Contrasting maternal and paternal genetic variation of hunter-gatherer groups in Thailand.

The Maniq and Mlabri are the only recorded nomadic hunter-gatherer groups in Thailand. Here, we sequenced complete mitochondrial (mt) DNA genomes and ~2.364 Mbp of non-recombining Y chromosome (NRY) to learn more about the origins of these two enigmatic populations.

Y chromosomal evidence on the origin of northern Thai people.

The Khon Mueang represent the major group of people present in today's northern Thailand. While linguistic and genetic data seem to support a shared ancestry between Khon Mueang and other Tai-Kadai speaking people, the possibility of an admixed origin with contribution from local Mon-Khmer population could not be ruled out. Previous studies conducted on northern Thai people did not provide a definitive answer and, in addition, have largely overlooked the distribution of paternal lineages in the area.

A comprehensive ethnic-based analysis of alpha thalassaemia allelle frequency in northern Thailand.

Alpha (α)-thalassaemia is one of the most prevalent hereditary blood disorders, commonly affecting Southeast Asian people, with the highest incidence (30-40%) being seen in northern Thailand. However, this high incidence was estimated without consideration of the variations between ethnic populations and the geographical location of the populations. To address this issue, a total of 688 samples from 13 different northern Thai ethnic groups (30 villages) categorized into three linguistic groups were genotyped for deletional alpha-thalassaemia (-α, -α, -- and --) and/or non-deletional alpha-thalassaemia (α and α) via multiplex gap-PCR and dot-blot hybridization, respectively.

Endogamous marriage and the prevalence of hemoglobin E in ethnic groups of northern Thailand.

Objective: To investigate the impact of the endogamous marriage culture on the prevalence of the hemoglobin E (HbE) recessive variant.

Methods: The prevalence of the hemoglobin E (HbE) recessive variant was determined by dot-blot hybridization in 4 endogamous villages (1 Mlabri and 3 Htin ethnic groups) in comparison with 9 other nearby non-endogamous populations.

Results: Although the overall HbE prevalence in the population studied (8.

Complete mitochondrial genomes of Thai and Lao populations indicate an ancient origin of Austroasiatic groups and demic diffusion in the spread of Tai-Kadai languages.

The Tai-Kadai (TK) language family is thought to have originated in southern China and spread to Thailand and Laos, but it is not clear if TK languages spread by demic diffusion (i.e., a migration of people from southern China) or by cultural diffusion, with native Austroasiatic (AA) speakers switching to TK languages.

Correction: Hemoglobin E Prevalence among Ethnic Groups Residing in Malaria-Endemic Areas of Northern Thailand and Its Lack of Association with Plasmodium falciparum Invasion In Vitro.

[This corrects the article DOI: 10.1371/journal.pone.

Effect of migration patterns on maternal genetic structure: a case of Tai-Kadai migration from China to Thailand.

The migration of the Tai-Kadai speaking people from southern China to northern Thailand over the past hundreds of years has revealed numerous patterns that have likely been influenced by routes, purposes and periods of time. To study the effects of different migration patterns on Tai-Kadai maternal genetic structure, mitochondrial DNA hypervariable region I sequences from the Yong and the Lue people having well-documented histories in northern Thailand were analyzed. Although the Yong and Lue people were historically close relatives who shared Xishuangbanna Dai ancestors, significant genetic differences have been observed among them.

The prevalence of alpha-thalassemia amongst Tai and Mon-Khmer ethnic groups residing in northern Thailand: A population-based study.

Background: Northern Thailand is one of the highest α-thalassemia incidence areas where 30-40% of inhabitants have been reported to carry aberrant α-globin genes. However, all previous α-thalassemia prevalence surveys in northern Thailand have been undertaken without consideration of ethnicity. Here we report the prevalence of α-thalassemia genes in 4 Tai (Yong, Yuan, Khuen, Lue) and 4 Mon-Khmer speaking populations (Blang, Mon, Paluang, Lawa).

Hemoglobin E Prevalence among Ethnic Groups Residing in Malaria-Endemic Areas of Northern Thailand and Its Lack of Association with Plasmodium falciparum Invasion In Vitro.

Hemoglobin E (HbE) is one of the most common hemoglobin variants caused by a mutation in the β-globin gene, and found at high frequencies in various Southeast Asian groups. We surveyed HbE prevalence among 8 ethnic groups residing in 5 villages selected for their high period malaria endemicity, and 5 for low endemicity in northern Thailand, in order to uncover factors which may affect genetic persistence of HbE in these groups. We found the overall HbE prevalence 6.

Y-chromosome diversity suggests southern origin and Paleolithic backwave migration of Austro-Asiatic speakers from eastern Asia to the Indian subcontinent.

Analyses of an Asian-specific Y-chromosome lineage (O2a1-M95)--the dominant paternal lineage in Austro-Asiatic (AA) speaking populations, who are found on both sides of the Bay of Bengal--led to two competing hypothesis of this group's geographic origin and migratory routes. One hypothesis posits the origin of the AA speakers in India and an eastward dispersal to Southeast Asia, while the other places an origin in Southeast Asia with westward dispersal to India. Here, we collected samples of AA-speaking populations from mainland Southeast Asia (MSEA) and southern China, and genotyped 16 Y-STRs of 343 males who belong to the O2a1-M95 lineage.

Admixed origin of the Kayah (Red Karen) in Northern Thailand revealed by biparental and paternal markers.

This study analyzes the autosomal short tandem repeats (STRs) variation and the presence of Y chromosomal haplogroups from 44 individuals of the Kayah or Red Karen (KA) in Northern Thailand. The results based on autosomal STRs indicated that the KA exhibited closer genetic relatedness to populations from adjacent regions in Southeast Asia (SEA) than populations from Northeast Asia (NEA) and Tibet. Moreover, an admixed origin of the KA forming three population groups was observed: NEA, Southern China, and Northern Thailand.

Geography has more influence than language on maternal genetic structure of various northeastern Thai ethnicities.

Several literatures have shown the influence of geographic and linguistic factors in shaping genetic variation patterns, but their relative impact, if any, in the very heterogeneous northeastern region of Thailand has not yet been studied. This area, called Isan, is geographically structured in two wide basins, the Sakon Nakorn Basin and the Korat Basin, serving today as home to diverse ethnicities encompassing two different linguistic families, that is, the Austro-Asiatic; Suay (Kui), Mon, Chaobon (Nyahkur), So and Khmer, and the Tai-Kadai; Saek, Nyaw, Phu Tai, Kaleung and Lao Isan. In this study, we evaluated the relative role of geographic distance and barriers as well as linguistic differences as possible causes affecting the maternal genetic distances among northeastern Thai ethnicities.

An updated phylogeny of the human Y-chromosome lineage O2a-M95 with novel SNPs.

Though the Y-chromosome O2a-M95 lineage is one of the major haplogroups present in eastern Asian populations, especially among Austro-Asiatic speaking populations from Southwestern China and mainland Southeast Asia, to date its phylogeny lacks structure due to only one downstream SNP marker (M88) assigned to the lineage. A recent array-capture-based Y chromosome sequencing of Asian samples has yielded a variety of novel SNPs purportedly belonging to the O2a-M95 lineage, but their phylogenetic positions have yet to be determined. In this study, we sampled 646 unrelated males from 22 Austro-Asiatic speaking populations from Cambodia, Thailand and Southwestern China, and genotyped 12 SNP makers among the sampled populations, including 10 of the newly reported markers.

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

Background: The Mon-Khmer speaking peoples inhabited northern Thailand before the arrival of the Tai speaking people from southern China in the thirteenth century A.D. Historical and anthropological evidence suggests a close relationship between the Mon-Khmer groups and the present day majority northern Thai groups.

Genetic affinity and admixture of northern Thai people along their migration route in northern Thailand: evidence from autosomal STR loci.

The Khon Mueang (KM) are the largest group of northern Thai people. Our previous mtDNA studies have suggested an admixture process among the KM with the earlier Mon-Khmer-speaking inhabitants of this region. In this study, we evaluate genetic affinities and admixture among 10 KM populations in northern Thailand lying along the historical Yuan migration route, and 10 neighboring populations belonging to 7 additional ethnic groups: Lawa, Mon (Mon-Khmer-speaking groups), Shan, Yuan, Lue, Khuen and Yong (Tai-speaking groups) by analyzing 15 hypervariable autosomal short tandem repeat loci.

Genetic evidence supports linguistic affinity of Mlabri--a hunter-gatherer group in Thailand.

Background: The Mlabri are a group of nomadic hunter-gatherers inhabiting the rural highlands of Thailand. Little is known about the origins of the Mlabri and linguistic evidence suggests that the present-day Mlabri language most likely arose from Tin, a Khmuic language in the Austro-Asiatic language family. This study aims to examine whether the genetic affinity of the Mlabri is consistent with this linguistic relationship, and to further explore the origins of this enigmatic population.

Mapping human genetic diversity in Asia.

Asia harbors substantial cultural and linguistic diversity, but the geographic structure of genetic variation across the continent remains enigmatic. Here we report a large-scale survey of autosomal variation from a broad geographic sample of Asian human populations. Our results show that genetic ancestry is strongly correlated with linguistic affiliations as well as geography.

TP53 gene mutations of lung cancer patients in upper northern Thailand and environmental risk factors.

TP53 mutations are observed in about 40-70% of lung cancer tissues, and the hot spot codon mutations are in exons 5 through 8. Previous studies revealed that the distinct TP53 mutational pattern between population groups may be due to different racial or exogenous factors. This research aims to identify risk factors that influence TP53 gene mutation in lung cancer patients residing areas with high lung cancer incidence, in the upper northern part of Thailand.

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

Background: Ethnic minorities in Northern Thailand, often referred to as Hill Tribes, are considered an ideal model to study the different genetic impact of sex-specific migration rates expected in matrilocal (women remain in their natal villages after the marriage and men move to their wife's village) and patrilocal societies (the opposite is true). Previous studies identified such differences, but little is known about the possible interaction with another cultural factor that may potentially affect genetic diversity, i.e.

A biological evaluation of DNA damage detected by comet assay in healthy populations residing in areas that differ in lung cancer incidence.

The comet assay was performed to evaluate the effect of environmental exposure between human populations residing in two areas that differ in lung cancer incidence, Saraphi (n = 91) and Chom Thong (n = 94). Three parameters, the tail length, tail intensity, and tail moment, were used to detect DNA damage in peripheral blood and stimulated lymphocytes with and without the DNA repair inhibitor, aphidicolin. Internal standards, cryopreserved isolated lymphocytes, and isolated lymphocytes irradiated with 2 Gy gamma rays, were used to correct the interexperimental variability.

A comparative biomonitoring study of populations residing in regions with low and high risk of lung cancer using the chromosome aberration and the micronucleus tests.

Chromosome aberration (CA) and micronucleus (MN) tests were performed in peripheral blood lymphocytes from people residing in two districts of Chiang Mai, Thailand, a high-risk area, Saraphi (n=107), where the lung cancer incidence is three-fold higher than in a low-risk area, Chom Thong (n=118). The percentage of cells with CAs was significantly lower in the Saraphi population than in the Chom Thong population (0.47+/-0.

Y chromosome haplotypes reveal prehistorical migrations to the Himalayas.

By using 19 Y chromosome biallelic markers and 3 Y chromosome microsatellite markers, we analyzed the genetic structure of 31 indigenous Sino-Tibetan speaking populations (607 individuals) currently residing in East, Southeast, and South Asia. Our results showed that a T to C mutation at locus M122 is highly prevalent in almost all of the Sino-Tibetan populations, implying a strong genetic affinity among populations in the same language family. Furthermore, the extremely high frequency of H8, a haplotype derived from M122C, in the Sino-Tibetan speaking populations in the Himalayas including Tibet and northeast India indicated a strong bottleneck effect that occurred during a westward and then southward migration of the founding population of Tibeto-Burmans.