Traces of archaic mitochondrial lineages persist in Austronesian-speaking Formosan populations

Association of HLA-C*07:359 with HLA-A, -B, and -DRB1 alleles in Taiwanese

Objectives

It is thought that Taiwanese indigenous people were the "first people" to populate Taiwan (Formosa) having been there for over 5000 years, preceding the Dutch colonization (from 1624 to 1662) and Spanish colonization (from 1626 to 1642). Taiwan's indigenes, represented by Austronesian language speakers, currently constitute approximately 2% of the total population in Taiwan. It is unknown whether they evolved from Taiwan's Paleolithic or Neolithic cultures, arrived during or after the Neolithic period from China or Southeast Asia or both. HLA studies on the Taiwanese indigenous population have found several intriguing genetic information showing one or two relatively frequently observed alleles and a small number of relatively less frequently observed ones. We report here a relatively frequently observed HLA-C*07:359 allele in the Taiwanese indigenous population, its linkage with HLA-B*39:01, and its probable associated HLA haplotype in two Taiwanese indigenous families. HLA-C*07:359 is a rarely observed allele in the HLA-C locus in the world populations. The objective of this study is to report the allele HLA-C*07:359 that is more frequently found in the Taiwanese population, especially in the Taiwanese indigenous people, to demonstrate that it has a close linkage with HLA-B*39:01 allele in the HLA-B locus and to show the plausible deduced HLA-A-C-B-DRB1-DQB1 haplotypes in association with HLA-C*07:359 in two families of Taiwanese indigenous unrelated individuals.

Materials and Methods

The samples were peripheral whole blood, with dipotassium ethylenediaminetetraacetic acid and/or acid citrate dextrose anticoagulation additives. The sequence-based typing method was employed to confirm the low incidence of the allele of HLA-C*07:359 observed in Taiwanese. Polymerase chain reaction was carried out to amplify exons 2, 3, and 4 of the HLA-A,-B,-C,-DRB1 and-DQB1 loci with group-specific primer sets. Amplicons were sequenced using the BigDye Terminator Cycle Sequencing Ready Reaction Kit in both directions according to the manufacturer's protocol.

Results

C*07:359 is an uncommon allele in the HLA-C locus in the world general population, according to our literature review. However, in this study, it is observed in the general Taiwanese population (frequency 0.41%), especially in the Taiwanese indigenous people at a frequency of 0.23%. In addition, we deduced two probable HLA haplotypes in association with C*07:359 in two indigenous families: A*24:02-C*07:359-B*39:01-DRB1*04:36 and A*24:02-C*07:359-B*39:01-DRB1*04:04.

Conclusion

The two deduced HLA haplotypes associated with the uncommon C*07:359 allele that we report here are valuable for HLA tissue typing laboratories for reference purposes and for stem cell transplantation donor search coordinators to determine the likelihood of finding compatible donors in unrelated bone marrow donor registries for patients bearing the uncommon HLA allele. Since C*07:359 was found mostly in the Taiwanese indigenous population, we think the allele and its haplotypes we report here are important in population and anthropological studies.

Indigenous DNA as a metaphor: Nation-building and scientific debates on the rediscovery of Taiwanese ancestry

In this paper, I investigate the co-production of genetic research and national politics in post-martial law Taiwan. This entails analyzing two co-produced phenomena: the nationalization of biomedicine-in which the national discourse over racial/ethnic categories and ancestral origin increasingly shapes scientists' biomedical research; and the biomedicalization of the nation-in which people in public discourse increasingly use biomedical categories in characterizing national differences and identities. I analyze how the production and representation of scientific knowledge of the ancestral origins and genetic make-up of Taiwan have been embedded in Taiwanese politics. This includes the emergence of a new categorization into four great ethnic groups, multiculturalism, and the assertion of a distinct Taiwanese national identity, particularly in response to the People's Republic of China's claims of common ancestry. I also examine how the scientific findings produced in the lab have spilled out into both Taiwan and China through journals, media, history textbooks, and public disputes since the 1990s and brought about significant social impact.

Whole mitochondrial genome analysis in highland Tibetans: further matrilineal genetic structure exploration

Introduction: The Qinghai-Tibet Plateau is one of the last terrestrial environments conquered by modern humans. Tibetans are among the few high-altitude settlers in the world, and understanding the genetic profile of Tibetans plays a pivotal role in studies of anthropology, genetics, and archaeology. Methods: In this study, we investigated the maternal genetic landscape of Tibetans based on the whole mitochondrial genome collected from 145 unrelated native Lhasa Tibetans. Molecular diversity indices, haplotype diversity (HD), Tajima's D and Fu's Fs were calculated and the Bayesian Skyline Plot was obtained to determining the genetic profile and population fluctuation of Lhasa Tibetans. To further explore the genetic structure of Lhasa Tibetans, we collected 107 East Asian reference populations to perform principal component analysis (PCA), multidimensional scaling (MDS), calculated Fst values and constructed phylogenetic tree. Results: The maternal genetic landscape of Tibetans showed obvious East Asian characteristics, M9a (28.28%), R (11.03%), F1 (12.41%), D4 (9.66%), N (6.21%), and M62 (4.14%) were the dominant haplogroups. The results of PCA, MDS, Fst and phylogenetic tree were consistent: Lhasa Tibetans clustered with other highland Tibeto-Burman speakers, there was obvious genetic homogeneity of Tibetans in Xizang, and genetic similarity between Tibetans and northern Han people and geographically adjacent populations was found. In addition, specific maternal lineages of Tibetans also be determined in this study. Discussion: In general, this study further shed light on long-time matrilineal continuity on the Tibetan Plateau and the genetic connection between Tibetans and millet famers in the Yellow River Basin, and further revealed that multiple waves of population interaction and admixture during different historical periods between lowland and highland populations shaped the maternal genetic profile of Tibetans.

Association of rs9939609 in FTO with BMI among Polynesian peoples living in Aotearoa New Zealand and other Pacific nations

The fat mass and obesity associated (FTO) locus consistently associates with higher body mass index (BMI) across diverse ancestral groups. However, previous small studies of people of Polynesian ancestries have failed to replicate the association. In this study, we used Bayesian meta-analysis to test rs9939609, the most replicated FTO variant, for association with BMI with a large sample (n = 6095) of Aotearoa New Zealanders of Polynesian (Māori and Pacific) ancestry and of Samoan people living in the Independent State of Samoa and in American Samoa. We did not observe statistically significant association within each separate Polynesian subgroup. Bayesian meta-analysis of the Aotearoa New Zealand Polynesian and Samoan samples resulted in a posterior mean effect size estimate of +0.21 kg/m2, with a 95% credible interval [+0.03 kg/m2, +0.39 kg/m2]. While the Bayes Factor (BF) of 0.77 weakly favors the null, the BF = 1.4 Bayesian support interval is [+0.04, +0.20]. These results suggest that rs9939609 in FTO may have a similar effect on mean BMI in people of Polynesian ancestries as previously observed in other ancestral groups.

Diversity and distribution of mitochondrial DNA in non-Austronesian-speaking Taiwanese individuals

Many studies have described the diversity of Austronesian-speaking Taiwanese people to shed more light on their origin and their connection with the "Out of Taiwan" migrations. However, the genetic relationship between the non-Austronesian-speaking groups of Taiwan and the populations of continental Asia is still unclear. Here, we studied the diversity of mtDNA in 767 non-Austronesian speakers from 16 locations in Taiwan using partial sequencing obtained from the hypervariable segment I (HVS-I) and coding regions 8,001-9,000 and 9.801-10,900 and 85 complete mtDNA genome sequences. Bayesian analysis of population structure was used to examine their relationship with over 3662 individuals representing indigenous groups of Taiwan, continental East Asia, Japan, and Island Southeast Asia. The whole analysis identified 278 haplotypes. Complete genomes revealed 62 novel subhaplogroups, of which 31 were exclusive to Taiwan. Estimates of coalescence times of all subhaplogroups showed peaks of diversification greater than 5.0 kya, likely characterizing gene flow from continental East Asian groups but not excluding in situ Taiwanese ancestry. Furthermore, a significant number of clades exclusive to non-Austronesian speakers of Taiwan (NAN_Tw) showed coalescence peaks between 1.0 and 2.6 kya, suggesting possible late Neolithic to early metal age settlements of NAN_Tw and local expansion in Taiwan.

Cultural transmission of traditional songs in the Ryukyu Archipelago

Geographic patterns of cultural variations are affected by how cultural traits are transmitted within and between populations. It has been argued that cultural traits are transmitted in different manners depending on their characteristics; for example, words for basic concepts are less liable to horizontal transmission between populations (i.e., borrowing) than other words. Here we examine the geographic variation of traditional songs in the Ryukyu Archipelago, southwestern islands of Japan, to explore cultural evolution of music with a focus on different social contexts in which songs are sung. Published scores of 1,342 traditional songs are coded using the CantoCore song classification scheme and distances between the songs are calculated from the codings. Neighbor-Net graphs of regions/islands are generated on the basis of the musical distances, and delta scores are obtained to examine the treelikeness of the networks. We also perform analysis of molecular variance (AMOVA) to evaluate the extent of musical diversification among regions/islands. Our results suggest that horizontal transmission between populations has played a greater role in the formation of musical diversity than that of linguistic diversity in the Ryukyu Archipelago and that the social context in which songs are sung has an effect on how they are transmitted within and between populations. In addition, we compare the observed patterns of song diversity among regions/islands with those of lexical and mitochondrial-DNA (mtDNA) diversity, showing that the variation of songs sung in the "work" context are associated with the linguistic variation, whereas no association is found between the musical and genetic variation.

Consequences of the Last Glacial Period on the Genetic Diversity of Southeast Asians

The last glacial period (LGP) promoted a loss of genetic diversity in Paleolithic populations of modern humans from diverse regions of the world by range contractions and habitat fragmentation. However, this period also provided some currently submersed lands, such as the Sunda shelf in Southeast Asia (SEA), that could have favored the expansion of our species. Concerning the latter, still little is known about the influence of the lowering sea level on the genetic diversity of current SEA populations. Here, we applied approximate Bayesian computation, based on extensive spatially explicit computer simulations, to evaluate the fitting of mtDNA data from diverse SEA populations with alternative evolutionary scenarios that consider and ignore the LGP and migration through long-distance dispersal (LDD). We found that both the LGP and migration through LDD should be taken into consideration to explain the currently observed genetic diversity in these populations and supported a rapid expansion of first populations throughout SEA. We also found that temporarily available lands caused by the low sea level of the LGP provided additional resources and migration corridors that favored genetic diversity. We conclude that migration through LDD and temporarily available lands during the LGP should be considered to properly understand and model the first expansions of modern humans.

Ethnic disparity in metabolic syndrome and related obesity and health behavior: a community study in Taiwan

BACKGROUND

As studies on ethnic disparities in metabolic syndrome and its risk factors in Taiwan are still rare, the aims of this study were: (1) to detect the differences in the rates of metabolic syndrome, obesity and health behaviors between two ethnic groups (indigenous Tsou and nonindigenous Han) living in the same area and with similar age and sex distributions; (2) to examine whether ethnicity per se plays a significant role in the occurrence of metabolic syndrome, while taking other risk factors including sociodemographic characteristics, obesity and health behaviors into consideration.

METHODS

This is a cross-sectional study using data from a community survey conducted in Chiayi County in southwestern Taiwan. A frequency matching strategy by age and sex with a ratio of 1 (Tsou) to 3 (Han) was applied to select a comparable sample between both ethnic groups (667 Tsou and 2001 Han) from among the survey participants. Furthermore, participants with cardiometabolic diseases diagnosed before the surveyed day were excluded to avoid confounding any associated risk factors for developing metabolic syndrome (MS). A final analytic sample of 1482 remained. The used information included sociodemographic characteristics, medical histories, health behaviors, and the concentrations of triglycerides, cholesterol, and glucose.

RESULTS

Indigenous Tsou had significantly higher rates of metabolic syndromes, obesity and unhealthy behaviors than their Han counterparts (MS: 54.0% vs. 29.1%, obesity: 54.0% vs. 23.2%, drinking alcohol: 17.5% vs. 13.6%, and higher intake of fried food: 6.4% vs. 4.4%), even though they were similar in age and sex distributions. The significant risk factors for subsequently developing MS included being indigenous Tsou (adjusted POR = 2.62, P < 0.001), older, single, and obese. Stratified analyses on the risk factors for developing MS by health behaviors and by obese problems also indicated increased risks of being indigenous Tsou.

CONCLUSIONS

There existed ethnic differences in the rates of metabolic syndrome, obesity, and health behaviors. Ethnicity per se did play a significant role in developing MS; in particular indigenous Tsou people had increased risks, suggesting possible biological reasons rooted in their origins that need further exploration. In addition, unhealthy behaviors may potentially have an indirect effect on developing MS via their effect on obesity.

Detecting Genetic Ancestry and Adaptation in the Taiwanese Han People

The Taiwanese people are composed of diverse indigenous populations and the Taiwanese Han. About 95% of the Taiwanese identify themselves as Taiwanese Han, but this may not be a homogeneous population because they migrated to the island from various regions of continental East Asia over a period of 400 years. Little is known about the underlying patterns of genetic ancestry, population admixture, and evolutionary adaptation in the Taiwanese Han people. Here, we analyzed the whole-genome single-nucleotide polymorphism genotyping data from 14,401 individuals of Taiwanese Han collected by the Taiwan Biobank and the whole-genome sequencing data for a subset of 772 people. We detected four major genetic ancestries with distinct geographic distributions (i.e., Northern, Southeastern, Japonic, and Island Southeast Asian ancestries) and signatures of population mixture contributing to the genomes of Taiwanese Han. We further scanned for signatures of positive natural selection that caused unusually long-range haplotypes and elevations of hitchhiked variants. As a result, we identified 16 candidate loci in which selection signals can be unambiguously localized at five single genes: CTNNA2, LRP1B, CSNK1G3, ASTN2, and NEO1. Statistical associations were examined in 16 metabolic-related traits to further elucidate the functional effects of each candidate gene. All five genes appear to have pleiotropic connections to various types of disease susceptibility and significant associations with at least one metabolic-related trait. Together, our results provide critical insights for understanding the evolutionary history and adaption of the Taiwanese Han population.

Maternal lineage of Nicobari pig (Sus scrofa nicobaricus) correlated with migration of Nicobarese, a native tribal population of Andaman and Nicobar Islands, India

Nicobari pig is reared by Nicobarese, a native tribal population of Andaman and Nicobar Islands. Nicobari pig has maintained its genetic identity due to geographical isolation. This communication is the first report on maternal inheritance of Nicobari pigs. DNA polymorphism data showed seven haplotypes. D-loop sequence information and mitogenome analysis were able to earmark Nicobari pigs to Asian clade. The domestication process of pigs and its expansion pattern help to understand human migration pattern. Based on this hypothesis, this communication elucidates the probable origin of Nicobarese. Earlier studies indicated that Nicobarese had genetic affinities to races distributed in China, Malaysia and Thailand. Our data on maternal inheritance of Nicobari pig correlates with the data on migration of Nicobarese. Moreover, we could establish a novel connection of Nicobarese with people of Northeastern parts of India, Philippines and Vietnam through phylogenetic signal and geographical provenance of Nicobari pig. We further concluded that migration of Nicobarese happened during Western route of migration (WRM) ∼4000 years before present. Therefore, we propose one wave hypothesis of peopling of Nicobar based on our study and existence of Ausrtroasiatic language, Mon-Khmer in these islands.

Paternal gene pool of Malays in Southeast Asia and its applications for the early expansion of Austronesians

OBJECTIVES

The origin and differentiation of Austronesian populations and their languages have long fascinated linguists, archeologists, and geneticists. However, the founding process of Austronesians and when they separated from their close relatives, such as the Daic and Austro-Asiatic populations in the mainland of Asia, remain unclear. In this study, we explored the paternal origin of Malays in Southeast Asia and the early differentiation of Austronesians.

MATERIALS AND METHODS

We generated whole Y-chromosome sequences of 50 Malays and co-analyzed 200 sequences from other Austronesians and related populations. We generated a revised phylogenetic tree with time estimation.

RESULTS

We identified six founding paternal lineages among the studied Malays samples. These founding lineages showed a surprisingly coincident expansion age at 5000 to 6000 years ago. We also found numerous mostly close related samples of the founding lineages of Malays among populations from Mainland of Asia.

CONCLUSION

Our analyses provided a refined phylogenetic resolution for the dominant paternal lineages of Austronesians found by previous studies. We suggested that the co-expansion of numerous founding paternal lineages corresponds to the initial differentiation of the most recent common ancestor of modern Austronesians. The splitting time and divergence pattern in perspective of paternal Y-chromosome evidence are highly consistent with the previous theories of ethnologists, linguists, and archeologists.

Ancient Jomon genome sequence analysis sheds light on migration patterns of early East Asian populations

Anatomically modern humans reached East Asia more than 40,000 years ago. However, key questions still remain unanswered with regard to the route(s) and the number of wave(s) in the dispersal into East Eurasia. Ancient genomes at the edge of the region may elucidate a more detailed picture of the peopling of East Eurasia. Here, we analyze the whole-genome sequence of a 2,500-year-old individual (IK002) from the main-island of Japan that is  characterized with a typical Jomon culture. The phylogenetic analyses support multiple waves of migration, with IK002 forming a basal lineage to the East and Northeast Asian genomes examined, likely representing some of the earliest-wave migrants who went north from Southeast Asia to East Asia. Furthermore, IK002 shows strong genetic affinity with the indigenous Taiwan aborigines, which may support a coastal route of the Jomon-ancestry migration. This study highlights the power of ancient genomics to provide new insights into the complex history of human migration into East Eurasia.

Takashi Gakuhari, Shigeki Nakagome et al. report the genomic analysis on a 2.5 kya individual from the ancient Jomon culture in present-day Japan. Phylogenetic analysis with comparison to other Eurasian sequences suggests early migration patterns in Asia and provides insight into the genetic affinities between peoples of the region.

Genetic diversity of the Thao people of Taiwan using Y-chromosome, mitochondrial DNA and HLA gene systems

BACKGROUND

Despite attempts in retracing the history of the Thao people in Taiwan using folktales, linguistics, physical anthropology, and ethnic studies, their history remains incomplete. The heritage of Thao has been associated with the Pazeh Western plains peoples and several other mountain peoples of Taiwan. In the last 400 years, their culture and genetic profile have been reshaped by East Asian migrants. They were displaced by the Japanese and the construction of a dam and almost faced extinction. In this paper, genetic information from mitochondrial DNA (mtDNA), Histoleucocyte antigens (HLA), and the non-recombining Y chromosome of 30 Thao individuals are compared to 836 other Taiwan Mountain and Plains Aborigines (TwrIP & TwPp), 384 Non-Aboriginal Taiwanese (non-TwA) and 149 Continental East Asians.

RESULTS

The phylogeographic analyses of mtDNA haplogroups F4b and B4b1a2 indicated gene flow between Thao, Bunun, and Tsou, and suggested a common ancestry from 10,000 to 3000 years ago. A claim of close contact with the heavily Sinicized Pazeh of the plains was not rejected and suggests that the plains and mountain peoples most likely shared the same Austronesian agriculturist gene pool in the Neolithic.

CONCLUSIONS

Having been moving repeatedly since their arrival in Taiwan between 6000 and 4500 years ago, the Thao finally settled in the central mountain range. They represent the last plains people whose strong bonds with their original culture allowed them to preserve their genetic heritage, despite significant gene flow from the mainland of Asia. Representing a considerable contribution to the genealogical history of the Thao people, the findings of this study bear on ongoing anthropological and linguistic debates on their origin.

Cebú, Thailand and Taiwanese aboriginal populations according to Y-STR loci

Here we report for the first time the Y27-STR Yfiler plus profiles of the insular population of Cebú in the central region of the Philippine Archipelago and the general continental population of Thailand, two strategic locations of interest in connection with the Austronesian expansion. Traditionally, the peopling of Taiwan has been envisioned as a single wave of agriculturists migrating from mainland Southeast Asia. Yet, more recent data support a scenario in which a number of migrations from the continent populated the island. Genetic affinity parameters from this study indicate that certain Formosan tribes are genetically closer to geographical distant populations in the Solomon Island than to other nearby Taiwanese tribes. Furthermore, Taiwanese aboriginal populations in this study partition into three clusters, one associated with populations from the Philippines and Thailand, a second one segregating with populations of the Solomon Islands and a third grouping made up exclusively of Taiwanese aboriginal tribes. The populations within each of these three clusters exhibit different degrees of differentiation among them suggesting unique population histories. All together, these differential genetic affinities of specific Taiwanese tribes to groups from different geographical regions and to each other are compatible with multiple origins of the Austronesian expansion from Formosa as well as from mainland Southeast Asia.

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Partitioning of Taiwanese aboriginal populations into three clusters.

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The middle cluster includes the populations from Cebú and Thailand.

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A second cluster segregates with populations of the Solomon Islands.

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A third cluster is made up exclusively of Taiwanese aboriginal tribes.

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Some Formosan tribes are genetically closer to geographical distant Solomon Island populations.

Complete human mtDNA genome sequences from Vietnam and the phylogeography of Mainland Southeast Asia

Vietnam is an important crossroads within Mainland Southeast Asia (MSEA) and a gateway to Island Southeast Asia, and as such exhibits high levels of ethnolinguistic diversity. However, comparatively few studies have been undertaken of the genetic diversity of Vietnamese populations. In order to gain comprehensive insights into MSEA mtDNA phylogeography, we sequenced 609 complete mtDNA genomes from individuals belonging to five language families (Austroasiatic, Tai-Kadai, Hmong-Mien, Sino-Tibetan and Austronesian) and analyzed them in comparison with sequences from other MSEA countries and Taiwan. Within Vietnam, we identified 399 haplotypes belonging to 135 haplogroups; among the five language families, the sequences from Austronesian groups differ the most from the other groups. Phylogenetic analysis revealed 111 novel Vietnamese mtDNA lineages. Bayesian estimates of coalescence times and associated 95% HPD for these show a peak of mtDNA diversification around 2.5–3 kya, which coincides with the Dong Son culture, and thus may be associated with the agriculturally-driven expansion of this culture. Networks of major MSEA haplogroups emphasize the overall distinctiveness of sequences from Taiwan, in keeping with previous studies that suggested at most a minor impact of the Austronesian expansion from Taiwan on MSEA. We also see evidence for population expansions across MSEA geographic regions and language families.

Phylogeography of Y-chromosome haplogroup O3a2b2-N6 reveals patrilineal traces of Austronesian populations on the eastern coastal regions of Asia

Austronesian diffusion is considered one of the greatest dispersals in human history; it led to the peopling of an extremely vast region, ranging from Madagascar in the Indian Ocean to Easter Island in Remote Oceania. The Y-chromosome haplogroup O3a2b*-P164(xM134), a predominant paternal lineage of Austronesian populations, is found at high frequencies in Polynesian populations. However, the internal phylogeny of this haplogroup remains poorly investigated. In this study, we analyzed -seventeen Y-chromosome sequences of haplogroup O3a2b*-P164(xM134) and generated a revised phylogenetic tree of this lineage based on 310 non-private Y-chromosome polymorphisms. We discovered that all available O3a2b*-P164(xM134) samples belong to the newly defined haplogroup O3a2b2-N6 and samples from Austronesian populations belong to the sublineage O3a2b2a2-F706. Additionally, we genotyped a series of Y-chromosome polymorphisms in a large collection of samples from China. We confirmed that the sublineage O3a2b2a2b-B451 is unique to Austronesian populations. We found that O3a2b2-N6 samples are widely distributed on the eastern coastal regions of Asia, from Korea to Vietnam. Furthermore, we propose- that the O3a2b2a2b-B451 lineage represents a genetic connection between ancestors of Austronesian populations and ancient populations in North China, where foxtail millet was domesticated about 11,000 years ago. The large number of newly defined Y-chromosome polymorphisms and the revised phylogenetic tree of O3a2b2-N6 will be helpful to explore the origin of proto-Austronesians and the early diffusion process of Austronesian populations.

Genomics Study of Mycobacterium tuberculosis Strains from Different Ethnic Populations in Taiwan

To better understand the transmission and evolution of Mycobacterium tuberculosis (MTB) in Taiwan, six different MTB isolates (representatives of the Beijing ancient sublineage, Beijing modern sublineage, Haarlem, East-African Indian, T1, and Latin-American Mediterranean (LAM)) were characterized and their genomes were sequenced. Discriminating among large sequence polymorphisms (LSPs) that occur once versus those that occur repeatedly in a genomic region may help to elucidate the biological roles of LSPs and to identify the useful phylogenetic relationships. In contrast to our previous LSP-based phylogeny, the sequencing data allowed us to determine actual genetic distances and to define precisely the phylogenetic relationships between the main lineages of the MTB complex. Comparative genomics analyses revealed more nonsynonymous substitutions than synonymous changes in the coding sequences. Furthermore, MTB isolate M7, a LAM-3 clinical strain isolated from a patient of Taiwanese aboriginal origin, is closely related to F11 (LAM), an epidemic tuberculosis strain isolated in the Western Cape of South Africa. The PE/PPE protein family showed a higher dn/ds ratio compared to that for all protein-coding genes. Finally, we found Haarlem-3 and LAM-3 isolates to be circulating in the aboriginal community in Taiwan, suggesting that they may have originated with post-Columbus Europeans. Taken together, our results revealed an interesting association with historical migrations of different ethnic populations, thus providing a good model to explore the global evolution and spread of MTB.

Multiplex APLP System for High-Resolution Haplogrouping of Extremely Degraded East-Asian Mitochondrial DNAs

Mitochondrial DNA (mtDNA) serves as a powerful tool for exploring matrilineal phylogeographic ancestry, as well as for analyzing highly degraded samples, because of its polymorphic nature and high copy numbers per cell. The recent advent of complete mitochondrial genome sequencing has led to improved techniques for phylogenetic analyses based on mtDNA, and many multiplex genotyping methods have been developed for the hierarchical analysis of phylogenetically important mutations. However, few high-resolution multiplex genotyping systems for analyzing East-Asian mtDNA can be applied to extremely degraded samples. Here, we present a multiplex system for analyzing mitochondrial single nucleotide polymorphisms (mtSNPs), which relies on a novel amplified product-length polymorphisms (APLP) method that uses inosine-flapped primers and is specifically designed for the detailed haplogrouping of extremely degraded East-Asian mtDNAs. We used fourteen 6-plex polymerase chain reactions (PCRs) and subsequent electrophoresis to examine 81 haplogroup-defining SNPs and 3 insertion/deletion sites, and we were able to securely assign the studied mtDNAs to relevant haplogroups. Our system requires only 1×10-13 g (100 fg) of crude DNA to obtain a full profile. Owing to its small amplicon size (<110 bp), this new APLP system was successfully applied to extremely degraded samples for which direct sequencing of hypervariable segments using mini-primer sets was unsuccessful, and proved to be more robust than conventional APLP analysis. Thus, our new APLP system is effective for retrieving reliable data from extremely degraded East-Asian mtDNAs.

Multi-layered population structure in Island Southeast Asians

The history of human settlement in Southeast Asia has been complex and involved several distinct dispersal events. Here, we report the analyses of 1825 individuals from Southeast Asia including new genome-wide genotype data for 146 individuals from three Mainland Southeast Asian (Burmese, Malay and Vietnamese) and four Island Southeast Asian (Dusun, Filipino, Kankanaey and Murut) populations. While confirming the presence of previously recognised major ancestry components in the Southeast Asian population structure, we highlight the Kankanaey Igorots from the highlands of the Philippine Mountain Province as likely the closest living representatives of the source population that may have given rise to the Austronesian expansion. This conclusion rests on independent evidence from various analyses of autosomal data and uniparental markers. Given the extensive presence of trade goods, cultural and linguistic evidence of Indian influence in Southeast Asia starting from 2.5 kya, we also detect traces of a South Asian signature in different populations in the region dating to the last couple of thousand years.

Quantifying the legacy of the Chinese Neolithic on the maternal genetic heritage of Taiwan and Island Southeast Asia

There has been a long-standing debate concerning the extent to which the spread of Neolithic ceramics and Malay-Polynesian languages in Island Southeast Asia (ISEA) were coupled to an agriculturally driven demic dispersal out of Taiwan 4000 years ago (4 ka). We previously addressed this question using founder analysis of mitochondrial DNA (mtDNA) control-region sequences to identify major lineage clusters most likely to have dispersed from Taiwan into ISEA, proposing that the dispersal had a relatively minor impact on the extant genetic structure of ISEA, and that the role of agriculture in the expansion of the Austronesian languages was therefore likely to have been correspondingly minor. Here we test these conclusions by sequencing whole mtDNAs from across Taiwan and ISEA, using their higher chronological precision to resolve the overall proportion that participated in the "out-of-Taiwan" mid-Holocene dispersal as opposed to earlier, postglacial expansions in the Early Holocene. We show that, in total, about 20% of mtDNA lineages in the modern ISEA pool result from the "out-of-Taiwan" dispersal, with most of the remainder signifying earlier processes, mainly due to sea-level rises after the Last Glacial Maximum. Notably, we show that every one of these founder clusters previously entered Taiwan from China, 6-7 ka, where rice-farming originated, and remained distinct from the indigenous Taiwanese population until after the subsequent dispersal into ISEA.

Resolving the ancestry of Austronesian-speaking populations

There are two very different interpretations of the prehistory of Island Southeast Asia (ISEA), with genetic evidence invoked in support of both. The "out-of-Taiwan" model proposes a major Late Holocene expansion of Neolithic Austronesian speakers from Taiwan. An alternative, proposing that Late Glacial/postglacial sea-level rises triggered largely autochthonous dispersals, accounts for some otherwise enigmatic genetic patterns, but fails to explain the Austronesian language dispersal. Combining mitochondrial DNA (mtDNA), Y-chromosome and genome-wide data, we performed the most comprehensive analysis of the region to date, obtaining highly consistent results across all three systems and allowing us to reconcile the models. We infer a primarily common ancestry for Taiwan/ISEA populations established before the Neolithic, but also detected clear signals of two minor Late Holocene migrations, probably representing Neolithic input from both Mainland Southeast Asia and South China, via Taiwan. This latter may therefore have mediated the Austronesian language dispersal, implying small-scale migration and language shift rather than large-scale expansion.

The genotype distribution of hepatitis C in southeastern Taiwan: Clinical characteristics, racial difference, and therapeutic response

The genotypes of hepatitis C virus (HCV) are associated with the therapeutic response. The racial diversity of Taitung, Taiwan is heterogeneous and a distinguishing feature; how such racial differences influence the genotype distribution and treatment outcome has not been well studied. The objective of this study is to elucidate the HCV genotype distribution in southeastern Taiwan and to analyze the racial differences influencing genotypes and clinical implications. In this retrospective cohort study, we included 343 patients who had been treated with peginterferon-alpha plus ribavirin. The predominant HCV genotype in the southeastern area was type 1 (43.7%), followed by type 2 (37.0%). The proportion of patients mixed with genotype 1 was lower in indigenous vis-à-vis nonindigenous groups (46.1% and 60.2%, p = 0.02). The prevalence of genotype 6 (5.2%) seems higher than in the general population of Taiwan and showed no difference between indigenous and nonindigenous people. The sustained virological response rate was higher in patients without genotype 1, low baseline HCV RNA (≤ 400,000 IU/mL), and in patients who achieved rapid virological response. Racial differences did not influence the therapeutic response. In this retrospective study, the proportion of HCV genotype 6 appeared slightly higher in southeastern areas than in the general population in Taiwan. The prevalence of genotype 1 in indigenous people was statistically lower than in nonindigenous people. Sustained virological response rate did not show any significant difference between indigenous and nonindigenous people in the current study.

Increased Incidence of Mitochondrial Cytochrome C Oxidase 1 Gene Mutations in Patients with Primary Ovarian Insufficiency

Primary ovarian insufficiency (POI), also known as premature ovarian failure (POF), is defined as more than six months of cessation of menses before the age of 40 years, with two serum follicle stimulating hormone (FSH) levels (at least 1 month apart) falling in the menopause range. The cause of POI remains undetermined in the majority of cases, although some studies have reported increased levels of reactive oxygen species (ROS) in idiopathic POF. The role of mitochondrial DNA in the pathogenesis of POI has not been studied extensively. This aim of this study was to uncover underlying mitochondrial genetic defects in patients with POI. The entire region of the mitochondrial genome was amplified in subjects with idiopathic POI (n=63) and age-matched healthy female controls (n=63) using nine pair sets of primers, followed by screening of the mitochondrial genome using an Illumina MiSeq. We identified a total of 96 non-synonymous mitochondrial variations in POI patients and 93 non-synonymous variations in control subjects. Of these, 21 (9 in POI and 12 in control) non-synonymous variations had not been reported previously. Eight mitochondrial cytochrome coxidase 1 (MT-CO1) missense variants were identified in POI patients, whereas only four missense mutations were observed in controls. A high incidence of MT-CO1 missense variants were identified in POI patients compared with controls, and the difference between the groups was statistically significant (13/63 vs. 5/63, p=0.042). Our results show that patients with primary ovarian insufficiency exhibit an increased incidence of mitochondrial cytochrome c oxidase 1 gene mutations, suggesting that MT-CO1 gene mutation may be causal in POI.

Maternal ancestry and population history from whole mitochondrial genomes

MtDNA has been a widely used tool in human evolutionary and population genetic studies over the past three decades. Its maternal inheritance and lack of recombination have offered the opportunity to explore genealogical relationships among individuals and to study the frequency differences of matrilineal clades among human populations at continental and regional scales. The whole mtDNA genome sequencing delivers molecular resolution that is sufficient to distinguish patterns that have arisen over thousands of years. However, mutation rate is highly variable among the functional and non-coding domains of mtDNA which makes it challenging to obtain accurate split dates of the mitochondrial clades. Due to the shallow coalescent time of mitochondrial TMRCA at approximately 100 to 200 thousand years (ky), mtDNA data have only limited power to inform us about the more distant past and the early stages of human evolutionary history. The variation shared by mitochondrial genomes of individuals drawn from different continents outside Africa has been used to illuminate the details of the colonization process of the Old World, whereas regional patterns of variation have been at the focus of studies addressing questions of a more recent time scale. In the era of whole nuclear genome sequencing, mitochondrial genomes are continuing to be informative as a unique tool for the assessment of female-specific aspects of the demographic history of human populations.

Human settlement history between Sunda and Sahul: a focus on East Timor (Timor-Leste) and the Pleistocenic mtDNA diversity

BACKGROUND

Distinct, partly competing, "waves" have been proposed to explain human migration in(to) today's Island Southeast Asia and Australia based on genetic (and other) evidence. The paucity of high quality and high resolution data has impeded insights so far. In this study, one of the first in a forensic environment, we used the Ion Torrent Personal Genome Machine (PGM) for generating complete mitogenome sequences via stand-alone massively parallel sequencing and describe a standard data validation practice.

RESULTS

In this first representative investigation on the mitochondrial DNA (mtDNA) variation of East Timor (Timor-Leste) population including >300 individuals, we put special emphasis on the reconstruction of the initial settlement, in particular on the previously poorly resolved haplogroup P1, an indigenous lineage of the Southwest Pacific region. Our results suggest a colonization of southern Sahul (Australia) >37 kya, limited subsequent exchange, and a parallel incubation of initial settlers in northern Sahul (New Guinea) followed by westward migrations <28 kya.

CONCLUSIONS

The temporal proximity and possible coincidence of these latter dispersals, which encompassed autochthonous haplogroups, with the postulated "later" events of (South) East Asian origin pinpoints a highly dynamic migratory phase.

Ancient DNA and the human settlement of the Pacific: a review

The Pacific region provides unique opportunities to study human evolution including through analyses of ancient DNA. While some of the earliest studies involving ancient DNA from skeletal remains focused on Pacific samples, in the following 25 years, several factors meant that little aDNA research, particularly research focused on human populations, has emerged. This paper briefly presents the genetic evidence for population origins, reviews what ancient DNA work has been undertaken to address human history and evolution in the Pacific region, and argues that the future is bright but research requires a collaborative approach between academic disciplines but also with local communities.

Human paternal and maternal demographic histories: insights from high-resolution Y chromosome and mtDNA sequences

Background

Comparisons of maternally-inherited mitochondrial DNA (mtDNA) and paternally-inherited non-recombining Y chromosome (NRY) variation have provided important insights into the impact of sex-biased processes (such as migration, residence pattern, and so on) on human genetic variation. However, such comparisons have been limited by the different molecular methods typically used to assay mtDNA and NRY variation (for example, sequencing hypervariable segments of the control region for mtDNA vs. genotyping SNPs and/or STR loci for the NRY). Here, we report a simple capture array method to enrich Illumina sequencing libraries for approximately 500 kb of NRY sequence, which we use to generate NRY sequences from 623 males from 51 populations in the CEPH Human Genome Diversity Panel (HGDP). We also obtained complete mtDNA genome sequences from the same individuals, allowing us to compare maternal and paternal histories free of any ascertainment bias.

Results

We identified 2,228 SNPs in the NRY sequences and 2,163 SNPs in the mtDNA sequences. Our results confirm the controversial assertion that genetic differences between human populations on a global scale are bigger for the NRY than for mtDNA, although the differences are not as large as previously suggested. More importantly, we find substantial regional variation in patterns of mtDNA versus NRY variation. Model-based simulations indicate very small ancestral effective population sizes (<100) for the out-of-Africa migration as well as for many human populations. We also find that the ratio of female effective population size to male effective population size (N_f/N_m) has been greater than one throughout the history of modern humans, and has recently increased due to faster growth in N_f than N_m.

Conclusions

The NRY and mtDNA sequences provide new insights into the paternal and maternal histories of human populations, and the methods we introduce here should be widely applicable for further such studies.

Global analysis of saliva as a source of bacterial genes for insights into human population structure and migration studies

BACKGROUND

The genetic diversity of the human microbiome holds great potential for shedding light on the history of our ancestors. Helicobacter pylori is the most prominent example as its analysis allowed a fine-scale resolution of past migration patterns including some that could not be distinguished using human genetic markers. However studies of H. pylori require stomach biopsies, which severely limits the number of samples that can be analysed. By focussing on the house-keeping gene gdh (coding for the glucose-6-phosphate dehydrogenase), on the virulence gene gtf (coding for the glucosyltransferase) of mitis-streptococci and on the 16S-23S rRNA internal transcribed spacer (ITS) region of the Fusobacterium nucleatum/periodonticum-group we here tested the hypothesis that bacterial genes from human saliva have the potential for distinguishing human populations.

RESULTS

Analysis of 10 individuals from each of seven geographic regions, encompassing Africa, Asia and Europe, revealed that the genes gdh and ITS exhibited the highest number of polymorphic sites (59% and 79%, respectively) and most OTUs (defined at 99% identity) were unique to a given country. In contrast, the gene gtf had the lowest number of polymorphic sites (21%), and most OTUs were shared among countries. Most of the variation in the gdh and ITS genes was explained by the high clonal diversity within individuals (around 80%) followed by inter-individual variation of around 20%, leaving the geographic region as providing virtually no source of sequence variation. Conversely, for gtf the variation within individuals accounted for 32%, between individuals for 57% and among geographic regions for 11%. This geographic signature persisted upon extension of the analysis to four additional locations from the American continent. Pearson correlation analysis, pairwise Fst-cluster analysis as well as UniFrac analyses consistently supported a tree structure in which the European countries clustered tightly together and branched with American countries and South Africa, to the exclusion of Asian countries and the Congo.

CONCLUSION

This study shows that saliva harbours protein-coding bacterial genes that are geographically structured, and which could potentially be used for addressing previously unresolved human migration events.

Reconstructing Austronesian population history in Island Southeast Asia

Austronesian languages are spread across half the globe, from Easter Island to Madagascar. Evidence from linguistics and archaeology indicates that the ‘Austronesian expansion,’ which began 4,000–5,000 years ago, likely had roots in Taiwan, but the ancestry of present-day Austronesian-speaking populations remains controversial. Here, we analyse genome-wide data from 56 populations using new methods for tracing ancestral gene flow, focusing primarily on Island Southeast Asia. We show that all sampled Austronesian groups harbour ancestry that is more closely related to aboriginal Taiwanese than to any present-day mainland population. Surprisingly, western Island Southeast Asian populations have also inherited ancestry from a source nested within the variation of present-day populations speaking Austro-Asiatic languages, which have historically been nearly exclusive to the mainland. Thus, either there was once a substantial Austro-Asiatic presence in Island Southeast Asia, or Austronesian speakers migrated to and through the mainland, admixing there before continuing to western Indonesia.

Populations speaking Austronesian languages are numerous and widespread, but their history remains controversial. Here, the authors analyse genetic data from Southeast Asia and show that all populations harbour ancestry most closely related to aboriginal Taiwanese, while some also contain a component closest to Austro-Asiatic speakers.

Taiwan Y-chromosomal DNA variation and its relationship with Island Southeast Asia

Background

Much of the data resolution of the haploid non-recombining Y chromosome (NRY) haplogroup O in East Asia are still rudimentary and could be an explanatory factor for current debates on the settlement history of Island Southeast Asia (ISEA). Here, 81 slowly evolving markers (mostly SNPs) and 17 Y-chromosomal short tandem repeats were used to achieve higher level molecular resolution. Our aim is to investigate if the distribution of NRY DNA variation in Taiwan and ISEA is consistent with a single pre-Neolithic expansion scenario from Southeast China to all ISEA, or if it better fits an expansion model from Taiwan (the OOT model), or whether a more complex history of settlement and dispersals throughout ISEA should be envisioned.

Results

We examined DNA samples from 1658 individuals from Vietnam, Thailand, Fujian, Taiwan (Han, plain tribes and 14 indigenous groups), the Philippines and Indonesia. While haplogroups O1a*-M119, O1a1*-P203, O1a2-M50 and O3a2-P201 follow a decreasing cline from Taiwan towards Western Indonesia, O2a1-M95/M88, O3a*-M324, O3a1c-IMS-JST002611 and O3a2c1a-M133 decline northward from Western Indonesia towards Taiwan. Compared to the Taiwan plain tribe minority groups the Taiwanese Austronesian speaking groups show little genetic paternal contribution from Han. They are also characterized by low Y-chromosome diversity, thus testifying for fast drift in these populations. However, in contrast to data provided from other regions of the genome, Y-chromosome gene diversity in Taiwan mountain tribes significantly increases from North to South.

Conclusion

The geographic distribution and the diversity accumulated in the O1a*-M119, O1a1*-P203, O1a2-M50 and O3a2-P201 haplogroups on one hand, and in the O2a1-M95/M88, O3a*-M324, O3a1c-IMS-JST002611 and O3a2c1a-M133 haplogroups on the other, support a pincer model of dispersals and gene flow from the mainland to the islands which likely started during the late upper Paleolithic, 18,000 to 15,000 years ago. The branches of the pincer contributed separately to the paternal gene pool of the Philippines and conjointly to the gene pools of Madagascar and the Solomon Islands. The North to South increase in diversity found for Taiwanese Austronesian speaking groups contrasts with observations based on mitochondrial DNA, thus hinting to a differentiated demographic history of men and women in these populations.

Different gene preferences of maple syrup urine disease in the aboriginal tribes of Taiwan

BACKGROUND

Maple syrup urine disease (MSUD) is a rare inborn error of metabolism caused by a deficiency of the branched-chain α-ketoacid dehydrogenase (BCKD) complex. Mutations in any one of the three different genes encoding for the BCKD components, namely, BCKDHA, BCKDHB, and DBT, may be responsible for this disease. In Taiwan, few MSUD cases were diagnosed clinically, and most of these patients are from Aboriginal tribes.

MATERIALS AND METHODS

To identify and detect the carrier frequency of MSUD in Taiwanese Aboriginal tribes, we performed biochemical and molecular studies from peripheral blood in MSUD patients and dried blood on filter paper in the enrolled screened populations.

RESULTS

Homozygous A208T and I281T of BCKDHA were found in two patients from Hans (non-Aboriginal Taiwanese), respectively; compound heterozygous mutations of the DBT gene [4.7 kb deletion/c.650-651insT (L217F or L217fsX223) and c.650-651insT/c.88-89delAT] were found in two patients from Amis, respectively, after direct DNA sequencing and polymerase chain reaction-restriction fragment length polymorphism studies. There were no cases of deleted 4.7-kb heterozygote out of 302 normal people (Hans, n = 125; Atayal, n = 156; and Saisiyat, n = 21); by contrast, the DBT mutations c.650-651insT and deleted 4.7-kb heterozygote were noted in 2/121 and 1/121, respectively, from the general population of the Amis, a southeastern Taiwanese tribe.

CONCLUSION

Although the Taiwanese Austronesian Aboriginal tribes are considered to share a common origin, different gene preferences of MSUD were noted. The novel DBT mutation c.650-651insT was more prevalent than the deleted 4.7-kb heterozygote in the Amis population. The reported 4.7-kb deletion indicating a possible founder mutation may be preserved in the southern and eastern, but not in northern Aboriginal tribes of Taiwan.

Extreme genetic heterogeneity among the nine major tribal Taiwanese island populations detected with a new generation Y23 STR system

The Taiwanese aborigines have been regarded as the source populations for the Austronesian expansion that populated Oceania to the east and Madagascar off Africa to the West. Although a number of genetic studies have been performed on some of these important tribes, the scope of the investigations has been limited, varying in the specific populations examined as well as the maker systems employed. This has made direct comparison among studies difficult. In an attempt to alleviate this lacuna, we investigate, for the first time, the genetic diversity of all nine major Taiwanese aboriginal tribes (Ami, Atayal, Bunun, Rukai, Paiwan, Saisat, Puyuma, Tsou and Yami) utilizing a new generation multiplex Y-STR system that allows for the genotyping of 23 loci from a single amplification reaction. This comprehensive approach examining 293 individuals from all nine main tribes with the same battery of forensic markers provides for the much-needed equivalent data essential for comparative analyses. Our results have uncovered that these nine major aboriginal populations exhibit limited intrapopulation genetic diversity and are highly heterogeneous from each other, possibly the result of endogamy, isolation, drift and/or unique ancestral populations. Specifically, genetic diversity, discrimination capacity, fraction of unique haplotypes and the most frequent haplotypes differ among the nine tribes, with the Tsou possessing the lowest values for the first three of these parameters. The phylogenetic analyses performed indicate that the genetic diversity among all nine tribes is greater than the diversity observed among the worldwide reference populations examined, indicating an extreme case of genetic heterogeneity among these tribes that have lived as close neighbors for thousands of years confined to the limited geographical area of an island.

Maternal history of Oceania from complete mtDNA genomes: contrasting ancient diversity with recent homogenization due to the Austronesian expansion

Archaeology, linguistics, and existing genetic studies indicate that Oceania was settled by two major waves of migration. The first migration took place approximately 40 thousand years ago and these migrants, Papuans, colonized much of Near Oceania. Approximately 3.5 thousand years ago, a second expansion of Austronesian-speakers arrived in Near Oceania and the descendants of these people spread to the far corners of the Pacific, colonizing Remote Oceania. To assess the female contribution of these two human expansions to modern populations and to investigate the potential impact of other migrations, we obtained 1,331 whole mitochondrial genome sequences from 34 populations spanning both Near and Remote Oceania. Our results quantify the magnitude of the Austronesian expansion and demonstrate the homogenizing effect of this expansion on almost all studied populations. With regards to Papuan influence, autochthonous haplogroups support the hypothesis of a long history in Near Oceania, with some lineages suggesting a time depth of 60 thousand years, and offer insight into historical interpopulation dynamics. Santa Cruz, a population located in Remote Oceania, is an anomaly with extreme frequencies of autochthonous haplogroups of Near Oceanian origin; simulations to investigate whether this might reflect a pre-Austronesian versus Austronesian settlement of the island failed to provide unequivocal support for either scenario.

Mitochondrial DNA association study of type 2 diabetes with or without ischemic stroke in Taiwan

Background

The importance of mitochondrial DNA (mtDNA) polymorphism in the prediction of type 2 diabetes (T2D) in men and women is not well understood. We questioned whether mtDNA polymorphism, mitochondrial functions, age and gender influenced the occurrence of T2D with or without ischemic stroke (IS).

Methods

We first designed a matched case–control study of 373 T2D patients and 327 healthy unrelated individuals without history of IS. MtDNA haplogroups were determined on all participants using sequencing of the control region and relevant SNPs from the coding region. Mitochondria functional tests, systemic biochemical measurements and complete genomic mtDNA sequencing were further determined on 239 participants (73 healthy controls, 33 T2D with IS, 70 T2D only and 63 IS patients without T2D).

Results

MtDNA haplogroups B4a1a, and E2b1 showed significant association with T2D (P <0.05), and haplogroup D4 indicated resistance (P <0.05). Mitochondrial and systemic functional tests showed significantly less variance within groups bearing the same mtDNA haplotypes. There was a pronounced male excess among all T2D patients and prevalence of IS was seen only in the older population. Finally, nucleotide variant np 15746, a determinant of haplogroup G3 seen in Japanese and of B4a1a prevalent in Taiwanese was associated with T2D in both populations.

Conclusions

Men appeared more susceptible to T2D than women. Although the significant association of B4a1a and E2b1 with T2D ceased when corrected for multiple testings, these haplogroups are seen only among Taiwan Aborigines, Southeast Asian and the Pacific Ocean islanders where T2D is predominant. The data further suggested that physiological and biochemical measurements were influenced by the mtDNA genetic profile of the individual. More understanding of the function of the mitochondrion in the development of T2D might indicate ways of influencing the early course of the disease.

Human genetics of the Kula Ring: Y-chromosome and mitochondrial DNA variation in the Massim of Papua New Guinea

The island region at the southeastern-most tip of New Guinea and its inhabitants known as Massim are well known for a unique traditional inter-island trading system, called Kula or Kula Ring. To characterize the Massim genetically, and to evaluate the influence of the Kula Ring on patterns of human genetic variation, we analyzed paternally inherited Y-chromosome (NRY) and maternally inherited mitochondrial (mt) DNA polymorphisms in >400 individuals from this region. We found that the nearly exclusively Austronesian-speaking Massim people harbor genetic ancestry components of both Asian (AS) and Near Oceanian (NO) origin, with a proportionally larger NO NRY component versus a larger AS mtDNA component. This is similar to previous observations in other Austronesian-speaking populations from Near and Remote Oceania and suggests sex-biased genetic admixture between Asians and Near Oceanians before the occupation of Remote Oceania, in line with the Slow Boat from Asia hypothesis on the expansion of Austronesians into the Pacific. Contrary to linguistic expectations, Rossel Islanders, the only Papuan speakers of the Massim, showed a lower amount of NO genetic ancestry than their Austronesian-speaking Massim neighbors. For the islands traditionally involved in the Kula Ring, a significant correlation between inter-island travelling distances and genetic distances was observed for mtDNA, but not for NRY, suggesting more male- than female-mediated gene flow. As traditionally only males take part in the Kula voyages, this finding may indicate a genetic signature of the Kula Ring, serving as another example of how cultural tradition has shaped human genetic diversity.

Taiwanese aborigines: genetic heterogeneity and paternal contribution to Oceania

In the present study, for the first time, 293 Taiwanese aboriginal males from all nine major tribes (Ami, Atayal, Bunun, Rukai, Paiwan, Saisat, Puyuma, Tsou, Yami) were genotyped with 17 YSTR loci in a attend to reveal migrational patterns connected with the Austronesian expansion. We investigate the paternal genetic relationships of these Taiwanese aborigines to 42 Asia-Pacific reference populations, geographically selected to reflect various locations within the Austronesian domain. The Tsou and Puyuma tribes exhibit the lowest (0.1851) and the highest (0.5453) average total genetic diversity, respectively. Further, the fraction of unique haplotypes is also relatively high in the Puyuma (86.7%) and low in Tsou (33.3%) suggesting different demographic histories. Multidimensional scaling (MDS) and analysis of molecular variance (AMOVA) revealed several notable findings: 1) the Taiwan indigenous populations are highly diverse. In fact, the level of inter-population heterogeneity displayed by the Taiwanese aboriginal populations is close to that exhibited among all 51 Asia-Pacific populations examined; 2) the asymmetrical contribution of the Taiwanese aborigines to the Oceanic groups. Ami, Bunun and Saisiyat tribes exhibit the strongest paternal links to the Solomon and Polynesian island communities, whereas most of the remaining Taiwanese aboriginal groups are more genetically distant to these Oceanic inhabitants; 3) the present YSTR analyses does not reveal a strong paternal affinity of the nine Taiwanese tribes to their continental Asian neighbors. Overall, our current findings suggest that, perhaps, only a few of the tribes were involved in the migration out of Taiwan.

Early Austronesians: into and out of Taiwan

A Taiwan origin for the expansion of the Austronesian languages and their speakers is well supported by linguistic and archaeological evidence. However, human genetic evidence is more controversial. Until now, there had been no ancient skeletal evidence of a potential Austronesian-speaking ancestor prior to the Taiwan Neolithic ~6,000 years ago, and genetic studies have largely ignored the role of genetic diversity within Taiwan as well as the origins of Formosans. We address these issues via analysis of a complete mitochondrial DNA genome sequence of an ~8,000-year-old skeleton from Liang Island (located between China and Taiwan) and 550 mtDNA genome sequences from 8 aboriginal (highland) Formosan and 4 other Taiwanese groups. We show that the Liangdao Man mtDNA sequence is closest to Formosans, provides a link to southern China, and has the most ancestral haplogroup E sequence found among extant Austronesian speakers. Bayesian phylogenetic analysis allows us to reconstruct a history of early Austronesians arriving in Taiwan in the north ~6,000 years ago, spreading rapidly to the south, and leaving Taiwan ~4,000 years ago to spread throughout Island Southeast Asia, Madagascar, and Oceania.

Developmental validation of mitochondrial DNA genotyping assays for adept matrilineal inference of biogeographic ancestry at a continental level

Mitochondrial DNA (mtDNA) can be used for matrilineal biogeographic ancestry prediction and can thus provide investigative leads towards identifying unknown suspects, when conventional autosomal short tandem repeat (STR) profiling fails to provide a match. Recently, six multiplex genotyping assays targeting 62 ancestry-informative mitochondrial single nucleotide polymorphisms (mt-SNPs) were developed. This hierarchical system of assays allows detection of the major haplogroups present in Africa, America, Western Eurasia, Eastern Eurasia, Australia and Oceania, thus revealing the broad geographic region of matrilineal origin of a DNA donor. Here, we provide a forensic developmental validation study of five multiplex assays targeting all the 62 ancestry-informative mt-SNPs following the Scientific Working Group on DNA Analysis Methods (SWGDAM) guidelines. We demonstrate that the assays are highly sensitive; being able to produce full profiles at input DNA amounts of as little as 1pg. The assays were shown to be highly robust and efficient in providing information from degraded samples and from simulated casework samples of different substrates such as blood, semen, hair, saliva and trace DNA samples. Reproducible results were successfully achieved from concordance testing across three independent laboratories depicting the ease and reliability of these assays. Overall, our results demonstrate the suitability of these five mt-SNP assays for application to forensic casework and other purposes aiming to establish an individual's matrilineal genetic ancestry. With this validated tool, it is now possible to determine the matrilineal biogeographic origin of unknown individuals on the level of continental resolution from forensic DNA samples to provide investigative leads in criminal and missing person cases where autosomal STR profiling is uninformative.

Genetic diversity of four Filipino negrito populations from Luzon: comparison of male and female effective population sizes and differential integration of immigrants into Aeta and Agta communities

Genetic data corresponding to four negrito populations (two Aeta and two Agta; n = 120) from the Luzon region of the Philippines have been analyzed. These data comprise mitochondrial DNA (mtDNA) hypervariable segment 1 haplotypes and haplogroups, Y-chromosome haplogroups and short tandem repeats (STRs), autosomal STRs, and X-chromosome STRs. The genetic diversity and structure of the populations were investigated at a local, regional, and interregional level. We found a high level of autosomal differentiation, combined with no significant reduction in diversity, consistent with long-term settlement of the Luzon region by the ancestors of the Agta and Aeta followed by reduced gene flow between these two ethnolinguistic groups. Collectively, the Aeta have a much higher ratio of female:male effective population size than do the Agta, a finding that supports phylogenetic analysis of their mtDNA and Y-chromosome haplogroups, which suggests different genetic sex-biased contributions from putative Austronesian source populations. We propose that factors of social organization that led to the reduction in Agta female effective population size may also be linked to the limited incorporation of female lineages associated with the settlement of the Philippines by Austronesian speakers; conversely, the reduction in Aeta male effective population size, relative to females, could be indicative of a limited incorporation of male lineages associated with this demographic process.

Correlations in the population structure of music, genes and language

We present, to our knowledge, the first quantitative evidence that music and genes may have coevolved by demonstrating significant correlations between traditional group-level folk songs and mitochondrial DNA variation among nine indigenous populations of Taiwan. These correlations were of comparable magnitude to those between language and genes for the same populations, although music and language were not significantly correlated with one another. An examination of population structure for genetics showed stronger parallels to music than to language. Overall, the results suggest that music might have a sufficient time-depth to retrace ancient population movements and, additionally, that it might be capturing different aspects of population history than language. Music may therefore have the potential to serve as a novel marker of human migrations to complement genes, language and other markers.

Associations of mitochondrial haplogroups b4 and e with biliary atresia and differential susceptibility to hydrophobic bile Acid

Mitochondrial dysfunction has been implicated in the pathogenesis of biliary atresia (BA). This study aimed to determine whether a specific mitochondrial DNA haplogroup is implicated in the pathogenesis and prognosis of BA. We determined 40 mitochondrial single nucleotide polymorphisms in 15 major mitochondrial haplogroups by the use of 24-plex PCR and fluorescent beads combined with sequence-specific oligonucleotide probes in 71 patients with BA and in 200 controls in the Taiwanese population of ethnic Chinese background. The haplogroup B4 and E prevalence were significantly lower and higher respectively, in the patients with BA than in the controls (odds ratios, 0.82 [p = 0.007] and 7.36 [p = 0.032] respectively) in multivariate logistic-regression analysis. The 3-year survival rate with native liver was significantly lower in haplogroup E than the other haplogroups (P = 0.037). A cytoplasmic hybrid (cybrid) was obtained from human 143B osteosarcoma cells devoid of mtDNA (ρ⁰ cell) and was fused with specific mtDNA bearing E and B4 haplogroups donated by healthy Taiwanese subjects. Chenodeoxycholic acid treatment resulted in significantly lower free radical production, higher mitochondrial membrane potential, more viable cells, and fewer apoptotic cybrid B4 cells than parental 143B and cybrid E cells. Bile acid treatment resulted in a significantly greater protective mitochondrial reaction with significantly higher mitochondrial DNA copy number and mitofusin 1 and 2 concentrations in cybrid B4 and parental cells than in cybrid E cells. The results of the study suggested that the specific mitochondrial DNA haplogroups B4 and E were not only associated with lower and higher prevalence of BA respectively, in the study population, but also with differential susceptibility to hydrophobic bile acid in the cybrid harboring different haplogroups.

Mitochondrial dysfunction has been implicated in the pathogenesis of biliary atresia (BA). We determined 40 mitochondrial single nucleotide polymorphisms in different mitochondrial haplogroups in BA patients and controls. The prevalence of haplogroup B4 and E was significantly lower and higher respectively, in the patients with BA than in the controls. The survival rate with native liver was significantly lower in haplogroup E than the other haplogroups. The in vitro study using cybrid cells revealed significantly lower free radical production, higher mitochondrial membrane potential, higher mitochondrial DNA copy number and fewer apoptotic in cybrid B4 cells than cybrid E cells. The study provides a novel insight into the etiopathogenesis and the predictive value of mitochondrial haplogroups in BA.

Complete mtDNA genomes of Filipino ethnolinguistic groups: a melting pot of recent and ancient lineages in the Asia-Pacific region

The Philippines is a strategic point in the Asia-Pacific region for the study of human diversity, history and origins, as it is a cross-road for human migrations and consequently exhibits enormous ethnolinguistic diversity. Following on a previous in-depth study of Y-chromosome variation, here we provide new insights into the maternal genetic history of Filipino ethnolinguistic groups by surveying complete mitochondrial DNA (mtDNA) genomes from a total of 14 groups (11 groups in this study and 3 groups previously published) including previously published mtDNA hypervariable segment (HVS) data from Filipino regional center groups. Comparison of HVS data indicate genetic differences between ethnolinguistic and regional center groups. The complete mtDNA genomes of 14 ethnolinguistic groups reveal genetic aspects consistent with the Y-chromosome, namely: diversity and heterogeneity of groups, no support for a simple dichotomy between Negrito and non-Negrito groups, and different genetic affinities with Asia-Pacific groups that are both ancient and recent. Although some mtDNA haplogroups can be associated with the Austronesian expansion, there are others that associate with South Asia, Near Oceania and Australia that are consistent with a southern migration route for ethnolinguistic group ancestors into the Asia-Pacific, with a timeline that overlaps with the initial colonization of the Asia-Pacific region, the initial colonization of the Philippines and a possible separate post-colonization migration into the Philippine archipelago.

Identification of Polynesian mtDNA haplogroups in remains of Botocudo Amerindians from Brazil

There is a consensus that modern humans arrived in the Americas 15,000-20,000 y ago during the Late Pleistocene, most probably from northeast Asia through Beringia. However, there is still debate about the time of entry and number of migratory waves, including apparent inconsistencies between genetic and morphological data on Paleoamericans. Here we report the identification of mitochondrial sequences belonging to haplogroups characteristic of Polynesians in DNA extracted from ancient skulls of the now extinct Botocudo Indians from Brazil. The identification of these two Polynesian haplogroups was confirmed in independent replications in Brazil and Denmark, ensuring reliability of the data. Parallel analysis of 12 other Botocudo individuals yielded only the well-known Amerindian mtDNA haplogroup C1. Potential scenarios to try to help understand these results are presented and discussed. The findings of this study may be relevant for the understanding of the pre-Columbian and/or post-Columbian peopling of the Americas.

Ascertaining the role of Taiwan as a source for the Austronesian expansion

Taiwanese aborigines have been deemed the ancestors of Austronesian speakers which are currently distributed throughout two-thirds of the globe. As such, understanding their genetic distribution and diversity as well as their relationship to mainland Asian groups is important to consolidating the numerous models that have been proposed to explain the dispersal of Austronesian speaking peoples into Oceania. To better understand the role played by the aboriginal Taiwanese in this diaspora, we have analyzed a total of 451 individuals belonging to nine of the tribes currently residing in Taiwan, namely the Ami, Atayal, Bunun, Paiwan, Puyuma, Rukai, Saisiyat, Tsou, and the Yami from Orchid Island off the coast of Taiwan across 15 autosomal short tandem repeat loci. In addition, we have compared the genetic profiles of these tribes to populations from mainland China as well as to collections at key points throughout the Austronesian domain. While our results suggest that Daic populations from Southern China are the likely forefathers of the Taiwanese aborigines, populations within Taiwan show a greater genetic impact on groups at the extremes of the current domain than populations from Indonesia, Mainland, or Southeast Asia lending support to the "Out of Taiwan" hypothesis. We have also observed that specific Taiwanese aboriginal groups (Paiwan, Puyuma, and Saisiyat), and not all tribal populations, have highly influenced genetic distributions of Austronesian populations in the pacific and Madagascar suggesting either an asymmetric migration out of Taiwan or the loss of certain genetic signatures in some of the Taiwanese tribes due to endogamy, isolation, and/or drift.

A highly unstable recent mutation in human mtDNA

An A-to-G transition at position 16247 in the human mtDNA genome denotes haplogroup B4a1a1a and its sublineages. Informally known as the "Polynesian motif," this haplogroup has been widely used as a marker in Oceania of genetic affiliation with the Austronesian expansion. The 16247G allele has arisen only once in the human mtDNA phylogeny, about 7,000 thousand years ago, and is nearly fixed in Remote Oceania. We analyzed 536 complete mtDNA genome sequences from the Solomon Islands from haplogroup B4a1a1 and associated subhaplogroups and found multiple independent back mutations from 16247G to 16247A. We also find elevated levels of heteroplasmy at this position in samples with the 16247G allele, suggesting the ongoing occurrence of somatic back-mutations and/or transmission of heteroplasmy. Moreover, the G allele is predicted to introduce a novel stem-loop structure in the DNA sequence that may be structurally unfavorable, thereby accounting for the remarkable number of back-mutations observed at the 16247G allele in this short evolutionary time span. More generally, haplogroup-calling scripts result in inaccurate haplogroup calls involving the back-mutation and need to be supplemented with other types of analyses; this may be true for other mtDNA lineages because no other lineage has been investigated to the same extent (over 500 complete mtDNA sequences).

Y-chromosome and mtDNA genetics reveal significant contrasts in affinities of modern Middle Eastern populations with European and African populations

The Middle East was a funnel of human expansion out of Africa, a staging area for the Neolithic Agricultural Revolution, and the home to some of the earliest world empires. Post LGM expansions into the region and subsequent population movements created a striking genetic mosaic with distinct sex-based genetic differentiation. While prior studies have examined the mtDNA and Y-chromosome contrast in focal populations in the Middle East, none have undertaken a broad-spectrum survey including North and sub-Saharan Africa, Europe, and Middle Eastern populations. In this study 5,174 mtDNA and 4,658 Y-chromosome samples were investigated using PCA, MDS, mean-linkage clustering, AMOVA, and Fisher exact tests of F_ST's, R_ST's, and haplogroup frequencies. Geographic differentiation in affinities of Middle Eastern populations with Africa and Europe showed distinct contrasts between mtDNA and Y-chromosome data. Specifically, Lebanon's mtDNA shows a very strong association to Europe, while Yemen shows very strong affinity with Egypt and North and East Africa. Previous Y-chromosome results showed a Levantine coastal-inland contrast marked by J1 and J2, and a very strong North African component was evident throughout the Middle East. Neither of these patterns were observed in the mtDNA. While J2 has penetrated into Europe, the pattern of Y-chromosome diversity in Lebanon does not show the widespread affinities with Europe indicated by the mtDNA data. Lastly, while each population shows evidence of connections with expansions that now define the Middle East, Africa, and Europe, many of the populations in the Middle East show distinctive mtDNA and Y-haplogroup characteristics that indicate long standing settlement with relatively little impact from and movement into other populations.