Country for PR: United Kingdom
Contributor: PR Newswire Europe
Thursday, April 23 2020 - 02:13
Icelandic Genomes Elucidate Neanderthal Heritage of Europeans
REYKJAVIK, Iceland, April 23, 2020, /PRNewswire-AsiaNet/--

- Archaic genetic fragments comprising nearly half the Neanderthal genome are 
circulating in the European gene pool today 

- The average European carries more than 500 such archaic fragments, including 
SNPs linked to prostate cancer risk, iron retention, blood clotting speed, and 

Scientists at deCODE genetics [ ] and colleagues from 
the Max Planck Institute and universities in Denmark and Iceland today publish 
in Nature [ ] the first study 
to use whole-genome sequence data from across a population to shed light on the 
present-day legacy of interbreeding between modern and archaic humans more than 
50,000 years ago. In general terms, the findings support previous estimates 
that most people outside of Africa have approximately 2% archaic ancestry, 
predominantly the result of repeated contact and interbreeding between groups 
of Homo sapiens and multiple Neanderthal individuals. The results also show 
more significant than expected genomic fragments from Denisovans, another 
archaic human species that interbred with both Neanderthal and Homo sapiens. 

Yet the principal significance of this study lies in the unprecedented 
magnitude of data that was used to understand the nature and impact of this 
archaic legacy. In its first phase, the study utilizes whole genome sequence 
(WGS) data from 28,000 Icelanders, nearly ten percent of the entire population, 
and 286 sub-Saharan Africans in the 1000 Genomes project. A limiting factor in 
previous studies has been an overreliance on searching modern genomes for 
sequence fragments derived from just three archaic individuals for whom we have 
good quality sequence data: two Neanderthals and one Denisovan. The authors 
here turn this approach on its head, using the African sequences as a baseline 
for Homo sapiens with no introgression from Neanderthals, and against which 
they compared the Icelandic sequence data. The resulting chromosomal fragments 
found in Icelanders but not shared by Africans comprise a vast catalogue of 15 
million putative archaic fragments.

After combining identical and overlapping fragments, the authors identified 
more than 50,000 distinct archaic fragments covering 38-48% of the readable 
genome. These contain nearly 400,000 single-letter sequence variants, that are 
absent from the African samples. Intriguingly, in the Icelandic samples the 
authors identify nearly 300 "archaic deserts" where there are no archaic 
fragments; these cover nearly 25% of the genome, including the entire X 

To better understand the phenotypic impact of the archaic variants, the deCODE 
team examined them for association with 271 phenotypes in whole-genome data on 
210,000 Icelanders. After winnowing suggestive associations in order to 
eliminate those driven be nearby non-archaic variants, they identified five 
archaic variants with genome-wide significant associations. One has previously 
been linked to decreased levels of prostate specific antigen (PSA) and risk of 
prostate cancer, but was not known to be of archaic origin; two decrease levels 
and mass of hemoglobin; a fourth increases the time it takes for blood to clot; 
and the fifth decreases height. 

"Whether individually or collectively, our genome enables us to learn more 
about who we are by telling us where we come from. This paper is a kind of 
ancestry report for one branch of our species, and it's telling us that in this 
particular neighborhood we are not just Homo sapiens but also the descendants 
of ancient archaic humans – cousin species whose lineage is thus not entirely 
extinct," said Kari Stefansson, CEO of deCODE and a senior author on the paper. 
"We are scratching the surface of what this hybrid legacy means. What we know 
is that in the 50,000 years from their time to this, our adaptability and 
diversity have enabled us to mix and move, settle and thrive in every corner of 
the planet as they did not. In these dark days we would do well to remember 
that our differences are literally the mark of our success, and so to help each 
other as best we can."

Based in Reykjavik, Iceland, deCODE is a global leader in analyzing and 
understanding the human genome. Using its unique expertise in human genetics 
combined with growing expertise in transcriptomics and population proteomics 
and vast amount of phenotypic data, deCODE has discovered risk factors for 
dozens of common diseases and provided key insights into their pathogenesis. 
The purpose of understanding the genetics of disease is to use that information 
to create new means of diagnosing, treating and preventing disease. deCODE is a 
wholly-owned subsidiary of Amgen (NASDAQ:AMGN). 

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Thora Kristin Asgeirsdottir

SOURCE: deCODE genetics