Archiver > GENEALOGY-DNA > 2007-12 > 1198094614

From: "Havelock Vetinari" <>
Subject: [DNA] Apparently, Ukranians are Northern Europeans too
Date: Wed, 19 Dec 2007 15:03:34 -0500


Results promise to improve genetic studies of human disease
September 14, 2006

(SACRAMENTO, Calif.) — An international team of scientists led by
researchers at UC Davis Health System has found that, with respect to
genetics, modern Europeans fall into two groups: a Northern group and
a Southern, or Mediterranean one. The findings, published in the Sept.
14 edition of Public Library of Science Genetics, are important
because they provide a method for scientists to take into account
European ancestry when looking for genes involved in diseases.

"Until now, little has been known about the distribution of genetic
variation in European populations and how much that distribution
matters in terms of doing genetic studies," said Michael Seldin, chair
of the Rowe Program in Genetics at UC Davis Health System. "Now we
will be able to control for these differences in European populations
in our efforts to find genes that cause common diseases."

Seldin, who is also a professor of biochemistry and professor of
medicine at UC Davis, worked with his colleagues to compare genetic
data for 928 individuals. They looked at 5,700 single nucleotide
polymorphisms, called SNPs or "snips." SNPs are changes in which a
single base in the DNA differs from the usual base at that position.
Millions of SNP's have been cataloged in the human genome. Some SNPs
cause diseases, like the one responsible for sickle cell anemia. Other
SNPs are normal variations in the genome. People who share ancestry
will have many SNPs in common.

Seldin and his group set out to discover which SNPs among Europeans
could account for shared common ancestry. "We saw a clustering of
individuals that come from either southern Europe or derived from
populations that left southern Europe, or the Mediterranean, in the
last 2,000 years," Seldin said. This allowed the group to identify a
set of 400 informative SNP markers that scientists could now use to
control for European ancestry when conducting genetic studies of
disease, response to drug treatment, or side effects from therapy.

In addition to future medical applications, the data are also of
interest to anthropologists who study historical human migrations. The
Southern grouping included individuals from Greece, Italy, Portugal
and Spain, as well as Ashkenazi and Sephardic Jews. The Northern group
included people with English, Irish, German, Swedish and Ukranian
ancestry. These groups correspond to those historically divided by the
Pyrenees and Alps mountain ranges.

With respect to population genetics, previous studies have shown that
SNPs correlate broadly with continental ancestry, dividing modern
humans into four large groups: Asia, Africa, Oceana, America and
continental Europe. The new study gives scientists the evidence they
need to further subdivide people with European ancestry into the
Northern and Southern groups when looking for SNPs that may be
involved in disease.

To prove this point, the researchers analyzed two sets of data. They
looked at SNPs associated with rheumatoid arthritis and found that,
when they corrected for ancestry, several of the genes that were
previously believed to be good candidates for being involved in the
disease were no longer candidates at all. They also corrected for
ancestry in a data set looking at lactose intolerance.

"When we did not control for differences in population structure, we
got a lot of false associations," Seldin explained.

Seldin and his colleagues will soon be expanding the current European
study by looking at 500,000 SNPs. They also have plans for similar
studies of other continental populations and for further defining
different subpopulations. Seldin said studies of other continents and
ethnic groups are necessary if science is to get the most out of the
advances made by the Human Genome Project.

"The ultimate aim of these studies is to be able to better define
subgroups and use this information to eliminate false associations,
giving us a better chance of finding true associations for disease
genes," Seldin said.

Other members of the research team include: Russell Shigeta from UC
Davis Health System; Pablo Villoslada at the University of Navarra,
Pamplone, Spain; Carlo Selmi at the San Paolo School of Medicine at
the University of Milan; Jaakko Tuomilehto at the National Public
Health Institute in Helsinki, Finland; Gabriel Silva at the Obras
Sociales del Hermano Pedro in Antigua, Guatemala; John W. Belmont at
Baylor College of Medicine; Lars Klareskog at Karolinska University
Hospital in Stockholm, Sweden; and Peter K. Gregersen at the Feinstein
Institute for Medical Research in Manhassett, New York.

This work was supported by grants from the National Institutes of Health.

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