Expanding the forensic German mitochondrial DNA control region database: genetic diversity as a function of sample size and microgeography

Refining the Global Phylogeny of Mitochondrial N1a, X, and HV2 Haplogroups Based on Rare Mitogenomes from Croatian Isolates

Mitochondrial DNA (mtDNA) has been used for decades as a predominant tool in population genetics and as a valuable addition to forensic genetic research, owing to its unique maternal inheritance pattern that enables the tracing of individuals along the maternal lineage across numerous generations. The dynamic interplay between evolutionary forces, primarily genetic drift, bottlenecks, and the founder effect, can exert significant influence on genetic profiles. Consequently, the Adriatic islands have accumulated a subset of lineages that exhibits remarkable absence or rarity within other European populations. This distinctive genetic composition underscores the islands' potential as a significant resource in phylogenetic research, with implications reaching beyond regional boundaries to contribute to a global understanding. In the initial attempt to expand the mitochondrial forensic database of the Croatian population with haplotypes from small isolated communities, we sequenced mitogenomes of rare haplogroups from different Croatian island and mainland populations using next-generation sequencing (NGS). In the next step and based on the obtained results, we refined the global phylogeny of haplogroup N1a, HV2, and X by analyzing rare haplotypes, which are absent from the current phylogenetic tree. The trees were based on 16 novel and 52 previously published samples, revealing completely novel branches in the X and HV2 haplogroups and a new European cluster in the ancestral N1a variant, previously believed to be an exclusively African-Asian haplogroup. The research emphasizes the importance of investigating geographically isolated populations and their unique characteristics within a global context.

Evaluating population histories in Patagonia and Tierra del Fuego, Chile, using ancient mitochondrial and Y-chromosomal DNA

OBJECTIVES

This study aims to characterize the genetic histories of ancient hunter-gatherer groups in Fuego-Patagonia (Chile) with distinct Marine, Terrestrial, and Mixed Economy subsistence strategies. Mitochondrial (mtDNA) and Y-chromosome data were generated to test three hypotheses. H₀: All individuals were drawn from the same panmictic population; H₁: Terrestrial groups first populated the region and gave rise to highly specialized Marine groups by ~7,500 cal BP; or H₂: Marine and Terrestrial groups represent distinct ancestral lineages who migrated independently into the region.

METHODS

Ancient DNA was extracted from the teeth of 50 Fuegian-Patagonian individuals dating from 6,895 cal BP to after European arrival, and analyzed alongside other individuals from previous studies. Individuals were assigned to Marine, Terrestrial, and Mixed Economy groups based on archeological context and stable isotope diet inferences, and mtDNA (HVR1/2) and Y-chromosome variation was analyzed.

RESULTS

Endogenous aDNA was obtained from 49/50 (98%) individuals. Haplotype diversities, F_ST comparisons, and exact tests of population differentiation showed that Marine groups were significantly different from Terrestrial groups based on mtDNA (p < 0.05). No statistically significant differences were found between Terrestrial and Mixed Economy groups. Demographic simulations support models in which Marine groups diverged from the others by ~14,000 cal BP. Y-chromosome results showed similar patterns but were not statistically significant due to small sample sizes and allelic dropout.

DISCUSSION

These results support the hypothesis that Marine and Terrestrial economic groups represent distinct ancestral lineages who diverged during the time populations were expanding in the Americas, and may represent independent migrations into Fuego-Patagonia.

Population genetic structure of traditional populations in the Peruvian Central Andes and implications for South American population history

Molecular-based characterizations of Andean peoples are traditionally conducted in the service of elucidating continent-level evolutionary processes in South America. Consequently, genetic variation among "western" Andean populations is often represented in relation to variation among "eastern" Amazon and Orinoco River Basin populations. This west-east contrast in patterns of population genetic variation is typically attributed to large-scale phenomena, such as dual founder colonization events or differing long-term microevolutionary histories. However, alternative explanations that consider the nature and causes of population genetic diversity within the Andean region remain underexplored. Here we examine population genetic diversity in the Peruvian Central Andes using data from the mtDNA first hypervariable region and Y-chromosome short tandem repeats among 17 newly sampled populations and 15 published samples. Using this geographically comprehensive data set, we first reassessed the currently accepted pattern of western versus eastern population genetic structure, which our results ultimately reject: mtDNA population diversities were lower, rather than higher, within Andean versus eastern populations, and only highland Y-chromosomes exhibited significantly higher within-population diversities compared with eastern groups. Multiple populations, including several highland samples, exhibited low genetic diversities for both genetic systems. Second, we explored whether the implementation of Inca state and Spanish colonial policies starting at about ad 1400 could have substantially restructured population genetic variation and consequently constitute a primary explanation for the extant pattern of population diversity in the Peruvian Central Andes. Our results suggest that Peruvian Central Andean population structure cannot be parsimoniously explained as the sole outcome of combined Inca and Spanish policies on the region's population demography: highland populations differed from coastal and lowland populations in mtDNA genetic structure only; highland groups also showed strong evidence of female-biased gene flow and/or effective sizes relative to other Peruvian ecozones. Taken together, these findings indicate that population genetic structure in the Peruvian Central Andes is considerably more complex than previously reported and that characterizations of and explanations for genetic variation may be best pursued within more localized regions and defined time periods.

Mitochondrial DNA variation in the Viking age population of Norway

The medieval Norsemen or Vikings had an important biological and cultural impact on many parts of Europe through raids, colonization and trade, from about AD 793 to 1066. To help understand the genetic affinities of the ancient Norsemen, and their genetic contribution to the gene pool of other Europeans, we analysed DNA markers in Late Iron Age skeletal remains from Norway. DNA was extracted from 80 individuals, and mitochondrial DNA polymorphisms were detected by next-generation sequencing. The sequences of 45 ancient Norwegians were verified as genuine through the identification of damage patterns characteristic of ancient DNA. The ancient Norwegians were genetically similar to previously analysed ancient Icelanders, and to present-day Shetland and Orkney Islanders, Norwegians, Swedes, Scots, English, German and French. The Viking Age population had higher frequencies of K*, U*, V* and I* haplogroups than their modern counterparts, but a lower proportion of T* and H* haplogroups. Three individuals carried haplotypes that are rare in Norway today (U5b1b1, Hg A* and an uncommon variant of H*). Our combined analyses indicate that Norse women were important agents in the overseas expansion and settlement of the Vikings, and that women from the Orkneys and Western Isles contributed to the colonization of Iceland.

Ancient DNA from the Schild site in Illinois: Implications for the Mississippian transition in the Lower Illinois River Valley

Archaeologists have long debated whether rapid cultural change in the archaeological record is due to in situ developments, migration of a new group into the region, or the spread of new cultural practices into an area through existing social networks, with the local peoples adopting and adapting practices from elsewhere as they see fit (acculturation). Researchers have suggested each of these explanations for the major cultural transition that occurred at the beginning of the Mississippian period (AD 1050) across eastern North America. In this study, we used ancient DNA to test competing hypotheses of migration and acculturation for the culture change that occurred between the Late Woodland (AD 400-1050) and Mississippian (AD 1050-1500) periods in the Lower Illinois River Valley. We obtained sequences of the first hypervariable segment of the mitochondrial genome (mtDNA) from 39 individuals (17 Late Woodland, 22 Mississippian) interred in the Schild cemetery in western Illinois, and compared these lineages to ancient mtDNA lineages present at other sites in the region. Computer simulations were used to test a null hypothesis of population continuity from Late Woodland to Mississippian times at the Schild site and to investigate the possibility of gene flow from elsewhere in the region. Our results suggest that the Late Woodland to Mississippian cultural transition at Schild was not due to an influx of people from elsewhere. Instead, it is more likely that the transition to Mississippian cultural practices at this site was due to a process of acculturation.

Acceptance of domestic cat mitochondrial DNA in a criminal proceeding

Shed hair from domestic animals readily adheres to clothing and other contact items, providing a source of transfer evidence for criminal investigations. Mitochondrial DNA is often the only option for DNA analysis of shed hair. Human mitochondrial DNA analysis has been accepted in the US court system since 1996. The murder trial of the State of Missouri versus Henry L. Polk, Jr. represents the first legal proceeding where cat mitochondrial DNA analysis was introduced into evidence. The mitochondrial DNA evidence was initially considered inadmissible due to concerns about the cat dataset and the scientific acceptance of the marker. Those concerns were subsequently addressed, and the evidence was deemed admissible. This report reviews the case in regards to the cat biological evidence and its ultimate admission as generally accepted and reliable. Expansion and saturation analysis of the cat mitochondrial DNA control region dataset supported the initial interpretation of the evidence.

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.

Mitochondrial genome sequencing in Mesolithic North East Europe Unearths a new sub-clade within the broadly distributed human haplogroup C1

The human mitochondrial haplogroup C1 has a broad global distribution but is extremely rare in Europe today. Recent ancient DNA evidence has demonstrated its presence in European Mesolithic individuals. Three individuals from the 7,500 year old Mesolithic site of Yuzhnyy Oleni Ostrov, Western Russia, could be assigned to haplogroup C1 based on mitochondrial hypervariable region I sequences. However, hypervariable region I data alone could not provide enough resolution to establish the phylogenetic relationship of these Mesolithic haplotypes with haplogroup C1 mitochondrial DNA sequences found today in populations of Europe, Asia and the Americas. In order to obtain high-resolution data and shed light on the origin of this European Mesolithic C1 haplotype, we target-enriched and sequenced the complete mitochondrial genome of one Yuzhnyy Oleni Ostrov C1 individual. The updated phylogeny of C1 haplogroups indicated that the Yuzhnyy Oleni Ostrov haplotype represents a new distinct clade, provisionally coined “C1f”. We show that all three C1 carriers of Yuzhnyy Oleni Ostrov belong to this clade. No haplotype closely related to the C1f sequence could be found in the large current database of ancient and present-day mitochondrial genomes. Hence, we have discovered past human mitochondrial diversity that has not been observed in modern-day populations so far. The lack of positive matches in modern populations may be explained by under-sampling of rare modern C1 carriers or by demographic processes, population extinction or replacement, that may have impacted on populations of Northeast Europe since prehistoric times.

Mitochondrial variation among the Aymara and the signatures of population expansion in the central Andes

OBJECTIVES

The exploitation of marine resources and intensive agriculture led to a marked population increase early in central Andean prehistory. Constant historic and prehistoric population movements also characterize this region. These features undoubtedly affected regional genetic variation, but the exact nature of these effects remains uncertain.

METHODS

Mitochondrial DNA (mtDNA) hypervariable region I sequence variation in 61 Aymara individuals from La Paz, Bolivia, was analyzed and compared to sequences from 47 other South American populations to test hypotheses of whether increased female effective population size and gene flow influenced the mtDNA variation among central Andean populations.

RESULTS

The Aymara and Quechua were genetically diverse showing evidence of population expansion and large effective population size, and a demographic expansion model fits the mtDNA variation found among central Andean populations well. Estimated migration rates and the results of AMOVA and multidimensional scaling analysis suggest that female gene flow was also an important factor, influencing genetic variation among the central Andeans as well as lowland populations from western South America. mtDNA variation in south central Andes correlated better with geographic proximity than with language, and fit a population continuity model.

CONCLUSION

The mtDNA data suggests that the central Andeans experienced population expansion, most likely because of rapid demographic expansion after introduction of intensive agriculture, but roles of female gene flow need to be further explored.

Mitochondrial DNA diversity in two ethnic groups in southeastern Kenya: perspectives from the northeastern periphery of the Bantu expansion

The Bantu languages are widely distributed throughout sub-Saharan Africa. Genetic research supports linguists and historians who argue that migration played an important role in the spread of this language family, but the genetic data also indicates a more complex process involving substantial gene flow with resident populations. In order to understand the Bantu expansion process in east Africa, mtDNA hypervariable region I variation in 352 individuals from the Taita and Mijikenda ethnic groups was analyzed, and we evaluated the interactions that took place between the Bantu- and non-Bantu-speaking populations in east Africa. The Taita and Mijikenda are Bantu-speaking agropastoralists from southeastern Kenya, at least some of whose ancestors probably migrated into the area as part of Bantu migrations that began around 3,000 BCE. Our analyses indicate that they show some distinctive differences that reflect their unique cultural histories. The Taita are genetically more diverse than the Mijikenda with larger estimates of genetic diversity. The Taita cluster with other east African groups, having high frequencies of haplogroups from that region, while the Mijikenda have high frequencies of central African haplogroups and cluster more closely with central African Bantu-speaking groups. The non-Bantu speakers who lived in southeastern Kenya before Bantu speaking groups arrived were at least partially incorporated into what are now Bantu-speaking Taita groups. In contrast, gene flow from non-Bantu speakers into the Mijikenda was more limited. These results suggest a more complex demographic history where the nature of Bantu and non-Bantu interactions varied throughout the area.

Y-STR diversity and sex-biased gene flow among Caribbean populations

In the present study, we report, for the first time, the allele and haplotype frequencies of 17 Y-STR (Y-filer) loci in the populations of Haiti, Jamaica and the Bahamas (Abaco, Eleuthera, Exuma, Grand Bahama, Long Island and New Providence). This investigation was undertaken to assess the paternal genetic structure of the abovementioned Caribbean islands. A total of 607 different haplotypes were identified among the 691 males examined, of which 537 (88.5%) were unique. Haplotype diversities (HD) ranged from 0.989 in Long Island to 1.000 in Grand Bahama, with limited haplotype sharing observed among these Caribbean collections. Discriminatory capacity (DC) values were also high, ranging from 79.1% to 100% in Long Island and Grand Bahama, respectively, illustrating the capacity of this set of markers to differentiate between patrilineal related individuals within each population. Phylogenetic comparison of the Bahamian, Haitian and Jamaican groups with available African, European, East Asian and Native American populations reveals strong genetic ties with the continental African collections, a finding that corroborates our earlier work using autosomal STR and Y-chromosome binary markers. In addition, various degrees of sex-biased gene flow exhibiting disproportionately higher European paternal (as compared to autosomal) influences were detected in all Caribbean islands genotyped except for Abaco and Eleuthera. We attribute the presence or absence of asymmetric gene flow to unique, island specific demographic events and family structures.

Ancient DNA reveals kinship burial patterns of a pre-Columbian Andean community

BACKGROUND

A detailed genetic study of the pre-Columbian population inhabiting the Tompullo 2 archaeological site (department Arequipa, Peru) was undertaken to resolve the kin relationships between individuals buried in six different chullpas. Kin relationships were an important factor shaping the social organization in the pre-Columbian Andean communities, centering on the ayllu, a group of relatives that shared a common land and responsibilities. The aim of this study was to evaluate whether this Andean model of a social organization had an influence on mortuary practices, in particular to determine whether chullpas served as family graves.

RESULTS

The remains of forty-one individuals were analyzed with both uniparental (mtDNA, Y-chromosome) and biparental (autosomal microsatellites) markers. Reproducible HVRI sequences, autosomal and Y chromosomal STR profiles were obtained for 24, 16 and 11 individuals, respectively. Mitochondrial DNA diversity was comparable to that of ancient and contemporary Andean populations. The Tompullo 2 population exhibited the closest relationship with the modern population from the same region. A kinship analysis revealed complex pattern of relations within and between the graves. However mean relatedness coefficients regarding the pairs of individuals buried in the same grave were significantly higher than those regarding pairs buried in different graves. The Y chromosome profiles of 11 males suggest that only members of one male line were buried in the same grave.

CONCLUSIONS

Genetic investigation of the population that inhabited Tompullo 2 site shows continuity between pre-Columbian and modern Native Amerindian populations inhabiting the Arequipa region. This suggests that no major demographic processes have influenced the mitochondrial DNA diversity of these populations during the past five hundred years. The kinship analysis involving uni- and biparental markers suggests that the community that inhabited the Tompullo 2 site was organized into extended family groups that were buried in different graves. This finding is in congruence with known models of social organization of Andean communities.

Y-chromosomal microsatellite diversity in three culturally defined regions of historical Tibet

In the present study, we analyzed 17 Y-STR loci in 350 Tibetan males from three culturally defined regions of historical Tibet: Amdo (88), Kham (109) and U-Tsang (153). A total of 299 haplotypes were observed, 272 (90.9%) of which were unique. Only one Y-STR profile is shared across the three Tibetan groups and, incidentally, is also the most frequent haplotype (4.0%), represented by two, five and seven individuals from U-Tsang, Kham and Amdo, respectively. The overall haplotype diversity for the three Tibetan populations at 17 Y-STR loci was 0.9978 and the corresponding values for the extended (11-loci) and minimal (9-loci) haplotypes were 0.9935 and 0.9909, respectively. Both neighbor-joining and Rst pairwise analyses suggest a close genetic relationship between the Amdo and Kham populations, while U-Tsang is genetically distinct from the aforementioned groups. The results demonstrate that the 17 Y-STR loci analyzed are highly polymorphic in all three Tibetan populations examined and hence useful for forensic cases, paternity testing and population genetic studies.

Mitochondrial DNA variation in an isolated area of Central Italy

BACKGROUND

The genetic variation in Italy is the result of ancient population movement, demographic change, and geography. The increasing possibility of studying the maternal genetic structure of selected Italian population samples at a high level of phylogenetic resolution provides a particularly useful model to assess the presence of genetic traces of the ancient people who lived in Italy in pre-Roman times in present populations

AIM

In this study we reconstructed the genetic maternal history of Jenne and Vallepietra, two mountain communities in the Aniene Valley in the Simbruini Mountains near Rome. Both communities have been spared external invasion due to their geographic location, which very likely preserved the genetic pool of these autochthonous populations.

SUBJECTS AND METHODS

The study population (124 individuals from Jenne and Vallepietra) were investigated for D-loop mtDNA hypervariable segments I (HVS-I) and II (HVS-II) and for informative single nucleotide polymorphisms (SNPs) within the coding region. The detected haplotypes were then compared with those of other Italian, European and Mediterranean populations.

RESULTS

The distribution of mtDNA diversity in Jenne and Vallepietra, although similar to that found in other European populations, shows a basic variability and the typical signs of a certain degree of isolation between them and other populations analysed; in particular, the Vallepietra sample showed an unusually high frequency (71.3%) of mtDNA haplogroups which are typical of Near Eastern and South-Western Asian populations.

CONCLUSION

The high degree of differentiation between the two villages is intriguing, since it suggests a low level of gene flow between them, despite their close geographic proximity and shared linguistic features. The degree of their genetic isolation, also in comparison to other Italian, European and Mediterranean populations, is consistent with isolation among geographically separated populations.

Y-STR diversity in the Himalayas

Linguistic and ethnic diversity throughout the Himalayas suggests that this mountain range played an important role in shaping the genetic landscapes of the region. Previous Y-chromosome work revealed that the Himalayas acted as a biased bidirectional barrier to gene flow across the cordillera. In the present study, 17 Y-chromosomal short tandem repeat (Y-STR) loci included in the AmpFlSTR® Yfiler kit were analyzed in 344 unrelated males from three Nepalese populations (Tamang, Newar, and Kathmandu) and a general collection from Tibet. The latter displays the highest haplotype diversity (0.9990) followed by Kathmandu (0.9977), Newar (0.9570), and Tamang (0.9545). The overall haplotype diversity for the Himalayan populations at 17 Y-STR loci was 0.9973, and the corresponding values for the extended (11 loci) and minimal (nine loci) haplotypes were 0.9955 and 0.9942, respectively. No Y-STR profiles are shared across the four Himalayan collections at the 17-, 11-, and nine-locus resolutions considered, indicating a lack of recent gene flow among them. Phylogenetic analyses support our previous findings that Kathmandu, and to some extent Newar, received significant genetic influence from India while Tamang and Tibet exhibit limited or no gene flow from the subcontinent. A median-joining network of haplogroup O3a3c-M134 based on 15 Y-STR loci from our four Himalayan populations suggests either a male founder effect in Tamang, possibly from Tibet, or a recent bottleneck following their arrival south of the Himalayas from Tibet leading to their highly reduced Y single-nucleotide polymorphism and Y-STR diversity. The genetic uniqueness of the four Himalayan populations examined in this study merits the creation of separate databases for individual identification, parentage analysis, and population genetic studies.

Estimating haplotype frequency and coverage of databases

A variety of forensic, population, and disease studies are based on haploid DNA (e.g. mitochondrial DNA or Y-chromosome data). For any set of genetic markers databases of conventional size will normally contain only a fraction of all haplotypes. For several applications, reliable estimates of haplotype frequencies, the total number of haplotypes and coverage of the database (the probability that the next random haplotype is contained in the database) will be useful. We propose different approaches to the problem based on classical methods as well as new applications of Principal Component Analysis (PCA). We also discuss previous proposals based on saturation curves. Several conclusions can be inferred from simulated and real data. First, classical estimates of the fraction of unseen haplotypes can be seriously biased. Second, there is no obvious way to decide on required sample size based on traditional approaches. Methods based on testing of hypotheses or length of confidence intervals may appear artificial since no single test or parameter stands out as particularly relevant. Rather the coverage may be more relevant since it indicates the percentage of different haplotypes that are contained in a database; if the coverage is low, there is a considerable chance that the next haplotype to be observed does not appear in the database and this indicates that the database needs to be expanded. Finally, freeware and example data sets accompany the methods discussed in this paper: http://folk.uio.no/thoree/nhap/.

Mitochondrial DNA haplogroup diversity in Basques: a reassessment based on HVI and HVII polymorphisms

This study provides a more complete characterization of the mitochondrial genome variability of the Basques, including data on the hypervariable segment HVII of the D-loop region, which remains relatively unknown. To that end, genomic DNA from 55 healthy men living in the Arratia Valley (Biscay province) and the Goiherri region (Guipúzcoa province) was examined by direct sequencing. Three-generation pedigree charts were compiled to ensure the collection from autochthonous individuals. The most notable findings emerging from the analysis of haplogroup composition are: (i) lack of U8a mitochondrial lineage, a rare subhaplogroup recently identified in Basques and proposed as a Paleolithic marker, (ii) low frequency of haplogroup V, which conflicts with results of earlier analyses describing high frequencies in southwestern Europe, and (iii) high frequency of haplogroup J, especially subhaplogroups J1c1 and J2a. The frequency of haplogroup J does not coincide with previous mtDNA studies in present-day Basques, but is congruent with frequencies found in prehistoric and historic Basque populations. In explaining divergence in haplogroup composition between modern Basque samples, we hypothesized spatial heterogeneity promoted by population fragmentation due to extreme limitation of dispersal opportunities during the Pleistocene glaciations. Similarities between extinct and extant Basque populations as for the high frequency of lineage J, as well as the abundance of this haplogroup in northern Spain endorse a shift in the focus of attention of mtDNA analysts. A refined dissection of haplogroup J might provide more solid evidence about the process of postglacial recolonization of Europe, and thus about the shaping of the European gene pool.

A database of mitochondrial DNA hypervariable regions I and II sequences of individuals from Slovakia

In order to identify polymorphic positions and to determine their frequencies and the frequency of haplotypes in the human mitochondrial control region, two hypervariable regions (HV1 and HV2) of the mitochondrial DNA (mtDNA) of 374 unrelated individuals from Slovakia were amplified and sequenced. Sequence comparison led to the identification of 284 mitochondrial lineages as defined by 163 variable sites. Genetic diversity (GD) was estimated at 0.997 and the probability of two randomly selected individuals from population having identical mtDNA types (random match probability, RMP) for the both regions is 0.60%.

Redefinition of hypervariable region I in mitochondrial DNA control region and comparing its diversity among various ethnic groups

The hypervariable region I (HVR-I) of the mitochondrial DNA control region described in the literature is variable in its 5'and 3' ends as well as in its length, causing a problem when data from different ethnic groups are to be compared. To redefine HVR-I, which should be highly polymorphic yet relatively short in length, we analyzed 1437 reported sequences distributed among 11 geographic areas in the world. The results showed that the 237-bp (nts 16126-16362) redefined HVR-I (rHVR-I) had a global genetic diversity of 0.9905 and the 154-bp (nts 16209-16362) short HVR-I (sHVR-I) had a global diversity of 0.9735. Being flanked by a stretch of highly conservative sequences, both rHVR-I and sHVR-I can be produced by PCR, even if extracted from badly degraded specimens. Comparing the genetic diversity among 3870 sequences from 25 countries, we found that the genetic diversity of rHVR-I was 0.9869+/-0.0133 in Asian countries, 0.9685+/-0.0193 in African countries, 0.9299+/-0.0664 in European countries, and 0.8477+/-0.1857 in American countries, whereas that of sHVR-I was 0.9689+/-0.0284 in Asian countries, 0.9504+/-0.0334 in African countries, 0.8721+/-0.0911 in European countries, and 0.8230+/-0.1693 in American countries. The difference in genetic diversity among these countries is consistent with the notion that genetic diversity roughly reflects the genetic history of a given ethnic group. Our results indicate that a polymorphic, short, and PCR-producible HVR-I can be defined, making the comparison among various ethnic groups possible.

Comparison of maternal lineage and biogeographic analyses of ancient and modern Hungarian populations

The Hungarian language belongs to the Finno-Ugric branch of the Uralic family, but Hungarian speakers have been living in Central Europe for more than 1000 years, surrounded by speakers of unrelated Indo-European languages. In order to study the continuity in maternal lineage between ancient and modern Hungarian populations, polymorphisms in the HVSI and protein coding regions of mitochondrial DNA sequences of 27 ancient samples (10th-11th centuries), 101 modern Hungarian, and 76 modern Hungarian-speaking Sekler samples from Transylvania were analyzed. The data were compared with sequences derived from 57 European and Asian populations, including Finno-Ugric populations, and statistical analyses were performed to investigate their genetic relationships. Only 2 of 27 ancient Hungarian samples are unambiguously Asian: the rest belong to one of the western Eurasian haplogroups, but some Asian affinities, and the genetic effect of populations who came into contact with ancient Hungarians during their migrations are seen. Strong differences appear when the ancient Hungarian samples are analyzed according to apparent social status, as judged by grave goods. Commoners show a predominance of mtDNA haplotypes and haplogroups (H, R, T), common in west Eurasia, while high-status individuals, presumably conquering Hungarians, show a more heterogeneous haplogroup distribution, with haplogroups (N1a, X) which are present at very low frequencies in modern worldwide populations and are absent in recent Hungarian and Sekler populations. Modern Hungarian-speaking populations seem to be specifically European. Our findings demonstrate that significant genetic differences exist between the ancient and recent Hungarian-speaking populations, and no genetic continuity is seen.

Biological relationship between Central and South American Chibchan speaking populations: evidence from mtDNA

We examined mitochondrial DNA (mtDNA) haplogroup and haplotype diversity in 188 individuals from three Chibchan (Kogi, Arsario, and Ijka) populations and one Arawak (Wayuú) group from northeast Colombia to determine the biological relationship between lower Central American and northern South American Chibchan speakers. mtDNA haplogroups were obtained for all individuals and mtDNA HVS-I sequence data were obtained for 110 samples. Resulting sequence data were compared to 16 other Caribbean, South, and Central American populations using diversity measures, neutrality test statistics, sudden and spatial mismatch models, intermatch distributions, phylogenetic networks, and a multidimensional scaling plot. Our results demonstrate the existence of a shared maternal genetic structure between Central American Chibchan, Mayan populations and northern South American Chibchan-speakers. Additionally, these results suggest an expansion of Chibchan-speakers into South America associated with a shift in subsistence strategies because of changing ecological conditions that occurred in the region between 10,000-14,000 years before present.

Sequence analysis of mitochondrial DNA hypervariable regions: an approach to personal identification

BACKGROUND

Mitochondrial DNA (mtDNA) sequence analysis of the hypervariable control region has been shown to be an effective tool for personal identification. The high copy and maternal mode of inheritance make mtDNA analysis particularly useful when old samples or degradation of biological samples prohibits the detection of nuclear DNA analysis.

METHODS

This study reports mtDNA polymorphisms in both HV1 and HV2 of the non-coding D-loop region from 30 Iranian persons (10 unrelated families in three sequential maternal generations).

RESULTS

Eighty one polymorphic nucleotide positions were found, 32 in HV1 and 49 in HV2. The sequence of HV1 and HV2 and the occurred polymorphism were completely similar in each family, except for heteroplasmy in five positions in HV2. The average numbers of nucleotide differences between families were 5.2 nucleotides in HV1 and 2.8 nucleotides in HV2.

CONCLUSIONS

We expect eight nucleotide differences in sequence of both HV1 and HV2 in two unknown, unrelated Iranian samples.

Mitochondrial DNA variation of modern Tuscans supports the near eastern origin of Etruscans

The origin of the Etruscan people has been a source of major controversy for the past 2,500 years, and several hypotheses have been proposed to explain their language and sophisticated culture, including an Aegean/Anatolian origin. To address this issue, we analyzed the mitochondrial DNA (mtDNA) of 322 subjects from three well-defined areas of Tuscany and compared their sequence variation with that of 55 western Eurasian populations. Interpopulation comparisons reveal that the modern population of Murlo, a small town of Etruscan origin, is characterized by an unusually high frequency (17.5%) of Near Eastern mtDNA haplogroups. Each of these haplogroups is represented by different haplotypes, thus dismissing the possibility that the genetic allocation of the Murlo people is due to drift. Other Tuscan populations do not show the same striking feature; however, overall, ~5% of mtDNA haplotypes in Tuscany are shared exclusively between Tuscans and Near Easterners and occupy terminal positions in the phylogeny. These findings support a direct and rather recent genetic input from the Near East--a scenario in agreement with the Lydian origin of Etruscans. Such a genetic contribution has been extensively diluted by admixture, but it appears that there are still locations in Tuscany, such as Murlo, where traces of its arrival are easily detectable.

Liquid chromatography-electrospray ionization mass spectrometry for simultaneous detection of mtDNA length and nucleotide polymorphisms

We demonstrate the applicability of ion-pair reversed-phase high-performance liquid chromatography-electrospray ionization time-of-flight mass spectrometry (ICEMS) for the simultaneous characterization of length and nucleotide polymorphisms. Two sections within the first (HVS-I) and second (HVS-II) hypervariable segments of the mitochondrial (mt)DNA control region were selected as targets, both containing poly-cytosine (C) tracts, which display length heteroplasmy at a substantial frequency in the population. The two mtDNA sections were simultaneously amplified and analyzed by ICEMS in 90 maternally unrelated mother-offspring pairs from Austria. The findings were confirmed by direct sequencing of the polymerase chain reaction products. For the detailed characterization of present-length heteroplasmic variants, the results retrieved through ICEMS were more informative compared with those derived from direct sequencing. Hence, ICEMS represents an interesting option for successful application in forensic science.

Mitochondrial DNA Portrait of Latvians: Towards the Understanding of the Genetic Structure of Baltic-Speaking Populations

Mitochondrial DNA (mtDNA) variation was investigated in a sample of 299 Latvians, a Baltic-speaking population from Eastern Europe. Sequencing of the first hypervariable segment (HVS-I) in combination with analysis of informative coding region markers revealed that the vast majority of observed mtDNAs belong to haplogroups (hgs) common to most European populations. Analysis of the spatial distribution of mtDNA haplotypes found in Latvians, as well as in Baltic-speaking populations in general, revealed that they share haplotypes with all neighbouring populations irrespective of their linguistic affiliation. Hence, the results of our mtDNA analysis show that the previously described sharp difference between the Y-chromosomal hg N3 distribution in the paternally inherited gene pool of Baltic-speaking populations and of other European Indo-European speakers does not have a corresponding maternal counterpart.

Sequence polymorphisms of the mtDNA control region in a human isolate: the Georgians from Swanetia

In this work, we analyzed the sequence diversity of the mtDNA control region (HVI and HVII) in a sample of 48 individuals from Swanetia (Georgia), using direct fluorescent-based sequencing methods. We identified 43 different mtDNA haplotypes resulting from 78 polymorphic sites (46 in HVI and 32 in HVII). Most of the variable positions identified in both HVI and HVII were transitions (82.6 and 71.9%, respectively). The frequency of length heteroplasmy in the homopolymeric C-stretch regions was the same for both segments (10.4%). The sequence diversity increased markedly when both hypervariable regions were analyzed jointly (HVI: 0.985, HVII: 0.975, HVI+HVII: 0.994). Accordingly, the probability of two randomly selected sequences matching (random match probability, RMP) decreased from 3.4% (HVI) to 2.6% (HVI+HVII), despite which the RMP values in Georgians remained higher than estimated in most Europeans. This suggests that the variability of maternal lineages tends to be lower in traditional human isolates and, therefore, the potential of discrimination of mtDNA in forensic analysis is more limited in this type of population. The incorporation of HVII data also contributed to the refinement of results regarding the genetic relationships among the samples included in the analyses, which stress the importance of considering HVII in both population and forensic genetics.

Forensic mass screening using mtDNA

At the forensic autopsy of a sexual murder victim, some trace hairs, possibly belonging to the perpetrator, were saved. Initially, the analysis of a pubic hair shaft only revealed the presence of the mitochondrial (mt) DNA haplotype profile consisting of the (CA)(6) allele and the complete hypervariable region 1 (HV1) and 2 (HV2) sequence. Later, typing of some further telogene trace hairs, which had been stored for several years, yielded a nuclear short tandem repeat (STR) profile. We used both the mtDNA haplotype and the STR profile to start a DNA mass screening project involving 2,335 male citizens of the relevant communities. MtDNA screening was carried out by using the CA repeat amplification in combination with an SNP typing procedure based on the restriction site analysis of amplified d-loop sequences. The aim of our paper is to put mass screening with mtDNA up for discussion.

Is the genetic structure of Gran Chaco populations unique? Interregional perspectives on native South American mitochondrial DNA variation

This study reevaluates the hypothesis in Demarchi et al. (2001 Am. J. Phys. Anthropol. 115:199-203) that Gran Chaco peoples demonstrate a unique pattern of genetic diversity due to a distinct regional population history. Specifically, they found populations in the central part of the Gran Chaco, or Central Chaco, to have higher within- and lower between-population mitochondrial DNA (mtDNA) haplogroup frequency variation compared to populations in other South American regions. To test this hypothesis of regional uniqueness, we applied analytical and simulation methods to mtDNA first hypervariable (HVI) region sequence data from a broad set of comparative South and Central American population samples. Contrary to the results of Demarchi et al. (2001 Am. J. Phys. Anthropol. 115:199-203), we found that the Gran Chaco's regional within-population diversity is about average among regions, and populations are highly differentiated from each other. When we limited the scale of analysis to the Central Chaco, a more localized subregion of the Gran Chaco, our results fell more in line with the original findings of Demarchi et al. (2001 Am. J. Phys. Anthropol. 115:199-203). Still, we conclude that neither the Gran Chaco regional pattern, nor the Central Chaco subregional pattern, is unique within South America. Nonetheless, the Central Chaco pattern accords well with the area's history, including pre-European contact lifeways and the documented historical use of the area as an interregional crossroads. However, we cannot exclude post-European contact disruption of traditional mating networks as an equally plausible explanation for the observed diversity pattern. Finally, these results additionally inform broader models of South American genetic diversity. While other researchers proposed an east-west continental division in patterns of genetic variation (e.g., Fuselli et al. 2003 Mol. Biol. Evol. 20:1682-1691), we found that in the geographically intermediate Central Chaco, a strict east-west divide in genetic variation breaks down. We suggest that future genetic characterizations of the continent, and subsequent interpretations of evolutionary history, involve a broad regional sampling of South American populations.

Mitochondrial DNA instability in malignant melanoma of the skin is mostly restricted to nodular and metastatic stages

Ultraviolet (UV) radiation is thought to be a major contributor to the development of sporadic malignant melanoma of the skin. It may induce alterations in genomic or mitochondrial DNA (mtDNA), especially C to T or CC to TT changes. Mutations or other alterations in mtDNA have been reported in a variety of human cancers and may be due to different mechanisms. In this study, we have attempted to elucidate whether aberrations in the mtDNA of melanoma are due to UV radiation or other factors by investigating two parts of the mitochondrial D-loop and two mitochondrial genes, as well as looking for the delta4977 mtDNA deletion and mtDNA duplications, in 61 primary malignant melanomas and neighbouring normal skin tissue (in 70% of primary tumours; otherwise, corresponding blood samples). Point mutations were a rare feature, occurring in only seven tumour samples and never as a C to T change, whereas mtDNA instability in the D-loop (mtMSI) was found in 13% of primary nodular tumours and 20% of metastases. A de novo delta4977 mtDNA deletion was demonstrated in 10% of melanomas; in 20% of patients, mtDNA duplications and/or the delta4977 mtDNA deletion was detectable. Our data indicate that mtDNA alterations in malignant melanoma are not induced by UV radiation. In addition, point mutations and mtMSI were mostly a feature of nodular and metastatic melanoma samples.

The molecular dissection of mtDNA haplogroup H confirms that the Franco-Cantabrian glacial refuge was a major source for the European gene pool

Complete sequencing of 62 mitochondrial DNAs (mtDNAs) belonging (or very closely related) to haplogroup H revealed that this mtDNA haplogroup--by far the most common in Europe--is subdivided into numerous subhaplogroups, with at least 15 of them (H1-H15) identifiable by characteristic mutations. All the haplogroup H mtDNAs found in 5,743 subjects from 43 populations were then screened for diagnostic markers of subhaplogroups H1 and H3. This survey showed that both subhaplogroups display frequency peaks, centered in Iberia and surrounding areas, with distributions declining toward the northeast and southeast--a pattern extremely similar to that previously reported for mtDNA haplogroup V. Furthermore, the coalescence ages of H1 and H3 (~11,000 years) are close to that previously reported for V. These findings have major implications for the origin of Europeans, since they attest that the Franco-Cantabrian refuge area was indeed the source of late-glacial expansions of hunter-gatherers that repopulated much of Central and Northern Europe from ~15,000 years ago. This has also some implications for disease studies. For instance, the high occurrence of H1 and H3 in Iberia led us to re-evaluate the haplogroup distribution in 50 Spanish families affected by nonsyndromic sensorineural deafness due to the A1555G mutation. The survey revealed that the previously reported excess of H among these families is caused entirely by H3 and is due to a major, probably nonrecent, founder event.

The Longue Durée of genetic ancestry: multiple genetic marker systems and Celtic origins on the Atlantic facade of Europe

Celtic languages are now spoken only on the Atlantic facade of Europe, mainly in Britain and Ireland, but were spoken more widely in western and central Europe until the collapse of the Roman Empire in the first millennium a.d. It has been common to couple archaeological evidence for the expansion of Iron Age elites in central Europe with the dispersal of these languages and of Celtic ethnicity and to posit a central European "homeland" for the Celtic peoples. More recently, however, archaeologists have questioned this "migrationist" view of Celtic ethnogenesis. The proposition of a central European ancestry should be testable by examining the distribution of genetic markers; however, although Y-chromosome patterns in Atlantic Europe show little evidence of central European influence, there has hitherto been insufficient data to confirm this by use of mitochondrial DNA (mtDNA). Here, we present both new mtDNA data from Ireland and a novel analysis of a greatly enlarged European mtDNA database. We show that mtDNA lineages, when analyzed in sufficiently large numbers, display patterns significantly similar to a large fraction of both Y-chromosome and autosomal variation. These multiple genetic marker systems indicate a shared ancestry throughout the Atlantic zone, from northern Iberia to western Scandinavia, that dates back to the end of the last Ice Age.

Relationship between mitochondrial DNA instability, mitochondrial DNA large deletions, and nuclear microsatellite instability in head and neck squamous cell carcinomas

Mitochondrial DNA (mtDNA) mutations in coding and noncoding regions have been reported in a variety of human cancers. Despite a greater number of studies, the relationship between such alterations and nuclear microsatellite instability (nMSI) of the tumor cells remains controversial. To contribute new data to this discussion, we investigated head and neck squamous cell carcinomas (HNSCC) for mutations and mitochondrial microsatellite instability (mtMSI) in 2 parts of the mitochondrial D-loop as well as mutations in 2 mitochondrial genes and for the delta4977 mtDNA deletion. These results were compared with data of an analysis for microsatellite instability at IGFIIR, hMSH3, hMSH6, and 5 dinucleotide repeats. We found mtMSI, low nMSI, and high nMSI in 42%, 36%, and 13% of HNSCC primary tumors, respectively. A de novo delta4977 mtDNA deletion could be demonstrated in 25% of HNSCCs. A correlation between mtMSI and nMSI or between a de novo occurrence of the delta4977 mtDNA deletion and nMSI could not be detected in our HNSCC samples (P values 0.527 and 0.078, respectively). Nevertheless, the high rate of mtMSI suggests an involvement of mtDNA alterations in the tumorigenesis of this head and neck cancer and supports the proposal that this aberration may be a new tumor marker.

The western and eastern roots of the Saami--the story of genetic "outliers" told by mitochondrial DNA and Y chromosomes

The Saami are regarded as extreme genetic outliers among European populations. In this study, a high-resolution phylogenetic analysis of Saami genetic heritage was undertaken in a comprehensive context, through use of maternally inherited mitochondrial DNA (mtDNA) and paternally inherited Y-chromosomal variation. DNA variants present in the Saami were compared with those found in Europe and Siberia, through use of both new and previously published data from 445 Saami and 17,096 western Eurasian and Siberian mtDNA samples, as well as 127 Saami and 2,840 western Eurasian and Siberian Y-chromosome samples. It was shown that the "Saami motif" variant of mtDNA haplogroup U5b is present in a large area outside Scandinavia. A detailed phylogeographic analysis of one of the predominant Saami mtDNA haplogroups, U5b1b, which also includes the lineages of the "Saami motif," was undertaken in 31 populations. The results indicate that the origin of U5b1b, as for the other predominant Saami haplogroup, V, is most likely in western, rather than eastern, Europe. Furthermore, an additional haplogroup (H1) spread among the Saami was virtually absent in 781 Samoyed and Ob-Ugric Siberians but was present in western and central European populations. The Y-chromosomal variety in the Saami is also consistent with their European ancestry. It suggests that the large genetic separation of the Saami from other Europeans is best explained by assuming that the Saami are descendants of a narrow, distinctive subset of Europeans. In particular, no evidence of a significant directional gene flow from extant aboriginal Siberian populations into the haploid gene pools of the Saami was found.

Mitochondrial diversity of a northeast German population sample

Mitochondrial DNA sequences of the hypervariable regions HV I and HV II were analyzed in 300 unrelated individuals born and living in the northeast corner of Germany (Western Pomerania) to generate a database for forensic identification purposes in this region. Sequence polymorphism were detected using PCR and direct sequencing analysis. A total of 242 different haplotypes were found as determined by 147 variable positions. The most frequent haplotype (263G, 315.1C) was found in 10 individuals and is also the most common sequence in Europe. Three other haplotypes were shared by 5 individuals, 2 sequences by 4, 8 haplotypes by 3, 15 sequences by 2 persons, and 213 sequences were unique. The genetic diversity was estimated to be 0.99 and the probability of two random individuals showing identical mitochondrial DNA (mtDNA) haplotypes is 0.6%. A comparison with other studies from Germany showed only little differences in the distribution of haplogroups. Nevertheless, one frequent haplotype in northeast Germany (five unrelated individuals) could only rarely be found in other German and European regions. Our results may indicate that despite a high admixture proportion in the German population some regions could demonstrate certain characteristic features.