BAMAD no.56

 DNA and 
 Anthropology Updates 

Updates in DNA studies along with Anthropological Notes of general interest with a particular emphasis on points pertinent to the study of Ancient Israelite Ancestral Connections to Western Peoples as explained in Brit-Am studies.


The Brit-Am Rose
Official Symbol of Brit-Am


BAMAD no. 56
Brit-Am Anthropology and DNA Update
23 July 2009, 2 Av 5769
1. Most Aleut Male Ancestry is European!
2. Nordic Race merely a branch of the Mediterranean Racial Stock?
3. Different Parts of Body give Different DNA!!
SNPs in Non-Cancerous Tissue May Differ From Those In Blood, Study Finds
(b) DNA may differ between tissues
4. Human
mtDNA subject to selection by climate?
5. Distance from Africa explains within-population cranial variation better than climate

Site Contents by Subject Home
Site Map
Contents in Alphabetical Order


This Site

1. Most Aleut Male Ancestry is European!

Ann Hum Biol. 2009 Jul 8:1-16. [Epub ahead of print]

Mitochondrial DNA and Y-chromosome variation in five eastern Aleut
communities: Evidence for genetic substructure in the Aleut population.

Zlojutro M, Rubicz R, Crawford MH.

Since Russian contact in 1741, the Aleut communities of southwestern Alaska have undergone a series of demographic upheavals stemming from forced relocations, disease epidemics, population bottlenecks, and pervasive admixture with European populations. This study investigates the impact of key historical events on the genetic structure of the Aleut population through analysis of mitochondrial and Y-chromosome DNA variation in five eastern Aleut communities. Results from HVS-I sequencing and Y-chromosome typing reveal patterns of variability that exhibit east-west geographic differentiation for the major Aleut haplogroups. This finding is underscored by SAMOVA and Monmonier analyses that identify genetic discontinuities between eastern and western Aleut populations. The majority of Aleut Y-chromosomes were characterized to haplogroups of mostly Russian, Scandinavian and Western European origin (approximately 85%), which is in stark contrast to the 3.6% of Aleut mtDNA lineages identified as non-Native American, and thus indicating a large degree of
asymmetrical gene flow between European men and Aleut women. Overall, this study identifies a significant relationship between geography and genetic variation in the Aleut population, with a distinct substructure along an east-west axis that reflects the combined effects of founder events in aggregate island communities, male-biased gene flow from European populations, and the original peopling of the Aleutian Archipelago.

2. Nordic Race merely a branch of the Mediterranean Racial Stock?
Corded Nordic: The Nordic race is a partially depigmented branch of the greater Mediterranean racial stock. It is probably a composite race made up of two or more basic Mediterranean strains, depigmented separately or in conjunction by a progressive evolutionary process. ...

Hallstatt Nordic: This is the type associated with the Hallstatt Iron Age remains in central Europe, and which probably did not enter Scandinavia much before the middle of the first millennium B.C. [i.e. after ca.500 BCE] It has since been largely replaced in central Europe, but has found a refuge in Sweden and in the eastern valleys of southern Norway. In England this type is largely of Anglo-Saxon and Danish inspiration.

Coon, Carleton S. The Races of Europe. MacMillan, 1939

3. Different Parts of Body give Different DNA!!

(a) SNPs in Non-Cancerous Tissue May Differ From Those In Blood, Study Finds
July 17, 2009
By Andrea Anderson

NEW YORK (GenomeWeb News): A new paper by Montreal researchers is providing evidence that the gene variants found in some non-cancerous tissues may differ from those present in blood samples from the same individual.

"The usual dogma is that your DNA is the same all over the place," senior author Morris Schweitzer, an endocrinologist and lipidologist with McGill University and the affiliated Lady Davis Institute for Medical Research at Montreal's Jewish General Hospital, told GenomeWeb Daily News. But, he said, his team's work suggests that isn't the case.

The researchers, who were studying a condition called abdominal aortic aneurysm, or AAA, found that SNPs in a gene called BAK1 were different in aortic tissue than in blood samples, even in samples taken from the same individuals. The work appears in this month's issue of the journal Human Mutation. Based on the findings, those involved in the study are urging caution in interpreting genetic associations based on DNA from blood samples alone.

"Traditionally when we have looked for genetic risk factors for, say, heart disease, we have assumed that the blood will tell us what's happening in the tissue," lead author Bruce Gottlieb, a researcher affiliated with McGill and the Lady Davis Institute for Medical Research, said in a statement. "It now seems this is simply not the case."

AAA is a rare cardiovascular disease characterized by a ballooning of the abdominal aorta, which provides blood for the abdomen and much of the lower body. Although there are no obvious symptoms, the disease can lead increase the risk of aortic ruptures, a potentially fatal event. AAA affects roughly five to nine percent of the North American population ? particularly men over 60 years old ? and is more common in individuals with cardiovascular risk factors such as smoking, hypertension, or high cholesterol.

Because chronic apoptosis has been implicated in AAA, the researchers decided to investigate a gene called BAK1, which codes for an apoptosis-activating protein, in AAA patients. They used Sanger sequencing to sequence BAK1 cDNA from diseased abdominal aortic tissue and matching blood samples from 31 AAA patients.

When they looked at these sequences, the researchers were surprised to find that the BAK1 sequences in the aortic tissues differed from that in the matched blood samples. The aortic tissue carried a version of the gene containing three SNPs that are rare in the blood. In contrast, the matched blood samples contained a version of BAK1 that did not contain any of the three SNPs found in the aortic tissue samples.

On the other hand, when the team sequenced BAK1 cDNA from healthy aortic tissue obtained from a Quebec transplant service, they found the same three SNPs as in the aortic tissue from the AAA cases. The researchers verified their findings by sequencing both strands of DNA and repeating the sequencing several times.

So far, Schweitzer said it's unclear whether these BAK1 differences in the blood and aortic tissue are the consequence of RNA editing, which changes the messenger RNA but not the gene, or DNA editing, which involves differences in the gene itself.

Down the road, he and his team intend to use pyrosequencing to look at BAK1 sequences from healthy and diseased abdominal aortic tissues in more depth, an approach that could provide insights into whether that tissue contains both majority and minority BAK1 sequences. If that's the case, it would bolster the idea that different genetic sequences can arise through selective pressures in different tissue, Schweitzer added, "You may have different tissue selectivity for different DNA phenotypes."

The team is also interested in investigating whether the pattern they detected holds true in BAK1 sequences from genomic DNA and learning more about whether there are differences in the expression or activity of different BAK1 variants.

Based on the evidence so far, Schweitzer believes the BAK1 differences his team detected resulted from developmental rather than somatic DNA alterations. Such a pattern may not hold true for all genes, he said, but the BAK1 story suggests there could be other genes that vary slightly between blood and other tissues.

That, in turn, highlights the need to assess genetic profiles specifically in tissues of interest, Schweitzer argued, though he noted that that is a lofty goal given the fact that it is difficult or ethically impossible to collect some types of tissue from living individuals.

He and his colleagues also suggested that their findings raise questions about GWAS, many of which rely on DNA profiles obtained from blood samples.

"Genome-wide association studies were introduced with enormous hype several years ago, and people expected tremendous breakthroughs," Gottlieb said in a statement. "Unfortunately, the reality of these studies has been very disappointing, and our discovery certainly could explain at least one of the reasons why."

In an e-mail message to GenomeWeb Daily News, Navigenics Co-founder and Chief Science Officer Dietrich Stephan said the team's work is interesting and deserves further investigation.

"Differences between the germ-line genome and somatic cells is well established in cancer. It is also well described that chimeras can result from early DNA changes in early embryonic development that propagate to form regional differences in the genome across the body," Stephan noted. "It is intriguing to think that such mechanisms could result in common phenotypes, and is a topic that warrants deeper study."

Even so, he does not believe the findings are a blow to the results or rationale behind GWAS in general. Researchers have gained "incredible insight" into disease mechanisms using GWAS over the past few years, Stephan said in his message, adding, "It is much more likely that the missing heritability that we are all searching for will be accounted for by rare DNA variants, copy number variants, and heritable epigenetic modifications than by this mechanism."

(b) DNA may differ between tissues
Recent findings may spell trouble for genome-wide association studies based on DNA obtained through blood samples: Genetic material may vary between blood cells and other tissues in a single individual, a study in the July issue of Human Mutation reports.

The study "raises a very interesting question," Howard Edenberg, director of the Indiana University School of Medicine's center for medical genomics, told The Scientist. Many genome-wide association studies -- especially studies on systemic diseases such as diabetes and atherosclerosis -- depend solely upon DNA harvested from blood samples to identify genes associated with medical conditions. But this study "suggests that looking only at blood, you may miss some things."

Searching for the genes behind a fatal condition called abdominal aortic aneurysm (AAA), researchers from McGill University in Montreal found that complementary DNA from diseased abdominal aortic tissue did not match genomic DNA from leukocytes in blood from the same patient. "We did not expect to find a difference in the tissue [genes] compared to the leukocyte [genes]," said endocrinologist Morris Schweitzer, who led the study.

Schweitzer and his team uncovered three single nucleotide polymorphisms (SNPs) in samples of diseased tissue from 31 AAA patients that were not present in matching blood samples. They also tested five aortic and blood samples from normal individuals and found the same discrepancy. Schweitzer said that the apparent genetic difference between different cells in the body may cast some doubt on genome-wide association studies that only use DNA from blood samples to infer disease states. "I think they may not be accurate because they might not reflect what's in the tissue," he said, adding that researchers should look upon such genetic results "very carefully and very trepidatiously"

4. Human mtDNA subject to selection by climate?


Climate shaped the worldwide distribution of human mitochondrial DNA sequence variation
Fran?is Balloux, Lori-Jayne Lawson Handley, Thibaut Jombart, Hua Liu and Andrea Manica
Proceedings Royal Society B
Abstract: There is an ongoing discussion in the literature on whether human mitochondrial DNA (mtDNA) evolves neutrally. There have been previous claims for natural selection on human mtDNA based on an excess of non-synonymous mutations and higher evolutionary persistence of specific mitochondrial mutations in Arctic populations. However, these findings were not supported by the reanalysis of larger datasets. Using a geographical framework, we perform the first direct test of the relative extent to which climate and past demography have shaped the current spatial distribution of mtDNA sequences worldwide. We show that populations living in colder environments have lower mitochondrial diversity and that the genetic differentiation between pairs of populations correlates with difference in temperature. These associations were unique to mtDNA; we could not find a similar pattern in any other genetic marker. We were able to identify two correlated non-synonymous point mutations in the ND3 and ATP6 genes characterized by a clear association with temperature, which appear to be plausible targets of natural selection producing the association with climate. The same mutations have been previously shown to be associated with variation in mitochondrial pH and calcium dynamics. Our results indicate that natural selection mediated by climate has contributed to shape the current distribution of mtDNA sequences in humans.

5. Distance from Africa explains within-population cranial variation better than climate

This paper is somewhat disappointingly deceptive (as Dienekes points out nicely). They are actually looking at within-population variation in cranial traits and how it varies across the globe. They could have put that in their title.
To be fair, I haven't looked too closely at the paper, and it does look interesting and informative as to the relative roles of demographic vs. selection forces in shaping within-population variation.

Distance from Africa, not climate explains human variation.
Lia Betti, Francis Balloux, William Amos, Tsunehiko Hanihara, Andrea Manica
Proc Roy Soc B Early online
Abstract: The relative importance of ancient demography and climate in determining worldwide patterns of human within-population phenotypic diversity is still open to debate. Several morphometric traits have been argued to be under selection by climatic factors, but it is unclear whether climate affects the global decline in morphological diversity with increasing geographical distance from sub-Saharan Africa. Using a large database of male and female skull measurements, we apply an explicit framework to quantify the relative role of climate and distance from Africa. We show that distance from sub-Saharan Africa is the sole determinant of human within-population phenotypic diversity, while climate plays no role. By selecting the most informative set of traits, it was possible to explain over half of the worldwide variation in phenotypic diversity. These results mirror those previously obtained for genetic markers and show that "bones and molecules" are in perfect agreement for humans.

BAMAD Archives

Join the Brit-Am Ephraimite Discussion Group
Just Send an
with "Subscribe"
in the Subject Line

Main Page

Offerings and Publications

Return to
Question and Answer
Table of Contents