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Accuracy of Large-Scale Genome Scanning Services

Although the genome scanning services offered by companies such as 23andMe, deCODEme, and SeqWright have been front and center in the press the last few weeks, I’m sure that the following information will not be included in any of the reports.

Comparisons

Two different sources have concluded that the scanning service offered by 23andMe and deCODEme, who use different types of Illumina SNP Chips, are highly reproducible. In January 2008, Ann Turner compared the results of testing at deCODEme and 23andMe, and concluded that of the 560,163 SNPs that overlapped and had a “call” (meaning there was a measurable result), they agreed on 560,128 and disagreed on 35. Ann wrote in January:

In all of [the disagreed calls], one company would make a homozygous call while the other company made a heterozygous call – there were no cases where they made a completely discordant call. All in all, I’d say that is pretty impressive.

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The New Y-Chromosome Tree to be Released Tomorrow

A long-anticipated new version of the Y-Chromosome Tree will be released in the journal Genome Research tomorrow (Wednesday, April 2nd). In the paper, scientists from the University of Arizona and Stanford University use recent SNP data and research to reformulate the familiar Y-chromosome tree (see, for example, the current tree at ISOGG). Here is the full text of the press release.  The paper should appear here as soon as it is made available by Genome Research tomorrow.

From the press release:

In an article published online today in Genome Research (www.genome.org), scientists have utilized recently described genetic variations on the part of the Y chromosome that does not undergo recombination to significantly update and refine the Y chromosome haplogroup tree. The print version of this work will appear in the May issue of GenomeResearch, accompanied by a special poster of the new tree.

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Interesting DNA Links – March 26, 2008

Here are a few of the many interesting links from the DNA blogosphere:

  • DNA Testing Firms Eye Consumers (BBC) – yet another article that looks at both sides of the “should you test” debate.
  • Genetic Testing Gets Personal (Washington Post) – a lengthy discussion of many different types of DNA testing.
  • The Scientific Studies/Papers Page at ISOGG – I’ve been meaning to share this one for a while. The page describes methods for obtaining and reading scientific papers about genetic genealogy (or any other scientific topic, for that matter). This is a helpful resource for anyone who is interested in learning more about the science behind genetic genealogy.

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The Six Founding Native American Mothers

BeringiaIf you’re interested in DNA, Native American History, or genetic genealogy, then you’re undoubtedly heard of a new paper from PLoS ONE called “The Phylogeny of the Four Pan-American mtDNA Haplogroups: Implications for Evolutionary and Disease Studies.” The authors, from all around the world (including Ugo A. Perego from SMGF and Antonio Torroni from Italy) analyze over 100 complete Native America mtDNA genomes. From the abstract:

“In this study, a comprehensive overview of all available complete mitochondrial DNA (mtDNA) genomes of the four pan-American haplogroups A2, B2, C1, and D1 is provided by revising the information scattered throughout GenBank and the literature, and adding 14 novel mtDNA sequences. The phylogenies of haplogroups A2, B2, C1, and D1 reveal a large number of sub-haplogroups but suggest that the ancestral Beringian population(s) contributed only six (successful) founder haplotypes to these haplogroups.”

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More Interesting Links From The Genetic Genealogist

TGG3 On the heels of my recent post discussing all the interesting information that’s recently entered the blogosphere about genetic genealogy and DNA studies, here are a few more:

Misha Angrist, one of the Personal Genome Project’s “First 10“, wrote an article about the inevitability of DNA sequencing at News Observer. The article is a response to a recent editorial in the NEJM.

VisiGen Biotechnologies announces that IF their technology works as planned, the $1000 genome is just months or a few years away. See more at Genetics and Health and Next Generation Sequencing. Pacific Biosciences (PacBio) has made a similar announcement.

John Hawk’s Anthropology Weblog, “Viking Ancestry, Surnames and Medieval Genetics” examines a recent study in Molecular Biology and Evolution “investigating whether the Viking influence on surnames in England is mirrored by Y chromosomes.” It’s a great post, especially for genetic genealogists.

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Interesting Links From The Genetic Genealogist

dna-stock_phixr.JPGThere is so much to talk about, and so little time to write. So I thought I’d do a round-up post to bring these interesting stories to your attention. I hope you enjoy the following:

Of great significance to genetic genealogists, the Wall Street Journal says that as many as 1 in 25 children are the result of non-paternal events! The number seems very high, but it is based on a 2005 report in the Journal of Epidemiology and Community Health studying families in “the U.S., Europe, Russia, Canada, South Africa and several other countries.”

SNP studies are coming out left and right. The recent studies have examined variation among genomes from numerous populations using SNP chips that examine 600,000 or more SNPs. See more at GenomeWeb News, The Spittoon, and Genetic Future. A great quote comes from a discussion of one of these SNP studies at the terrific Dienekes’ Anthropology Blog:

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Famous DNA Review, Part IV – Jesse James

image Jesse Woodson James, born September 5, 1847 and died April 3, 1882, was an infamous American outlaw. Despite strong evidence that James was killed on April 3, 1882, some theorized that his death was staged and that he in fact survived to father additional children.

In 1995, researchers set out to use relatively new DNA analysis to examine the rumors surrounding James’ death. They exhumed the body believed to be that of James from the Mt. Olivet Cemetery in Kearney, Nebraska. Although the remains were poorly preserved, the scientists were able to obtain DNA from two of four teeth. They also had DNA from two hairs that were recovered in 1978 from James’ original burial site on the James farm.

The mtDNA HVR1 sequence from the teeth and hairs were identical and belonged to Haplogroup T2, with 5 mutations relative to the CRS (16126C, 16274A, 16294T, 16296T, and 16304C).

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Did Megan Smolenyak Smolenyak Marry Her Cousin?

What are the chances that Megan Smolenyak would meet and marry a man with the surname Smolenyak without being at least distantly related to him? What if the two surname lines came from the same area of the world? I’m sure that everyone who has heard of Megan has wondered how she came by the double last name.

Megan writes “Did I Marry My Cousin” at Megan’s Roots World to introduce a new segment at Roots Television about how she used genetic genealogy to analyze the question. The segment is available here. I highly recommend stopping by to learn more about this particular use of genetic genealogy, especially since I’m not going to give you the answer!

What is the Mutation Frequency Rate of mtDNA?

rw.gifAs I was reading through the GENEALOGY-DNA list from Rootsweb this morning, I came across a great question about the frequency of mutation of mitochondrial DNA (mtDNA).

The listmember asks “I am wondering if anyone would know the odds of having a mutation between my brother and me in our mtDNA. Marker 16163 is G for one of us and A for the other…” This is a great question, and one that I’ve been asked as well.

In response, Ann Turner writes “The mutation rate hasn’t been studied in the detail I’d like to see. The largest study for the hypervariable regions was based on deep-rooting pedigrees from Iceland. They found 3 mutations out of 705 transmission events.”

The study, available here (pdf, HT: Ann Turner) was conducted through deCODE Genetics and Oxford University. They used 26 Icelandic ancestral trees to identify maternally-related individuals, and sequenced 272 mtDNA control regions representing a total of 705 transmission events. The researchers found a total of three mutations, resulting in a mutation rate of 0.0043 per generation, or 0.32/site/1 million years. A previous study (Parsons et al., 15 Nature Genetics 363 1997) found a total of 10 mutations in 327 transmission events for a frequency of 2.5/site/1 million years, and yet another study found 2 mutations in 81 transmissions for a rate of 0.75/site/1 million years (Howell et al., 59 Am J Hum Genet 501). The huge differences in these numbers suggests that much more research needs to be done, probably with a much larger dataset. If I had unlimited funds, I would also be interested to see if there are different mutation rates among haplogroups, as well as a number of other factors.

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Personal Genomics in The New England Journal of Medicine

genome-in-a-bottle.jpgA report published in the New England Journal of Medicine entitled “Letting the Genome Out of the Bottle – Will We Get Our Wish?” is getting a lot of coverage elsewhere, but I thought I’d add my two cents. The report’s authors are largely concerned with quality control, clinical validity (the actual predictive value of genetic tests), and utility (the balance of family history and genetic testing) of genome scans offered by companies such as 23andMe, deCODEme, and Navigenics. They also suggest that people wait for the science to catch up before purchasing genome scans. There is an NEJM audio interview with Muin Khoury, one of the authors of the study about the subject. Note that this particular report is about medical implications of genetic testing, not about genetic genealogy (two very different topics that were very confusingly jumbled in the recent article “A High-Tech Family Tree” from U.S. News & World Report).

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