HGM2002 Poster Abstracts: 11. Genome Diversity
POSTER NO: 573
Mitochondrial DNA phylogeography and population history of West, South and Central Asia
1L. Quintana-Murci, 2S. Wells, 3R. Chaix, 4H. Sayar, 1C. Ottolenghi, 5Q. Ayub, 6C. Tyler-Smith, 5S.Q. Mehdi, 7H.J. Bandelt, 1K. McElreavey
Mitochondrial DNA (mtDNA) sequence variation was examined in 702 individuals from 20 different Asian populations by hypervariable segment I (HVS-I) sequencing and restriction analysis of diagnostic haplogroup-specific sites. Populations analysed included 6 ethnic groups from Iran (Gilak, Mazandarians, Kurds, Turks, Persian and Lurs), 9 from Pakistan (Hazara, Hunza, Kalash Kafirs, Sindhi, Brahui, Makrani Negroid, Pathans and Parsi), 4 from Central Asia (Turkmen, Turkmen Kurds, Uzbek and Pamiris) and one population from north-west India (Gujurat). Globally, populations in the south and coastal regions exhibited a different pattern of haplogroup (Hg) distribution from those living in the north and Central Asia. Southern populations are characterised by high frequencies of both Hg M, (which may trace a coastal route of exit of modern humans from East-Africa towards India), and the Indian subclade of Hg U2 (U2i). Populations living in the northern regions of Pakistan and Central Asia are characterised by both East-Asian lineages (A, B, C, D), and Western Eurasian lineages (Hgs H, HV and pre-HV). This north/south differential Hg distribution suggests different peopling processes along the coastal range of south Asia and the region located along the Silk Road. Population-specific, distinct Hg frequencies are particularly evident in some ethnic groups. In the Hazaras, historically considered to be descendants of Genghis Khan's soldiers, a substantial fraction of East-Asian specific lineages is observed, while in the Kalash Kafirs, who claim descent from Greeks and some anthropologists assign a Slave origin to this population, most lineages fall into common western Eurasian Hgs (HV, U4 and U2e). Interestingly, this latter lineage is the European-specific subclade of Hg U2. The Negroid Makrani from the southern coast of Pakistan deserves special consideration. Our data shows that more than 40% of Makrani mtDNAs is attributable to influx of maternal lineages from Africa (including L1a (4%), L2 (9%), L3b (9%) and L3d (18%)). These African Hgs were found to be virtually absent in all the other populations examined. Sequence matching analysis suggests that the African mtDNA component present in the current Makrani gene pool is of recent origin. This pattern of mtDNA distribution is compatible with the documented slave trade from Central/East Africa, via the Arabian peninsula, towards South Asia, rather than ancient migrations of modern humans into south Asia. These results contrast with the Y-chromosome data set in this population which shows that they are undifferentiated from the other Pakistani ethnic groups and distinct from African populations. The study of the modern Makrani gene pool suggests significant directional mating between local males and females related to Bantu-speaking populations from sub-Saharan Africa. These data demonstrates how mtDNA diversity can be used to reconstruct population histories and reveal traces of past population movements over wide geographic areas.
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