title: Mitochondrial and Y-chromosome diversity of the Tharus (Nepal): a reservoir of genetic variation.
abstract: BACKGROUND
  Central Asia and the Indian subcontinent represent an area considered as a source and a reservoir for human genetic diversity, with many markers taking root here, most of which are the ancestral state of eastern and western haplogroups, while others are local. Between these two regions, Terai (Nepal) is a pivotal passageway allowing, in different times, multiple population interactions, although because of its highly malarial environment, it was scarcely inhabited until a few decades ago, when malaria was eradicated. One of the oldest and the largest indigenous people of Terai is represented by the malaria resistant Tharus, whose gene pool could still retain traces of ancient complex interactions. Until now, however, investigations on their genetic structure have been scarce mainly identifying East Asian signatures.
  
  
  RESULTS
  High-resolution analyses of mitochondrial-DNA (including 34 complete sequences) and Y-chromosome (67 SNPs and 12 STRs) variations carried out in 173 Tharus (two groups from Central and one from Eastern Terai), and 104 Indians (Hindus from Terai and New Delhi and tribals from Andhra Pradesh) allowed the identification of three principal components: East Asian, West Eurasian and Indian, the last including both local and inter-regional sub-components, at least for the Y chromosome.
  
  
  CONCLUSIONS
  Although remarkable quantitative and qualitative differences appear among the various population groups and also between sexes within the same group, many mitochondrial-DNA and Y-chromosome lineages are shared or derived from ancient Indian haplogroups, thus revealing a deep shared ancestry between Tharus and Indians. Interestingly, the local Y-chromosome Indian component observed in the Andhra-Pradesh tribals is present in all Tharu groups, whereas the inter-regional component strongly prevails in the two Hindu samples and other Nepalese populations.The complete sequencing of mtDNAs from unresolved haplogroups also provided informative markers that greatly improved the mtDNA phylogeny and allowed the identification of ancient relationships between Tharus and Malaysia, the Andaman Islands and Japan as well as between India and North and East Africa. Overall, this study gives a paradigmatic example of the importance of genetic isolates in revealing variants not easily detectable in the general population.
authors: Dipartimento di Genetica e Microbiologia, Università di Pavia,Pavia, Italy. fornarin@pasteur.fr
authors: Simona
authors: S
authors: Fornarino
authors: Maria
authors: M
authors: Pala
authors: Vincenza
authors: V
authors: Battaglia
authors: Ramona
authors: R
authors: Maranta
authors: Alessandro
authors: A
authors: Achilli
authors: Guido
authors: G
authors: Modiano
authors: Antonio
authors: A
authors: Torroni
authors: Ornella
authors: O
authors: Semino
authors: Silvana A
authors: SA
authors: Santachiara-Benerecetti
mesh_terms: D044466:Asian People / Q000235:genetics; D041322:Chromosomes, Human, Y / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics*; D014644:Genetic Variation; D005828:Genetics, Population; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats; D009390:Nepal; D010802:Phylogeny; D025341:Principal Component Analysis; D017422:Sequence Analysis, DNA
chemical_list: D004272:DNA, Mitochondrial