Researchers in ICELAND Find European Genetic Twist

Where did they go... assyria and babylon... Where did they disappear to? Who lays claim to lost tribe heritage. Are the modern day Western Europeans direct descendants of the 10 Northeran tribes...
pokerkid
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Researchers in ICELAND Find European Genetic Twist

Post#1 » Fri Feb 18, 2005 2:17 pm

I found this very interesting, especially since it is in Iceland, because to emigrate there, you have to prove you are of Isrealite stock... Yes I wrote Israelite and not jew because todays modern jew(Khazarian-Ashekenazi-Japethite) for the most part has little or NO Israelite blood in them.
pk

Researchers Find European Genetic Twist

Posted January 17, 2005 1:54PM

DeCode Genetics scientists found that the chromosome 17 inversion is rare
in Africans, almost absent in Asians, but is possessed by 20 percent of
Europeans, the same frequency as in Iceland. The inversion seems to have
been favored by natural selection among Europeans in fairly recent times,
perhaps the past 10,000 years.

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Researchers in Iceland have discovered a region in the human genome that
-- among Europeans -- appears to promote fertility, and maybe longevity
as well.
Although the region, a stretch of DNA on the 17th chromosome, occurs in
people of all countries, it is much more common in Europeans, as if its
effect is set off by something in the European environment.

A further unusual property is that the DNA region has a much more ancient
lineage than most human genes; the researchers suggest, as one possible
explanation, that it could have been inserted into the human genome
through interbreeding with one of the archaic human lineages that
developed in parallel with that of modern humans.

The genetic region was discovered by scientists at DeCode Genetics of
Reykjavik, who have made the Icelandic population -- with its
comprehensive genealogy and medical records -- a prime hunting ground for
the genetic roots of common diseases.

Their finding is published in the Monday issue of Nature Genetics in a
report by Kari Stefansson, Augustine Kong, Hrein Stefansson and other
DeCode scientists.

The report seems likely to receive considerable attention, even though it
raises as many questions as it answers. "I thought it was one of the most
interesting papers in population genetics I have ever read," said Nick
Patterson, a mathematician at the Broad Institute in Cambridge,
Massachusetts, who advised DeCode on the article but has no other
connection with the company.

The region came to light in the search for a schizophrenia-causing gene,
which turned out not to be there. But the DeCode researchers noticed that
the DNA sequences they had examined did not seem to agree with those in
the standard human genome sequence, said Kari Stefansson, DeCode's chief
executive.

The lack of agreement turned out to be caused by the fact that the region
exists in two forms in the Icelandic population. The region is not a
single gene but a vast section of DNA, some 900,000 units in length,
situated in the 17th of the 23 pairs of human chromosomes.

In some Icelanders, the DeCode team found, the section runs in the
standard direction, but in others it is flipped. Looking for any physical
consequence, the DeCode researchers found that women carrying the flipped
or inverted section tend to have slightly more children.

The section carries several known genes, none of which have any obvious
connection with fertility. It is not clear why inverting the section
should have any effect on the number of children, Stefansson said.

But the inversion does increase the rate of recombination, the shuffling
of genes between generations that is a major source of genetic novelty.
That could account for some of the increase in fertility.

The DeCode scientists found that the chromosome 17 inversion is rare in
Africans, almost absent in Asians, but is possessed by 20 percent of
Europeans, the same frequency as in Iceland. The inversion seems to have
been favored by natural selection among Europeans in fairly recent times,
perhaps the past 10,000 years.

"Maybe something switched it on in the European environment, such as an
interaction with diet," said David Reich, a population geneticist at the
Broad Institute.

Stefansson said that another property of the inversion, though one not
described in the new Nature Genetics article, is that it is associated
with longevity. DeCode scientists have located two sites on Icelanders'
genomes where there is some genetic variant that promotes longer life
span.

The chromosome 17 inversion, it turns out, lies at one of these sites. It
occurs at much higher frequency in women over 95 and in men over 90 than
in the normal population. "It seems to confer on people the ability to
live to extreme old age," Stefansson said.

It is particularly surprising that the same genetic element should
promote fertility and longevity since most organisms are obliged to
follow a strategy either of breeding fast during short lives or of living
longer and having fewer children.

"Usually people think of there being a trade-off between fertility and
longevity," said Alan Rogers, a population geneticist at the University
of Utah.

"So we are getting a free lunch here."

Fertility is doubtless affected by different genes in different
populations and DeCode has found one special to Europeans because that is
where it was looking. The increased frequency of the inversion in
Europeans is one of a growing number of examples of recent human
evolution.

The inversion itself, however, is surprisingly ancient. Its age is
revealed by its counterpart, the standard or noninverted section of
chromosome 17.

The standard and inverted regions cannot exchange genetic elements during
recombination because their DNA sequences do not match. Hence, unlike
most of the rest of the genome, which gets shuffled in each generation,
the two forms have enjoyed a separate existence since their creation.

This event presumably happened when the region came adrift from its
parent chromosome and got knitted back in the wrong way round.

When all the known versions of a human gene are compared, in most cases
they turn out to have had a single common ancestor about a million years
ago. But the standard and flipped version of the chromosome 17 region
last shared a common ancestor three million years ago.




© 2005 International Herald Tribune
© 2005 Sci-Tech Today.

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