Africa (at least 2 episodes between 23.9-17.3 ky and 18.0-5.9 ky ago), trans-Mediterranean migrations directly from northern Africa to Europe (mainly in the last 13.0 ky), and flow from northeastern Africa to western Asia between 20.0 and 6.8 ky ago. A single clade within E-M78 (E-V13) highlights a range expansion in the Bronze Age of southeastern Europe, which is also detected by haplogroup J-M12. Phylogeography pattern of molecular radiation and coalescence estimates for both haplogroups are similar and reveal that the genetic landscape of this region is, to a large extent, the consequence of a recent population growth in situ rather than the result of a mere flow of western Asian migrants in the early Neolithic. Our results not only provide a refinement of previous evolutionary hypotheses but also well-defined time frames for past human movements both in northern/eastern Africa and western Eurasia.
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http://dx.doi.org/10.1093/molbev/msm049DOI Listing
June 2007

CYP2D6 worldwide genetic variation shows high frequency of altered activity variants and no continental structure.

Pharmacogenet Genomics 2007 Feb;17(2):93-101

Department of Forensic Medicine, University of Helsinki, Finland.

Background And Objective: CYP2D6, a member of the cytochrome P450 superfamily, is responsible for the metabolism of about 25% of the commonly prescribed drugs. Its activity ranges from complete deficiency to excessive activity, potentially causing toxicity of medication or therapeutic failure with recommended drug dosages. This study aimed to describe the CYP2D6 diversity at the global level.

Methods: A total of 1060 individuals belonging to 52 worldwide-distributed populations were genotyped at 12 highly informative variable sites, as well as for gene deletion and duplications. Phenotypes were predicted on the basis of haplotype combinations.

Results And Conclusions: Our study shows that (i) CYP2D6 diversity is far greater within than between populations and groups thereof, (ii) null or low-activity variants occur at high frequencies in various areas of the world, (iii) linkage disequilibrium is lowest in Africa and highest in the Americas. Patterns of variation, within and among populations, are similar to those observed for other autosomal markers (e.g. microsatellites and protein polymorphisms), suggesting that the diversity observed at the CYP2D6 locus reflects the same factors affecting variation at random genome markers.
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http://dx.doi.org/10.1097/01.fpc.0000239974.69464.f2DOI Listing
February 2007

CYP2D6 genotyping by a multiplex primer extension reaction.

Clin Chem 2005 Jul 19;51(7):1291-5. Epub 2005 May 19.

Department of Forensic Medicine, University of Helsinki, Helsinki, Finland.

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http://dx.doi.org/10.1373/clinchem.2004.046466DOI Listing
July 2005

Molecular diversity at the CYP2D6 locus in the Mediterranean region.

Eur J Hum Genet 2004 Nov;12(11):916-24

Department of Biology, University of Ferrara, via Borsari 46, 44100 Ferrara, Italy.

Despite the importance of cytochrome P450 in the metabolism of many drugs, several aspects of molecular variation at one of the main loci coding for it, CYP2D6, have never been analysed so far. Here we show that it is possible to rapidly and efficiently genotype the main European allelic variants at this locus by a SNaPshot method identifying chromosomal rearrangements and nine single-nucleotide polymorphisms. Haplotypes could be reconstructed from data on 494 chromosomes in six populations of the Mediterranean region. High levels of linkage disequilibrium were found within the chromosome region screened, suggesting that CYP2D6 may be part of a genomic recombination block, and hence that, aside from unequal crossingover that led to large chromosomal rearrangements, its haplotype diversity essentially originated through the accumulation of mutations. With the only, albeit statistically insignificant, exception of Syria, haplotype frequencies do not differ among the populations studied, despite the presence among them of three well-known genetic outliers, which could be the result of common selective pressures playing a role in shaping CYP2D6 variation over the area of Europe that we surveyed.
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http://dx.doi.org/10.1038/sj.ejhg.5201243DOI Listing
November 2004

Mitochondrial DNA diversity in South America and the genetic history of Andean highlanders.

Mol Biol Evol 2003 Oct 27;20(10):1682-91. Epub 2003 Jun 27.

Area di Antropologia, Dipartimento di Biologia e. s., Università di Bologna, Bologna, Italy.

We analyzed mtDNA sequence variation in 590 individuals from 18 south Amerindian populations. The spatial pattern of mtDNA diversity in these populations fits well the model proposed on the basis of Y-chromosome data. We found evidence of a differential action of genetic drift and gene flow in western and eastern populations, which has led to genetic divergence in the latter but not in the former. Although it is not possible to identify a pattern of genetic variation common to all South America, when western and eastern populations are analyzed separately, the mtDNA diversity in both regions fits the isolation-by-distance model, suggesting independent evolutionary dynamics. Maximum-likelihood estimates of divergence times between central and south Amerindian populations fall between 13,000 and 19,000 years, which is consistent with a Pleistocenic peopling of South America. Moreover, comparison of among-population variability of mtDNA and Y-chromosome DNA seems to indicate that South America is the only continent where the levels of differentiation are similar for maternal and paternal lineages.
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http://dx.doi.org/10.1093/molbev/msg188DOI Listing
October 2003

Mitochondrial diversity in linguistic isolates of the Alps: a reappraisal.

Hum Biol 2002 Oct;74(5):725-30

Dipartimento di Biologia, Università di Ferrara, Ferrara, Italy.

In Stenico et al. (1996) we reported unusually high levels of mitochondrial diversity in the Alps. In particular, two communities of Ladin speakers appeared the most extreme European mitochondrial outliers at that time. Recently, it has been observed that some rare nucleotide substitutions occur repeatedly among those sequences, raising the possibility of systematic sequencing errors. No biological material was left from the previous study, and hence we had to sample new individuals from the same communities. Here, we present the HVSI sequence variation, along with haplogroup assignment based on restriction fragment length polymorphism (RFLP), in 20 Ladin speakers of Colle Santa Lucia. None of the new sequences displays substitutions at the sites viewed as problematic. However, Ladins still show high levels of mtDNA diversity, both within their community and with respect to other Europeans, and they can still be considered one of the main European mitochondrial outliers.
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http://dx.doi.org/10.1353/hub.2002.0060DOI Listing
October 2002
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