mtDNA in West Eurasia

mtDNA in West Eurasia

Phylogeography of mitochondrial DNA in West Eurasia

Today’s West Eurasian genetic population structure is the result of several migration events that originated somewhere between East Africa and the Persian Gulf ~45,000 years ago [Torroni 2006]. Two major movements of humans took place during the Upper Palaeolithic before and after the Last Glacial Maximum (LGM). The Franco-Cantabrian refuge area of south-western Europe was the source of a late-glacial expansion of hunter-gatherers that repopulated northern Europe after the LGM [Achilli 2004].

More than three-quarters of the present-day European mtDNA gene pool most likely comes from indigenous Mesolithic or Palaeolithic ancestors. In addition Neolithic immigrants, who brought the first forms of agriculture to the hunter-gatherer dominated European landscape, ~8,000 years ago play an important part of today’s mtDNA pool of modern humans in West Eurasia [Richards 2000].

According to our current knowledge all non-Africans descend from two haplogroups (M and N) that derived from the African haplogroup L3. One branch (M) moved to East Asia, whereas the sister clade N spread into the Near East and Europe subsequently. Haplogroup N diverged further to give rise to haplogroup R, which is the founder of most West-Eurasian mtDNA lineages. Three R branches (haplogroups R0, JT and U) and additionally three minor N branches (N1, N2, X) are found in the present European mtDNA pool. Thus Europeans and Near Easterners share a rather recent common ancestry, since they share essentially the same set of haplogroups. Nearly half of the West Eurasian assemblage of human mtDNA is fractioned into numerous sub-lineages of the predominant haplogroup R0 (R0a, HV). Subhaplogroup H, descending from R0, is dominating with a considerable proportion of 40%-50% of all mtDNAs and can be further dissected into numerous sub-haplogroups.

Simplified European mtDNA haplogroup chart

Haplogroup V, a sister clade of H, can be found in Northern Scandinavia at a very high ratio (~60%) [Kivisild 2003]. Haplogroup U has an extremely broad geographic distribution that ranges from Europe and North Africa to India and Central Asia and has a very high overall frequency (15%-30%). This haplogroup arose shortly after the “out of Africa” exit and rapidly radiated into numerous distinct subclades (U1-U9) [Achilli 2005]. One of this subclades, haplogroup K (derived from haplogroup U8) is present all over Europe, but very prominent in Ashkenazi populations [Behar 2006]. One famous European, the “iceman” from the Austro-Italian Alps is a member of haplogroup K. Haplogroup J shows a greater genetic variability in the Middle East compared to Europe. Haplogroup T is present in about 20% of the mtDNA pool in West Eurasia. Also here we know one intriguing haplogroup T member Tsar Nicholas II of Russia.

To understand the distribution of present-day’s European haplogroups and provide a basis for frequency estimation European mtDNA haplotypes are analysed in population studies and stored and provided to the community in EMPOP.

Literature cited

Torroni A 2006 Trends Genet 22: 339-345
Achilli A 2004 Am J Hum Genet 75: 910-918
Richards M 2000 Am J Hum Genet 67: 1251-1276
Ingman M 2007 Eur J Hum Genet 15: 115-120
Kivisild T 2003 Am J Hum Genet 72: 313-332
Quintana-Murci L 2004 Am J Hum Genet 74: 827-845
Achilli A 2005 Am J Hum Genet 76: 883-886
Behar DM 2006 Am J Hum Genet 78: 487-497