Evidence for mtDNA Admixture between the Finns and the Saami

Abstract

Objectives: The Finns, and to a more extreme extent the Saami, are genetic outliers in Europe. Despite the close geographical contact between these populations, no major contribution of Saami mtDNA haplotypes to the Finnish population has been detected. Methods: To examine the extent of maternal gene flow from the Saami into Finnish populations, we determined the mtDNA variation in 403 persons living in four provinces in central and northern Finland. For all of these samples, we assessed the frequencies of mtDNA haplogroups and examined sequence variation in the hypervariable segment I (HVS-I). The resulting data were compared with published information for Saami populations. Results: The frequencies of the mtDNA haplogroups differed between the populations of the four provinces, suggesting a distinction between northern and central Finland. Analysis of molecular variance suggested that the Saami deviated less from the population of northern Finland than from that of central Finland. Five HVS-I haplotypes, including that harboring the Saami motif and the Asian-specific haplogroup Z, were shared between the Finns and the Saami and allowed comparisons between the populations. Their frequency was highest in the Saami and decreased towards central Finland. Conclusions: The high frequency of certain mtDNA haplotypes considered to be Saami specific in the Finnish population suggests a genetic admixture, which appears to be more pronounced in northern Finland. Furthermore, the presence of haplogroup Z in the Finns and the Saami indicates that traces of Asian mtDNA genotypes have survived in the contemporary populations.

Mitochondrial DNA Variability in Bosnians and Slovenians

“…In addition, in Bosnians CR sequences have been found (at a frequency of 1.4%) belonging to haplogroup H and having HVS II motif 055-057, which is very rare in Europe, being previously observed only in Icelanders (Helgason et al 2000). There is also a considerable difference between subcluster U5b sequences present in Bosnians and Slovenians, since all Bosnian U5b members (4.9%) are defined by the 16189-16270 motif, whereas in Slovenians, two out of three U5b-sequences belong to the specific branch determined by a possible back mutation from T to C at the U5-diagnostic position 16270 (Meinilä et al 2001).…”

“…In Slovenians, the U5a-lineage defined by the substitution 16114A was found at a relatively high frequency of 3.8%. To date, this lineage that has been found with a similarly high frequency only in Finns (Meinilä et al 2001). In addition, Slovenians are characterized by the presence of another lineage frequently occurring in Finns -the U5b-haplotype 16192-16311 (Table 5).…”

“…For phylogenetic analysis, all available published data on the HVS I -RFLP mtDNA variability in West Eurasian populations was used Meinilä et al 2001;Mogentale-Profizi et al 2001;Forster et al 2002). To classify the Slavonic mtDNA haplotypes, a phylogeographic approach, based on the phylogenetic analysis of the spatial distribution of mitochondrial haplotypes and haplogroups determined as a monophyletic clade, was performed (Richards et al 1998).…”

“…The U5b1-lineage with motif 16144-16189-16270 occurs at a frequency of 1.4% in Bosnians, but it is well known that this U5-subcluster has a restricted Northern/Eastern European distribution, being found frequently (8%-52%) in Finns and Saami as well as rarely (0.5%-1.5%) in Slavonic (Russians and Poles) and Baltic (Lithuanians) populations (Sajantila et al 1995;Orekhov et al 1999;Meinilä et al 2001;Kasperaviciute & Kucinskas, 2002;Malyarchuk et al 2002). In addition, Bosnians are characterized by the presence of the Asian-specific haplogroup Z (0.7%), which was previously revealed in Europe in Saami, Finns and Russians (Sajantila et al 1995;Delghandi et al 1998;Orekhov et al 1999;Malyarchuk & Derenko, 2001;Meinilä et al 2001). In Slovenians, the U5a-lineage defined by the substitution 16114A was found at a relatively high frequency of 3.8%.…”

“…Meanwhile, H-16189 sequences are widespread in Europe, but almost all of them do not carry the specific nucleotide combination 153-204 in HVS II. For instance, 6.5% of Finns have HVS I sequence type 16093-16189 or simply 16189, but all of these sequences do not have any specific HVS II motifs Meinilä et al 2001). However, one cannot exclude the possibility that the "Bosnian-specific" H-16189 subcluster is present in the Eastern Mediterranean region, as well as in Southeastern Europe (among Bulgarians and Romanians), since these populations are characterized by 4% of H-16189 sequences according to the HVS I database of .…”