HGM2002 Poster Abstracts: 11. Genome Diversity



Investigation of the Greek ancestry of northern Pakistani ethnic groups using Y chromosomal DNA variation

1Q. Ayub, 1A. Mansoor, 1A. Mohyuddin, 1K. Mazhar, 1S. Siddiqi, 2M. Papaioannou, 3C. Tyler-Smith, 1S.Q. Mehdi
1Biomedical and Genetic Engineering Division, Dr. A.Q. Khan Research Laboratories, P.O. Box 2891, Islamabad 44000, Pakistan, 2Unit of Prenatal Diagnosis, Center for Thalassemia, Laiko General Hospital, Athens, Greece, 3CRC Chromosome Molecular Biology Group, Department of Biochemistry, University of oxford, Oxford, UK

Pakistan lies in a region that has witnessed multiple invasions and migrations over the centuries. Alexander the Great invaded the Indian sub-continent in 327-325 B.C. and three northern Pakistani populations, the Burusho, the Kalash and the Pathan claim descent from Greek soldiers who were left behind in this region. The Burusho reside in the Hunza and Nagar valleys, which are located in the Karakorum Mountains and speak the language isolate Burushaski. The Kalash have been isolated for centuries in the Hindu Kush mountain ranges of northern Pakistan and speak Kalasha, an Indo-European language. The Pathan tribes inhabit the North West Frontier Province of Pakistan and the southern and eastern parts of neighboring Afghanistan. They speak Pushto, also an Indo-European language. To investigate the male-line genetic relationship between the extant Greek population (assuming that modern Greek are representative of Alexander's armies) and the three Pakistani ethnic groups, 16 binary unique event polymorphisms, and 16 multiallelic, short-tandem-repeat (STR) loci, mapping on the non-recombining portion of the human Y chromosome were typed in 910 individuals. The combination of the biallelic markers identified 7 stable Y chromosomal lineages in the Greek, Burusho and Pathan populations and 5 in the Kalash. Haplogroups 1, 2, 3 and 9 were present in all four populations. The M20 A to G transition (haplogroup 28) was found in all three Pakistani populations but was absent in the Greeks. This polymorphism probably originated in or near Pakistan as it has not been found at a significant frequency except in this area. Haplogroup 21 was frequent in the Greeks but in these Pakistani populations was found only in the Pathans. Based upon haplogroup frequencies, 65-88% Greek admixture was estimated for the Kalash, consistent with a Greek origin for a significant proportion of Kalash Y chomosomes. However, the Kalash lack haplogroup 21 chromosomes and appeared distinct from the Greeks based upon principal components analysis of haplogroup frequencies and weighted population pairwise FST values based on STR variation within Y Haplogroups. They clearly contain a substantial proportion of Pakistani Y chromosomes, illustrated by their high frequency of hg 28, and the true Greek contribution remains uncertain. Estimates of Greek Y admixture for the Pathans were about 10%, and for the Burusho were close to zero. Median-joining networks of STR haplotypes revealed considerable sub-structuring of Y variation within the Kalash and Burusho, and in particular the haplogroup 21 network showed that the Pathan chromosomes were closely related to the central Greek cluster. Thus a small Greek contribution to the Pathans seems likely, the contribution to the Kalash is unclear and no contribution to the Burusho could be detected.


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