Swedish Genetics: Abstracts and Summaries

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Swedish people live in the central Scandinavian country of Sweden, which shares land borders with Norway and Finland and is also near Denmark. The Swedish language is in the North Germanic family and is closely related to Norwegian and Danish.

In "The Swedish DNA Project", Y-DNA haplogroups include, in descending order of frequency, I1, R1b, R1a, N, I2, Q, E1b, J2, and G. This is consistent with other studies that show about 35-40% of Swedish males carry I1 or its subclades. I1 originated in northern Europe, probably in Denmark. In the project are participants with I1 (L22-) itself as well as I1b, I1d, I1d1, and I1d4. R1b, so common in western Europe and which was found in the ancient Bell Beaker culture, is found among these Swedes in subclades like R1b1a2a1a1a and R1b1a2a1a1a4.

H is by far the most common mtDNA haplogroup in the project, followed by U, K, J, T, and much smaller percentages of others. Subclades of H found among these Swedes include H1a2, H2a2, H6a1b, H11a, and others.

Among 23andMe's customers, 10-12% of Swedes carry the T red hair allele in the R160W gene (one of the highest frequencies in the world), 6-8% carry the T red hair allele in the R151C gene, and 0-2% carry the C red hair allele in the D294H gene.

A. O. Tillmar, M. D. Coble, T. Wallerström, and G. Holmlund. "Homogeneity in mitochondrial DNA control region sequences in Swedish subpopulations." International Journal of Legal Medicine 124:2 (March 2010): pages 91-98. First published electronically on July 10, 2009.
      DNA samples were collected from 296 Swedish males from 7 different regions of Sweden and examined in the laboratory for their mitochondrial DNA (mtDNA). Excerpts from the Abstract:

"[...] the Swedish population was shown to have high haplotype diversity with a random match probability of 0.5%. Almost 47% of the tested samples belonged to haplogroup H and further haplogroup comparison with worldwide populations clustered the Swedish mtDNA data together with other European populations. AMOVA analysis of the seven Swedish subregions displayed no significant maternal substructure in Sweden [...] Our conclusion from this study is that the typed Swedish individuals serve as good representatives for a Swedish forensic mtDNA database. Some caution should, however, be taken for individuals from the northernmost part of Sweden (provinces of Norrbotten and Lapland) due to specific demographic conditions. Furthermore, our analysis of a small sample set of a Swedish Saami population confirmed earlier findings that the Swedish Saami population is an outlier among European populations."

Elina Salmela, Tuuli Lappalainen, Jianjun Liu, Pertti Sistonen, Peter M. Andersen, Stefan Schreiber, Marja-Liisa Savontaus, Kamila Czene, Päivi Lahermo, Per Hall, and Juha Kere. "Swedish Population Substructure Revealed by Genome-Wide Single Nucleotide Polymorphism Data." PLoS ONE 6(2) (February 9, 2011): e16747.
      350,000 single nucleotide polymorphisms (SNPs) were genotyped from 1525 Swedes. The researchers compared the Swedish samples to 3,212 samples from populations worldwide, "including Finns, northern Germans, British and Russians".

Excerpts from the Abstract:

[...] The Swedes - especially southern Swedes - were genetically close to the Germans and British, while their genetic distance to Finns was substantially longer. The overall structure within Sweden appeared clinal, and the substructure in the southern and middle parts was subtle. In contrast, the northern part of Sweden, Norrland, exhibited pronounced genetic differences both within the area and relative to the rest of the country. These distinctive genetic features of Norrland probably result mainly from isolation by distance and genetic drift caused by low population density. [...] Overall, our results underline the potential of genome-wide data in analyzing substructure in populations that might otherwise appear relatively homogeneous, such as the Swedes."

An excerpt from the body of the paper:

"Genetically the Swedes have appeared relatively similar to their neighboring populations - for example the Norwegians, Danish, Germans, Dutch and British - both in a classical study based on a small number of autosomal markers [11] and in the recent genome-wide studies [1]-[6], [12]. Similar patterns of a close relationship with neighboring populations have been observed in the Y-chromosomal and mitochondrial DNA (mtDNA) variation [13]. In contrast, the Finns [...] do not appear genetically very close to the Swedes although they are geographically nearby."

Keith Humphreys, Alexander Grankvist, Monica Leu, Per Hall, Jianjun Liu, Samuli Ripatti, Karola Rehnström, Leif Groop, Lars Klareskog, Bo Ding, Henrik Grönberg, Jianfeng Xu, Nancy L. Pedersen, Paul Lichtenstein, Morten Mattingsdal, Ole A. Andreassen, Colm O'Dushlaine, Shaun M. Purcell, Pamela Sklar, Patrick F. Sullivan, Christina M. Hultman, Juni Palmgren, and Patrik K. E. Magnusson. "The Genetic Structure of the Swedish Population." PLoS ONE 6(8) (August 4, 2011): e22547.
      This is a detailed survey of 5174 Swedes from many parts of Sweden. Genome-wide single nucleotide polymorphisms (SNPs) from them were studied. The researchers concluded that the Swedes aren't a homogeneous people. Those in the south of Sweden are closely related to people in northern Germany who descend to a large extent from Neolithic-era farmers who arrived in Europe from the Middle East after some tribes already had settled in Europe, while those in central Sweden have a higher quantity of indigenous Scandinavian ancestry stemming from hunter-gatherers, and many of those in northern Sweden are closely related to Finnish or Saami people. Excerpts from the Abstract:

"[...] We observed strong differences between the far northern counties and the remaining counties. The population of Dalarna county, in north middle Sweden, which borders southern Norway, also appears to differ markedly from other counties, possibly due to this county having more individuals with remote Finnish or Norwegian ancestry than other counties. An analysis of genetic differentiation (based on pairwise Fst) indicated that the population of Sweden's southernmost counties are genetically closer to the HapMap CEU samples of Northern European ancestry than to the populations of Sweden's northernmost counties. In a comparison of extended homozygous segments, we detected a clear divide between southern and northern Sweden with small differences between the southern counties and considerably more segments in northern Sweden. Both the increased degree of homozygosity in the north and the large genetic differences between the south and the north may have arisen due to a small population in the north and the vast geographical distances between towns and villages in the north, in contrast to the more densely settled southern parts of Sweden. [...] We have shown that genetic differences within a single country may be substantial, [...]"

Tuuli Lappalainen, V. Laitinen, Elina Salmela, P. Andersen, K. Huoponen, M.-L. Savontaus, and Päivi Lahermo. "Migration Waves to the Baltic Sea Region." Annals of Human Genetics 72:3 (May 2008): pages 337-348. First published online on February 21, 2008.
      The Swedish samples in this study were derived only from ethnic Swedes. 307 Swedish mtDNA samples and 160 Swedish Y-DNA samples were obtained and compared with those of other ethnic groups: people from Finland, Karelia, Russia, Estonia, Setoland, Latvia, Lithuania. The total number of samples exceeded 1,200.

The Swedes' Y-chromosomal haplogroup frequencies are listed in Table 1 as follows:
DE: 1.3%
F* (xI,J,K): 4.4%
I1a: 35.6%
I1c: 1.9%
K* (xN,P): 0.6%
N3: 14.4%
P* (xQ,R): 4.4%
R1a1: 24.4%
R1b: 13.1%

The Swedes' mtDNA haplogroup frequencies are listed in Table 3 as follows:
C: 0.3%
H: 8.1%
H1: 12.7%
H1a: 2.3%
H1b: 1.3%
H1f: 1%
H2a1: 9.1%
H2: 2%
H3: 3.9%
H5: 1.3%
H6: 3.9%
I: 3.3%
J: 2.3%
J1: 2.6%
J1a: 0.3%
J1b1: 0.3%
J2: 0.3%
K: 7.5%
T: 7.2%
T1: 2.9%
U: 3.3%
U2: 0.3%
U3: 1.3%
U4: 2.9%
U5: 0.7%
U5a: 4.6%
U5a1: 2%
U5b: 3.9%
U5b1b: 2%
V: 1.3%
W: 1.3%
X: 0.3%
Z: 0.3%
Other haplogroup(s): 3.3%

Excerpt from the paper:

"[...] The Swedish samples are mainly from eastern Sweden. [...] [Y-DNA] Haplogroup I1a had a high frequency of up to 40% in Sweden and Western Finland and intermediate frequencies in the other Finno-Ugric populations, while it was almost absent among Latvians and Lithuanians (Table 1). In the network the Finnish and Swedish haplotypes appear to be separate (Fig. 3b), which is supported by the SAMOVA analysis that separated the Swedes/Balts from the others with a moderate 6.9% of variation among these groups. The highest diversities were in Eastern Finland, the Baltic states, and Sweden (Table 2). The age of the haplogroup was 7,700 years (Table 2). [...]"

Tuuli Lappalainen, Ulf Hannelius, Elina Salmela, Ulrika von Döbeln, Cecilia M. Lindgren, K. Huoponen, M.-L. Savontaus, J. Kere, and Päivi Lahermo. "Population Structure in Contemporary Sweden—A Y-Chromosomal and Mitochondrial DNA Analysis." Annals of Human Genetics 73:1 (January 2009): pages 61-73. First published online on October 22, 2008.
      820 females and 883 males born in Sweden were genetically tested and compared with people from nearby countries. Not all of these Swedish samples were purely ethnic Swedish, however, and this was intentional on the part of the researchers so they could capture a snapshot of the people of contemporary Sweden. The Y-DNA haplogroup I1a, so common among Swedes, was less common in cities that had recent immigrants, as one would expect, and these immigrants brought haplogroups common in Africa, the Middle East, the Balkans, Eastern Europe, and East Asia.

Excerpts from the Abstract:

"[...] 14 Y-chromosomal and 34 mitochondrial DNA SNPs were genotyped. The haplogroup frequencies of the counties closest to Finland, Norway, Denmark and the Saami region in the north exhibited similarities to the neighbouring populations, resulting from the formation of the Swedish nation during the past millennium. Moreover, the recent immigration waves of the 20th century are visible in haplogroup frequencies, and have led to increased diversity and divergence of the major cities. Signs of genetic drift can be detected in several counties in northern as well as in southern Sweden. With the exception of the most drifted subpopulations, the population structure in Sweden appears mostly clinal. [...]"

Excerpts from the body of the text:

"[...] The mtDNA haplogroup with the strongest geographical cline, U5b, is known to have high frequencies among the northern Saami population, consistent with our results (Tambets et al. 2004). The high frequency of the Y-chromosomal R1b in the south, observed also by Karlsson et al. 2006; is consistent with its abundance in Central Europe and Denmark (Semino et al. 2000; Brion et al. 2005). [Y-chromosomal] Haplogroup R1a1 is more common in Norway than in Sweden (Dupuy et al. 2006), and its high frequency in Värmland/Dalarna and Halland supports the historically plausible connection to Norway (Lindqvist, 2006). Y-chromosomal haplogroup N3 (Lappalainen et al. 2006) and mtDNA haplogroup H1f (Loogväli et al. 2004; Lappalainen et al. 2008) are common in Finland, and had increased frequencies in several Swedish counties with historical ties to Finland: Eastern Svealand was the most important destination of the Finnish immigration wave in the 1970's; in Norrland the Finnish influences date back to ancient times and in Dalarna to the 17th century (Pitkänen 1994). [...]"

Ulf Hannelius, Elina Salmela, Tuuli Lappalainen, Gilles Guillot, Cecilia M. Lindgren, Ulrika von Döbeln, Päivi Lahermo, and Juha Kere. "Population substructure in Finland and Sweden revealed by the use of spatial coordinates and a small number of unlinked autosomal SNPs." BMC Genetics 9:54 (2008). Published online on August 19, 2008.
      Autosomal single nucleotide polymorphisms (SNPs) were genotyped from 2,044 people from Sweden and 657 people from Finland, and short tandem repeats (STRs) were genotyped from 465 people from Finland. The Swedish samples in this study weren't limited to ethnic Swedes. All of the Finnish samples came from middle-aged men who had all 4 of their grandparents born in the same geographical area.

Excerpt from the Results section:

"[...] We saw significant population structure within Finland but not between the countries or within Sweden, and isolation by distance within Finland and between the countries. [...]"

Excerpt from the section titled "Genetic differences between Swedes and Finns":

"The principal component analysis clearly separated the Finnish regions and Eastern and Western counties from the Swedish as well as the Finnish regions and counties from each other (Figure 2C and 2D). Geneland showed three clusters (Figure 3B), roughly corresponding to Sweden, Eastern Finland and Western Finland. Thus, Geneland was able to correctly identify the country of origin of the individuals despite the lower quality of the Swedish data."

Jukka U. Palo, Markus Pirttimaa, Auli Bengs, Vivian Johnsson, Ismo Ulmanen, Matti Lukka, Bjarne Udd, and Antti Sajantila. "The effect of number of loci on geographical structuring and forensic applicability of Y-STR data in Finland." International Journal of Legal Medicine 122:6 (2008): pages 449-456.
      Although this Y-DNA study concentrates on Finns (from the western, central, and eastern regions of Finland), Swedish-speaking people who live in the municipality of Larsmo in western Finland were also tested. The Y-STR variation significantly differed between the Swedes and the Finns. The study found that the Swedes "differed significantly from all the other populations". The most common Y-DNA haplogroup of the Swedes of Finland is within I, which of course is also very prevalent among Swedes in Sweden. The haplogroup I1a is found among some ethnic Finns in western Finland, who are more closely genetically related to Swedes than eastern Finns are.

Mari Nelis, Tõnu Esko, Reedik Mägi, Fritz Zimprich, Alexander Zimprich, Draga Toncheva, Sena Karachanak, Tereza Piskáčková, Ivan Balaščák, Leena Peltonen, Eveliina Jakkula, Karola Rehnström, Mark Lathrop, Simon Heath, Pilar Galan, Stefan Schreiber, Thomas Meitinger, Arne Pfeufer, H-Erich Wichmann, Béla Melegh, Noémi Polgár, Daniela Toniolo, Paolo Gasparini, Pio D'Adamo, Janis Klovins, Liene Nikitina-Zake, Vaidutis Kučinskas, Jūratė Kasnauskienė, Jan Lubinski, Tadeusz Debniak, Svetlana Limborska, Andrey Khrunin, Xavier Estivill, Raquel Rabionet, Sara Marsal, Antonio Julià, Stylianos E. Antonarakis, Samuel Deutsch, Christelle Borel, Homa Attar, Maryline Gagnebin, Milan Macek, Michael Krawczak, Maido Remm, and Andres Metspalu. "Genetic Structure of Europeans: A View from the North-East." PLoS ONE 4(5) (May 8, 2009): e5472.
      3,112 European people (including among others Swedes, Estonians, Finns, Russians, Poles) were genetically tested. The Swedish samples came from the capital city of Sweden, Stockholm. The study describes a genetic barrier "between the Baltic region and Poland on the one hand, and Sweden on the other". Further down it refers to the "barrier [that] emerged between the Eastern Baltic region and Sweden, but not between the Eastern Baltic region and Poland". The study's data comparing Swedes with Finns is consistent with how Swedes are descended mainly from Germanic people but came to mix somewhat with Finns (especially in the case of northern Swedes, some of whom were tested here).

Valentina Moskvina, Michael Smith, Dobril Ivanov, Douglas Blackwood, David StClair, Christina Hultman, Draga Toncheva, Michael Gill, Aiden Corvin, Colm O'Dushlaine, Derek W. Morris, Naomi R. Wray, Patrick Sullivan, Carlos Pato, Michele T. Pato, Pamela Sklar, Shaun Purcell, Peter Holmans, Michael C. O'Donovan, Michael J. Owen, George Kirov, and the International Schizophrenia Consortium. "Genetic Differences between Five European Populations." Human Heredity 70:2 (2010). Also published online on July 8, 2010.
      SNP allele frequencies were compared between populations of Sweden, Scotland, Ireland, Portugal, and Bulgaria.

Monica Leu, Keith Humphreys, Ida Surakka, Emil Rehnberg, Juha Muilu, Päivi Rosenström, Peter Almgren, Juha Jääskeläinen, Richard P. Lifton, Kirsten Ohm Kyvik, Jaakko Kaprio, Nancy L. Pedersen, Aarno Palotie, Per Hall, Henrik Grönberg, Leif Groop, Leena Peltonen, Juni Palmgren, and Samuli Ripatti. "NordicDB: a Nordic pool and portal for genome-wide control data." European Journal of Human Genetics 18 (2010): pages 1322-1326. Published online on July 28, 2010.
      Table 1 tells us that both male and female Swedes were sampled for this study. 2,087 samples came from studies exclusively concentrating on Sweden, while 1,467 additional samples were divided between Sweden and Finland of which 371 came from Sweden, for a grand total of 2,458 Swedish samples. Figure 1a displays genetic variation between the Swedish ("SWE"), Danish, and Finnish populations. Another version of the same genetic variation map is here. Some overlap was found between Swedish and Danish samples, and some western Finns also overlapped with Swedes.

Kimberly Sturk-Andreaggi, Martin Bodner, Joseph D. Ring, Adam Ameur, Ulf Gyllensten, Walther Parson, Charla Marshall, and Marie Allen. "Complete Mitochondrial DNA Genome Variation in the Swedish Population." Genes (Basel) 14:11 (October 25, 2023): article number 1989.
      All samples here come from Sweden-born individuals from the TwinGene project, as was stated by the article "SweGen: a whole-genome data resource of genetic variability in a cross-section of the Swedish population". Thus, many of these samples represent the mtDNA lines of ethnic Swedes. There's also evidence that certain other samples come from Saami and Finns living in Sweden. They identified "821 mitogenome haplotypes" out of 934 total samples. As shown in Supplementary Table S1, they include such mtDNA haplogroups as H2a1n, H6a1b2, U8a1a1a, J1c7a (including 2 examples of what YFull MTree calls J1c7a5a by virtue of carrying the mutations A188G and A13470G), HV1a'b'c (in what YFull MTree calls HV1a'b'c2 because it includes the mutation C10897T), H1b, H1as, H1bw, H7, H15b, H56, J1b1a1, J1c3e2, J1c4, T1a1, T1a1b, T1a1j, T1a1k, T2b, U2e1a1, U5b1b1a, N1a1a1a2, and Z1a1a. As expected, most of the haplogroups were already known to be in Scandinavia and Europe more generally. However, the East Eurasian haplogroups D4i and G3a3 were detected in one sample each, "likely the result of increased immigration from more distant countries during the end of last century".