October 04, 2009

DRD2 and Uralic admixture in Eastern European plain

From the paper:
The East European (Russian) Plain is a region in which peoples of the Indo-European and Uralic language families have come into contact over an extended period. Uralic-speaking peoples have the longest validated archaeological record in this region [17]. The most recent large-scale migration to this region involved the movement of Slavs (the Indo-European language family) to the east and northeast of their presumed homeland in Central Europe about 500 AD [18,19]. Slavs were not the first Indo-European-speaking people who arrived in the Russian Plain: in the firstmillennium BC, Baltic-speaking tribes occupied a large part of the East European Plain [17]. They were later displaced by Slavic tribes. According to the widely accepted hybridization theory of the origin of Eastern Slavs [20], Slavic populations arriving in the East European Plain were mixed with indigenous Uralic- and, probably, Baltic-speaking people.
Populations in the northwestern (Byelorussians 2 from Mjadel’), northern (Russians from Mezen’ and 6 from Oshevensk; Komi 3), and eastern parts (Russians 4 from Puchezh and Chuvash) of the East European Plain have relatively high frequencies of haplotype B2-D2-A2, which may reflect admixture with Uralic-speaking populations.Uralic genetic substratum in these regions, which were inhabited by Uralic-speaking tribes as late as the Early Middle Ages, was also shown by studies in which other genetic markers were used (mtDNA, Y-chromosome, and autosomal). Thus, the analysis of DRD2 haplotypes supports results on Slavic-Uralic admixture obtained using other markers, mainly neutral and sex-specific markers.
BMC Genet. 2009 Sep 30;10(1):62. [Epub ahead of print]

Haplotype frequencies at the DRD2 locus in populations of the East European Plain.

Flegontova OV, Khrunin AV, Lylova OI, Tarskaia LA, Spitsyn VA, Mikulich AI, Limborska SA.

ABSTRACT: BACKGROUND: It was demonstrated previously that the three-locus RFLP haplotype, TaqI B-TaqI D-TaqI A (B-D-A), at the DRD2 locus constitutes a powerful genetic marker and probably reflects the most ancient dispersal of anatomically modern humans. RESULTS: We investigated TaqI B, BclI, MboI, TaqI D, and TaqI A RFLPs in 17 contemporary populations of the East European Plain and Siberia. Most of these populations belong to the Indo-European or Uralic language families. We identified three common haplotypes, which occurred in more than 90% of chromosomes investigated. The frequencies of the haplotypes differed according to linguistic and geographical affiliation. CONCLUSIONS: Populations in the northwestern (Byelorussians from Mjadel'), northern (Russians from Mezen' and Oshevensk), and eastern (Russians from Puchezh) parts of the East European Plain had relatively high frequencies of haplotype B2-D2-A2, which may reflect admixture with Uralic-speaking populations that inhabited all of these regions in the Early Middle Ages.


Gioiello said...

This paper is interesting also for the discussed origin of Jews: they are divided in 3 groups: Jews 3 are together European 1, Jews 2 are together with European 2 and Jews 3 are together with Ambalakarer, the most distant from Europeans and the closest to Africans (page 39: marker B2D1A2).

Gioiello said...

"B2-D2-A2 is the predominant haplotype in contemporary populations of Middle
Eastern origin (Jews 1 from Ethiopia, Jews 2 from Yemen, and Druze from Israel).
Populations of Levant began to disperse into Europe about 50,000 YBP.
People of that diaspora might have carried B2-D2-A2 as a prevalent haplotype.
However, another haplotype, B2-D1-A2, is the predominant haplotype in
contemporary populations of Europe, for example, in linguistically and
geographically distant populations such as the Irish, Danes, Russians, and Adygeis.
Amplification of this haplotype might have taken place during the initial migration to
Europe or might be associated with confinement in refugia of the last glacial
maximum and reexpansion. According to one of several hypotheses based on
archaeological evidence (reviewed by Zvelebil), Uralic-speaking groups
descended from Europeans who had been confined in the East European refugium in
Ukraine and Southern Russia. It is possible that the people of the East
European refugium retained a high frequency of the B2-D2-A2 haplotype, in contrast
with the other European populations that have spread from other refugia".

This is very interesting: Western Europeans don't come from an Eastern Refugium, but from a Western one.
Jews 3 (Ashkenazim) are genetically Europeans. Jews 2 (from Yemen) have a Middle Eastern ancestry, and Jews 3, who have nothing of Middle Eastern, are Africans (from Ethiopia) like we knew.

Ponto said...

I don't know how to take the results of the study by the Russians. Interesting despite the stereotypical first names of the Russians involved. Lack of imagination and originality in Russia perhaps. A hangover of the Soviet era.

Ashkenazim Jewry have been tested to the point of nausea. Mostly the results show them to be separate from non Jewish Europeans and from the typical inhabitants of the Levantine, Mesopotamian and Arabian parts of the Middle East, but closer to the "Arabs" than the Europeans. Ashkenazim Jewry and Sephardic Jewry in my humble opinion are mostly European converts to Judaism with some minor real, Yehudi, inheritance. Their practice of choosing mates from their religion after the establishment of the religion in Europe is the main reason for the oddity of their SNP results. However even with very low matings outside of the Jewish fold after establishment, the cumulative rate of non Jewish dna ingress would be more than 50%.

I am not sure why the Russians did that study. The need for the creation of an eastern refuge, the pinning of Middle Eastern highs in their DRD2 locus on the Uralic speakers instead of a steady ingress of dna from the Middle East via Anatolia, the Crimea and the rest of the Ukraine into North Russia and Belarus. Not to get offside with Dienekes but it may have come in via the Greeks, and South Slavs along with Orthodox Christianity, Cyril and Methodias, not that those holy men did any breeding. Anything is possible. The Northern Finns and Baltic language speakers are in the European camp so getting admixture from them would not have given them such high B2-D2-A2 rates. I suspect Uralic speakers are easier to accept than Semitic speaking ancient Levantines or Peninsula Arabians. Interesting the Adygei are in the Euro camp despite their high South Asian type SNPs. Yemeni Jews are believed to be converted South Arabians with minor sub Saharan admixture. Their position in the Middle Eastern camp (European2 group in the study) is expected. I don't understand why the Russians did not include other Europeans like Greeks, Spaniards, Germans and Italians for comparison with each other and the peoples of the East European Steppes.

Africans, even the Sanids, as far as this locus is concerned are truly genetically diverse compared to non Africans.

Polak said...

Interesting study. Seems to show exactly what I've noticed with data from 23andme clients.

I'm doing some Structure runs with a whole bunch of Europeans and samples from the HGDP and HapMap, and might soon do a blog entry about that.

Gioiello said...

Ponto, I think you are more expert than me in Genetics, how must I interpret my results? I have been tested by deCODEme and 23andMe. I have:
rs1079597 (112,801,496) A/G
rs1079598 (112,801,484) A/G (probably C/T)
rs1800498 (112,796,798) A/G (probably C/T)
rs1800497 (112,796,038) not tested
rs2234690 (112,796,958) A/T
then heterozygous in all the SNPs.
The paper says that “TaqI B and D (rs1079597 and rs1800498, respectively) are located in the introns of the DRD2 gene and, most probably, have no functional significance” (page 3).

Ponto said...

Well, Gioiello I consider my knowledge that of a layman.

The SNPs located on introns will not have functional significance. It is only the dna located in exons which code for functional proteins used by the cells. Introns get reproduced and then spliced out to produced the functional protein. Saying that, SNPs on introns can indicate how a gene may operate even if the SNPs have nil functional significance.

All those SNPs you mentioned on the DRD2 locus located on Chromosome 11 are important as they indicate how the Dopamine D2 receptor can function. They have been intensely studied for things like Autism, Schizophrenia, Tobacco and Alcohol dependency and how Caffeine affects people's nervous state.

When it comes to your results from Decodeme or 23andme you have to read the probability of a disease outcome for your particular SNP results stated by those companies. You have to take most of those prognostications with a degree of skepticism. For instance, rs1800498 C/T, C is ancestral, T derived, a result of TT compared with CT or CC has a higher rate or chance of developing Schizophrenia, and is involved more often in cases of Autism. However having the TT result does not mean you WILL develop Schizophrenia. Nothing is written in stone.

You did not print your results just the the two single forms of the SNP, and the location on the chromosome which is the 112xxxxxx number. Also for rs1079598 and rs1800498, C/T is the correct form not A/G.

As I said, find out your particular results out of the three possibilities, and check with the companies to see how they assess your "disease" potential for each SNP, then realise that the results are not what will happen to you, but what may happen or never happen.

Gioiello said...

I thank you for your response. The results A/G are those of deCODEme or 23andME, probably due to the strand examined, but I corrected them. Anyway, being heterozygous, probably this does mean that I am a breed from two main types: B2D1A2 (Europe) and B1D2A1(Asian). Then I think no health problem, even though they say I haven’t to abuse of caffeine.