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torsdag 3. november 2011

Finding South-Saami ancestry in Scandinavians

It appears that the local analysis been done so far had weaknesses. It appears not managed to catch all people of at least partly South-Saami ancestry. I suspect the reason have been in the MDS program itself with different sample sizes in clusters and numbers of clusters affecting the result especially for partly mixed individuals. When including more outside populations it appears to make genetic distinctions clearer within Fennoscandia possibly from the earlier mentioned reasons.

Ref pop: French, Italians, Hungarians, Romanians, Vologda Russians, Norwegians, Swedes, Finns and Saami.
Number of SNP: 530k (not pruned) - 22 autosomal chromosomes.
PLINK MDS plot dimensions: 3

In the earlier local analysis it appeared obviously that samples NO6, NO7 and SWE7 must have been at least of partly Saami background with especially SWE7 plotting "weird", but not as obvious for sample SWE11 who earlier in the local analysis showed some weak pull out of the Scandinavian cluster. In this newest MDS run however SWE11 seperated very clearly from the Scandinavian cluster together with unrelated NO6 and SWE7.

Lets look first at the new MDS plot. In this plot top-bottom axis appears to be east and west geneticially speaking with the Vologda Russians and Belorussians at the top edge representing the most eastern population and Saamis at first glance the most "western" population with following Finns, Scandinavians and French.

Lets look at the second dimension in the left-right axis. This appears to reflect Siberian influence in Europe. The Saamis and many Finns appears to have the strongest influence from Siberia with Vologda Russians, Belorussians and Scandinavians following. The lowest Siberian influence appears to be among the Italians, French and Romanians.

So what differentiate North-Saami from South-Saami? It can be shown in the plot below. In Dimension 2 (D2) where the North-Saami and South Saami cleary is alone at the lower part of the plot in the extreme "West". Obviously both Saami group share ancestry in this common European dimension. This picture however change when we compare to Dimension 1 (D1) that shows levels of Siberian ancestry. Here the North-Saami peaks together with eastern Finns to the far right, while the South-Saami have levels comparable to Swedish Finns.

About the South Saami samples: SWE7 is confirmed at least partly of Saami background but not of North Saami background. SWE11 have also some geneological confirmed minor Saami background and have most of the origin from current and earlier known non-North-Saami areas. No information is known about NO7.

As comparisment NO6 who have geogaphical origin in the North-Saami area seperate very clearly from NO7, SWE7 and SWE11 by pulling straight at the North-Saami cluster (SA1-SA4) and appearing immediate between the Scandinavain and North-Saami cluster demonstrating that the Saami origin is different for NO7, SWE7 and SWE11.

So apparantly SWE7, SWE11 and NO7 have South-Saami background.

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