Genetic evidence suggests a sense of family, parity and conquest in the Xiongnu Iron Age nomads of Mongolia.

In an effort to characterize the people who composed the groups known as the Xiongnu, nuclear and whole mitochondrial DNA data were generated from the skeletal remains of 52 individuals excavated from the Tamir Ulaan Khoshuu (TUK) cemetery in Central Mongolia. This burial site, attributed to the Xiongnu period, was used from the first century BC to the first century AD. Kinship analyses were conducted using autosomal and Y-chromosomal DNA markers along with complete sequences of the mitochondrial genome. These analyses suggested close kin relationships between many individuals. Nineteen such individuals composed a large family spanning five generations. Within this family, we determined that a woman was of especially high status; this is a novel insight into the structure and hierarchy of societies from the Xiongnu period. Moreover, our findings confirmed that the Xiongnu had a strongly admixed mitochondrial and Y-chromosome gene pools and revealed a significant western component in the Xiongnu group studied. Using a fine-scale approach (haplotype instead of haplogroup-level information), we propose Scytho-Siberians as ancestors of the Xiongnu and Huns as their descendants.

The limitations of kinship determinations using STR data in ill-defined populations.

The likelihood ratio (LR) method is commonly used to determine kinship in civil, criminal, or forensic cases. For the past 15 years, our research group has also applied LR to ancient STR data and obtained kinship results for collections of graves or necropolises. Although we were able to reconstruct large genealogies, some pairs of individuals showed ambiguous results. Second-degree relationships, half-sibling pairs for example, were often inconsistent with detected first-degree relationships, such as parent/child or brother/sister pairs. We therefore set about providing empirical estimations of the error rates for the LR method in living populations with STR allelic diversities comparable to that of the ancient populations we had previously studied. We collected biological samples in the field in North-Eastern Siberia and West Africa and studied more than 800 pairs of STR profiles from individuals with known relationships. Because commercial STR panels were constructed for specific regions (namely Europe and North America), their allelic makeup showed a significant deficit in diversity when compared to European populations, replicating a situation often faced in ancient DNA studies. We assessed the capacity of the LR method to confirm known relationships (effectiveness) and its capacity to detect those relationships (reliability). Concerns over the effectiveness of LR determinations are mostly an issue in forensic studies, while the reliability of the detection of kinship is an issue for the study of necropolises or other large gatherings of unidentified individuals, such as disaster victims or mass graves. We show that the application of LR to both test populations highlights specific issues (both false positives and false negatives) that prevent the confirmation of second-degree kinship or even full siblingship in small populations. Up to 29% of detected full sibling relationships were either overestimated half-sibling relationships or underestimated parent-offspring relationships. The error rate for detected half-sibling relationships was even higher, reaching 41%. Only parent-offspring pairs were reliably detected or confirmed. This implies that, in populations that are small, ill-defined, or for which the STR loci analyzed are inappropriate, an examiner might not be able to distinguish a pair of full siblings from a pair of half-siblings. Furthermore, half-sibling pairs might be overlooked altogether, an issue that is exacerbated by the common confusion, in many languages and cultures, between half-siblings and full siblings. Consequently, in the study of ancient populations, human remains of unknown origins, or poorly surveyed modern populations, we recommend a conservative approach to kinship determined by LR. Next-generation sequencing data should be used when possible, but the costs and technology involved might be prohibitive. Therefore, in potentially contentious situations or cases lacking sufficient external information, uniparental markers should be analyzed: ideally, complete mitochondrial genomes and Y-chromosome haplotypes (STR, SNP, and/or sequencing).

Genetic kinship and admixture in Iron Age Scytho-Siberians.

Scythians are known from written sources as horse-riding nomadic peoples who dominated the Eurasian steppe throughout the Iron Age. However, their origins and the exact nature of their social organization remain debated. Three hypotheses prevail regarding their origins that can be summarized as a "western origin", an "eastern origin" and a "multi-regional origin". In this work, we first aimed to address the question of the familial and social organization of some Scythian groups (Scytho-Siberians) by testing genetic kinship and, second, to add new elements on their origins through phylogeographical analyses. Twenty-eight Scythian individuals from 5 archeological sites in the Tuva Republic (Russia) were analyzed using autosomal Short Tandem Repeats (STR), Y-STR and Y-SNP typing as well as whole mitochondrial (mtDNA) genome sequencing. Familial relationships were assessed using the Likelihood Ratio (LR) method. Thirteen of the 28 individuals tested were linked by first-degree relationships. When related, the individuals were buried together, except for one adult woman, buried separately from her mother and young sister. Y-chromosome analysis revealed a burial pattern linked to paternal lineages, with men bearing closely related Y-haplotypes buried on the same sites. Inversely, various mtDNA lineages can be found on each site. Y-chromosomal and mtDNA haplogroups were almost equally distributed between Western and Eastern Eurasian haplogroups. These results suggest that Siberian Scythians were organized in patrilocal and patrilineal societies with burial practices linked to both kinship and paternal lineages. It also appears that the group analyzed shared a greater genetic link with Asian populations than Western Scythians did.

New genetic evidence of affinities and discontinuities between bronze age Siberian populations.

OBJECTIVES: This work focuses on the populations of South Siberia during the Eneolithic and Bronze Age and specifically on the contribution of uniparental lineage and phenotypical data to the question of the genetic affinities and discontinuities between western and eastern populations. MATERIALS AND METHODS: We performed molecular analyses on the remains of 28 ancient humans (10 Afanasievo (3600-2500 BC) and 18 Okunevo (2500-1800 BC) individuals). For each sample, two uniparentally inherited systems (mitochondrial DNA and Y-chromosome DNA) were studied, in order to trace back maternal and paternal lineages. Phenotype-informative SNPs (Single Nucleotide Polymorphisms) were also analyzed, along with autosomal STRs (Short Tandem Repeats). RESULTS: Most of the Afanasievo men submitted to analysis belonged to a single sub-haplogroup, R1b1a1a, which reveals the predominance of this haplogroup in these early Bronze Age populations. Conversely, Okunevo individuals carried more diverse paternal lineages that mostly belonged to Asian/Siberian haplogroups. These differences are also apparent, although less strongly, in mitochondrial lineage composition and phenotype marker variant frequencies. DISCUSSION: This study provides new elements that contribute to our understanding of the genetic interactions between populations in Eneolithic and Bronze Age southern Siberia. Our results support the hypothesis of a genetic link between Afanasievo and Yamnaya (in western Eurasia), as suggested by previous studies of other markers. However, we found no Y-chromosome lineage evidence of a possible Afanasievo migration to the Tarim Basin. Moreover, the presence of Y-haplogroup Q in Okunevo individuals links them to Native American populations, as was suggested by whole-genome sequencing.

Virus and ancient DNA: back to the future.

Paleovirology, the study of ancient viruses, is a recent scientific development. It belongs to the domain of ancient DNA studies, paleogenetics. The analytical power of this discipline, that has many applications, is nevertheless limited by the poor conservation of DNA (and RNA) found in fossils and the subsequent methodological problems (amplification issues, post-mortem lesions, contaminations). These issues must be addressed in order to exploit the full potential of preserved nucleic acids within ancient remains. Once these difficulties have been overcome, it becomes possible to characterize ancient viruses and particular steps of their evolution or even adaptation to their hosts. Shedding light on key aspects of past epidemics allows for a better comprehension of present situations and for the anticipation of future situations where viral pathogens emerge or re-emerge. The examples described in this article illustrate these facts.

Genetic diversity of a late prehispanic group of the Quebrada de Humahuaca, northwestern Argentina.

This palaeogenetic study focused on the analysis of a late prehispanic Argentinean group from the Humahuaca valley, with the main aim of reconstructing its (micro)evolutionary history. The Humahuaca valley, a natural passageway from the eastern plains to the highlands, was the living environment of Andean societies whose cultural but especially biological diversity is still poorly understood. We analyzed the DNA extracted from 39 individuals who populated this upper valley during the Regional Development period (RDP) (between the 11th and 15th centuries CE), to determine their maternal and paternal genetic ancestry. Some mitochondrial and Y-chromosomal haplotypes specific to the Andean region are consistent with an origin in the highlands of Central Andes. On the other hand, a significant genetic affinity with contemporary admixed communities of the Chaco area was detected. Expectedly, recent demographic events, such as the expansion of the Inca Empire or the European colonization, have changed the original mitochondrial gene pool of the ancient Humahuaca Valley community. Finally, we identified a particular geographical organization of the prehispanic populations of Northwestern Argentina. Our results suggest that the communities of the region were divided between two different spheres of interaction, which is consistent with assumptions made by means of craniometric traits.

Ancestry of modern Europeans: contributions of ancient DNA.

Understanding the peopling history of Europe is crucial to comprehend the origins of modern populations. Of course, the analysis of current genetic data offers several explanations about human migration patterns which occurred on this continent, but it fails to explain precisely the impact of each demographic event. In this context, direct access to the DNA of ancient specimens allows the overcoming of recent demographic phenomena, which probably highly modified the constitution of the current European gene pool. In recent years, several DNA studies have been successfully conducted from ancient human remains thanks to the improvement of molecular techniques. They have brought new fundamental information on the peopling of Europe and allowed us to refine our understanding of European prehistory. In this review, we will detail all the ancient DNA studies performed to date on ancient European DNA from the Middle Paleolithic to the beginning of the protohistoric period.

Ancient DNA reveals male diffusion through the Neolithic Mediterranean route.

The Neolithic is a key period in the history of the European settlement. Although archaeological and present-day genetic data suggest several hypotheses regarding the human migration patterns at this period, validation of these hypotheses with the use of ancient genetic data has been limited. In this context, we studied DNA extracted from 53 individuals buried in a necropolis used by a French local community 5,000 y ago. The relatively good DNA preservation of the samples allowed us to obtain autosomal, Y-chromosomal, and/or mtDNA data for 29 of the 53 samples studied. From these datasets, we established close parental relationships within the necropolis and determined maternal and paternal lineages as well as the absence of an allele associated with lactase persistence, probably carried by Neolithic cultures of central Europe. Our study provides an integrative view of the genetic past in southern France at the end of the Neolithic period. Furthermore, the Y-haplotype lineages characterized and the study of their current repartition in European populations confirm a greater influence of the Mediterranean than the Central European route in the peopling of southern Europe during the Neolithic transition.

Ancient DNA suggests the leading role played by men in the Neolithic dissemination.

The impact of the Neolithic dispersal on the western European populations is subject to continuing debate. To trace and date genetic lineages potentially brought during this transition and so understand the origin of the gene pool of current populations, we studied DNA extracted from human remains excavated in a Spanish funeral cave dating from the beginning of the fifth millennium B.C. Thanks to a "multimarkers" approach based on the analysis of mitochondrial and nuclear DNA (autosomes and Y-chromosome), we obtained information on the early Neolithic funeral practices and on the biogeographical origin of the inhumed individuals. No close kinship was detected. Maternal haplogroups found are consistent with pre-Neolithic settlement, whereas the Y-chromosomal analyses permitted confirmation of the existence in Spain approximately 7,000 y ago of two haplogroups previously associated with the Neolithic transition: G2a and E1b1b1a1b. These results are highly consistent with those previously found in Neolithic individuals from French Late Neolithic individuals, indicating a surprising temporal genetic homogeneity in these groups. The high frequency of G2a in Neolithic samples in western Europe could suggest, furthermore, that the role of men during Neolithic dispersal could be greater than currently estimated.

Evaluation of whole-genome enrichment and sequencing of T. pallidum from FFPE samples after 75 years.

The recent developments in genomic sequencing have permitted the publication of many new complete genome sequences of Treponema pallidum pallidum, the bacterium responsible for syphilis, which has led to a new understanding of its phylogeny and diversity. However, few archived samples are available, because of the degradability of the bacterium and the difficulties in preservation. We present a complete genome obtained from a Formalin-Fixed Paraffin-Embedded (FFPE) organ sample from 1947, kept at the Strasbourg Faculty of Medicine. This is the preliminary, proof-of concept study of this collection/biobank of more than 1.5 million FFPE samples and the evaluation of the feasibility of genomic analyses. We demonstrate here that even degraded DNA from fragile bacteria can be recovered from 75-year-old FFPE samples and therefore propose that such collections as this one can function as sources of biological material for genetic studies of pathogens, cancer, or even the historical human population itself.

Recurrent familial case of early childhood sudden death: Complex post mortem genetic investigations.

INTRODUCTION: Sudden Unexplained Death in Childhood (SUDC) needs to be fully assessed considering its impact on the family, parents and siblings. Inborn Errors of Metabolism (IEM) such as Medium-Chain Acyl-CoA Dehydrogenase Deficiency (MCADD) should be taken into consideration when SUDC occurres. Our aim is to present a family with two successive SUDC and to discuss the post-mortem genetics investigations revealing an IEM implication. CASES REPORT: A complete autopsy with genetic testing was performed when the proband, a 4-year-old girl, died. A few years previously, her older brother had died at the same age and off the same condition. Years later, his exhumation was necessary in order to perform a post-mortem diagnosis.The two siblings were revealed to have had the same pathogenic genotype of the ACADM gene, heterozygous substitutions in ACADM (NM_000016.5): c.985 A>G p.(Lys329Glu) and c.347 G>A p.(Cys116Tyr). In addition, they also both carried a VUS in TECRL, a gene implicated in Catecholaminergic Polymorphic Tachycardia Ventricular (CPVT) and SUDC. CONCLUSION: We illustrate the importance of exome analyses for investigating unexplained sudden death, especially in children, with the possible impact for genetic counselling in the family. The finding of the implication of ACADM gene in this case, raises likely responsibility of the public health system in countries such as France, who delayed implementation of new born screening for these conditions. Exome analyses in this case detected unexpected complexity in interpretation linked to the identification of a second candidate gene for SUDC.

[DNA analysis in the anthropological approach of ancient populations]. / L'analyse ADN dans l'approche anthropologique des populations du passé

The authors highlight the opportunities to reconstruct the human Eurasian steppe migration movements with the analyses of nuclear DNA markers (short tandem repeats on autosomal DNA and on the Y chromosome) as well as mitochondrial DNA markers. They studied 26 ancient human samples from the Krasnoyarsk area (Southern Siberia). The specimens were dated from the middle of the second millennium BC to the fourth century AD. The Y chromosome and the mitochondrial analyses revealed that few of them seem to be related matrilineally or patrilineally, but all subjects belong to Y haplogroup R1a1a-M17 which is known as a marker of the eastward migration of the early Indo-Europeans. Their results are in accordance with the hypothesis that at the Bronze and Iron Ages south Siberia was settled predominantly by European subjects suggesting an eastward migration of kurgan people across the Russo-Kazakh steppe. The single nucleotide polymorphisms (SNP) analyses on the physical traits indicate that the ancient studied specimens were blue or green eyed, fair skinned and light-haired.

Detection of genetic variation in KCNQ1 gene by high-resolution melting analysis in a prospective-based series of postmortem negative sudden death: comparison of results obtained in fresh frozen and formalin-fixed paraffin-embedded tissues.

High-resolution melting (HRM) analysis is a recently developed molecular technique proved to be applicable for detection of genetic variation, notably in sudden cardiac death. In certain circumstances, especially in postmortem genetic investigations, the formalin-fixed and paraffin-embedded (FFPE) tissues are the only DNA source available. The present study aimed to develop HRM assays, optimized for the analysis of FFPE tissues, to detect sequence variations in KCNQ1 exons in a prospective population-based series of postmortem negative sudden death and to compare the results between the paired freshly frozen and FFPE tissue samples simultaneously obtained from the same case. The analyses were conducted in each case of sudden death involving cases younger than 35 years with no significant morphological anomalies particularly with no cardiac structural disease and with negatives toxicological investigations. HRM analysis was successfully optimized for 13 of the 16 exons of the KCNQ1 gene. All mutated samples were correctly identified by HRM whatever the type of tissue tested. However, for FFPE samples, HRM indicated more positive samples than classical sequencing, used in parallel, due to the degradation of DNA by formalin fixation. This is the first postmortem study of KCNQ1 mutation detection with HRM on DNA extracted from FFPE samples with adapted protocol. Despite the false-positive detection, we concluded that the use of HRM as a screening method with FFPE samples to analyze KCNQ1 mutations can reduce the number of sequencing reactions and, thus, results in substantial time and cost savings.

Splenic clearance of rigid erythrocytes as an inherited mechanism for splenomegaly and natural resistance to malaria.

BACKGROUND: In malaria-endemic areas, subjects from specific groups like Fulani have a peculiar protection against malaria, with high levels of IgM but also frequent anaemia and splenomegaly. The mechanisms underlying this phenotype remain elusive. METHODS: In a cohort study set up in Benin, West Africa, after a careful evaluation of malaria-related phenotypes, we measured the deformability of circulating erythrocytes in genetically distinct groups (including Fulani) living in sympatry, using ektacytometry and microsphiltration, a mimic of how the spleen clears rigid erythrocytes. Heritability of erythrocytes deformability was calculated, followed by a genome-wide association study (GWAS) of the same phenotype. FINDINGS: Compared to non-Fulani, Fulani displayed a higher deformability of circulating erythrocytes, pointing to an enhanced clearance of rigid erythrocytes by the spleen. This phenotype was observed in individuals displaying markers of Plasmodium falciparum infection. The heritability of this new trait was high, with a strong multigenic component. Five of the top 10 genes selected by a population structure-adjusted GWAS, expressed in the spleen, are potentially involved in splenic clearance of erythrocytes (CHERP, MB, PALLD, SPARC, PDE10A), through control of vascular tone, collagen synthesis and macrophage activity. INTERPRETATION: In specific ethnic groups, genetically-controlled processes likely enhance the innate retention of infected and uninfected erythrocytes in the spleen, explaining splenomegaly, anaemia, cryptic intrasplenic parasite loads, hyper-IgM, and partial protection against malaria. Beyond malaria-related phenotypes, inherited splenic hyper-filtration of erythrocytes may impact the pathogenesis of other hematologic diseases. FUNDING: ANR, National Geographic Society, IMEA, IRD, and Région Ile-de-France.

Application of the iPLEX™ Gold SNP genotyping method for the analysis of Amerindian ancient DNA samples: benefits for ancient population studies.

Important developments in the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) technique have generated new perspectives regarding SNP genotyping, which are particularly promising for ancient population-based studies. The main aim of the present study was to investigate the application of a MALDI-TOF MS-based SNP genotyping technique, called iPLEX(®) Gold, to analyze Amerindian ancient DNA samples. The first objective was to test the sensitivity of the method, which is recommended for DNA quantities between 10 and 5 ng, for ancient biological samples containing DNA molecules that were degraded and present in minute quantities. The second objective was to detail the advantages of this technique for studies on ancient populations. Two multiplexes were designed, allowing the major Amerindian mitochondrial and Y haplogroups to be determined simultaneously. This analysis has never been described before. Results demonstrated the reliability and accuracy of the method; data were obtained for both mitochondrial and nuclear DNA using picogram (pg) quantities of nucleic acid. This technique has the advantages of both MS and minisequencing techniques; thus, it should be included in the protocols for future ancient DNA studies.

Detection of age-related duplications in mtDNA from human muscles and bones.

Several studies have demonstrated the age-related accumulation of duplications in the D-loop of mitochondrial DNA (mtDNA) extracted from skeletal muscle. This kind of mutation had not yet been studied in bone. The detection of age-related mutations in bone tissue could help to estimate age at death within the context of legal medicine or/and anthropological identification procedures, when traditional osteological markers studied are absent or inefficient. As we detected an accumulation of a point mutation in mtDNA from an older individual's bones in a previous study, we tried here to identify if three reported duplications (150, 190, 260 bp) accumulate in this type of tissue. We developed a sensitive method which consists in the use of back-to-back primers during amplification followed by an electrophoresis capillary analysis. The aim of this study was to confirm that at least one duplication appears systematically in muscle tissue after the age of 20 and to evaluate the duplication age appearance in bones extracted from the same individuals. We found that the number of duplications increase from 38 years and that at least one duplicated fragment is present in 50% of cases after 70 years in this tissue. These results confirm that several age-related mutations can be detected in the D-loop of mtDNA and open the way for the use of molecular markers for age estimation in forensic and/or anthropological identification.

Human evolution in Siberia: from frozen bodies to ancient DNA.

BACKGROUND: The Yakuts contrast strikingly with other populations from Siberia due to their cattle- and horse-breeding economy as well as their Turkic language. On the basis of ethnological and linguistic criteria as well as population genetic studies, it has been assumed that they originated from South Siberian populations. However, many questions regarding the origins of this intriguing population still need to be clarified (e.g. the precise origin of paternal lineages and the admixture rate with indigenous populations). This study attempts to better understand the origins of the Yakuts by performing genetic analyses on 58 mummified frozen bodies dated from the 15th to the 19th century, excavated from Yakutia (Eastern Siberia). RESULTS: High quality data were obtained for the autosomal STRs, Y-chromosomal STRs and SNPs and mtDNA due to exceptional sample preservation. A comparison with the same markers on seven museum specimens excavated 3 to 15 years ago showed significant differences in DNA quantity and quality. Direct access to ancient genetic data from these molecular markers combined with the archaeological evidence, demographical studies and comparisons with 166 contemporary individuals from the same location as the frozen bodies helped us to clarify the microevolution of this intriguing population. CONCLUSION: We were able to trace the origins of the male lineages to a small group of horse-riders from the Cis-Baïkal area. Furthermore, mtDNA data showed that intermarriages between the first settlers with Evenks women led to the establishment of genetic characteristics during the 15th century that are still observed today.

Paleogenetical study of pre-Columbian samples from Pampa Grande (Salta, Argentina).

Ancient DNA recovered from 21 individuals excavated from burial sites in the Pampa Grande (PG) region (Salta province) of North-Western Argentina (NWA) was analyzed using various genetic markers (mitochondrial DNA, autosomal STRs, and Y chromosomal STRs). The results were compared to ancient and modern DNA from various populations in the Andean and North Argentinean regions, with the aim of establishing their relationships with PG. The mitochondrial haplogroup frequencies described (11% A, 47% B, and 42% D) presented values comparable to those found for the ancient Andean populations from Peru and San Pedro de Atacama. On the other hand, mitochondrial and Y chromosomal haplotypes were specific to PG, as they did not match any other of the South American populations studied. The described genetic diversity indicates homogeneity in the genetic structure of the ancient Andean populations, which was probably facilitated by the intense exchange network in the Andean zone, in particular among Tiwanaku, San Pedro de Atacama, and NWA. The discovery of haplotypes unique to PG could be due to a loss of genetic diversity caused by recent events affecting the autochthonous populations (establishment of the Inca Empire in the region, colonization by the Europeans).

Comparison between morphological and genetic data to estimate biological relationship: the case of the Egyin Gol necropolis (Mongolia).

Osseous and dental nonmetric (discrete) traits have long been used to assess population variability and affinity in anthropological and archaeological contexts. However, the full extent to which nonmetric traits can reliably be used as a proxy for genetic data when assessing close or familial relationships is currently poorly understood. This study represents the unique opportunity to directly compare genetic and nonmetric data for the same individuals excavated from the Egyin Gol necropolis, Mongolia. These data were analyzed to consider the general efficacy of nonmetric traits for detecting familial groupings in the absence of available genetic data. The results showed that the Egyin Gol population is quite homogenous both metrically and genetically confirming a previous suggestion that the same people occupied the necropolis throughout the five centuries of its existence. Kinship analysis detected the presence of potential family burials in the necropolis. Moreover, individuals buried in one sector of the necropolis were differentiated from other sectors on the basis of nonmetric data. This separation is likely due to an outside Turkish influence in the paternal line, as indicated by the results of Y-chromosome analysis. Affinity matrices based on nonmetric and genetic data were correlated demonstrating the potential of nonmetric traits for detecting relationships in the absence of genetic data. However, the strengths of the correlations were relatively low, cautioning against the use of nonmetric traits when the resolution of the familial relationships is low.