Small Matching Segments – Friend or Foe?

There has been a great deal of conversation in the genetic genealogy community over the past couple of weeks about the use of “small” segments of matching DNA. Typically, the term “small” refers to segments of 5 cM and smaller, although some people include segments of 7 cM or even 10 cM and smaller in the definition.

The question, essentially, is whether small segments of DNA can be used as genealogical evidence, and if so, how they can be used.

While it may seem at first that all shared segments of DNA could constitute genealogical evidence, unfortunately some small segments are IBS, creating “false positive” matches for reasons other than recent ancestry. These segments sometimes match because of lack of phasing, phasing errors, or a variety of other reasons. One thing, however, is clear: there is no debate in the genetic genealogy community that many small segments are false positive matches. There IS debate, however, regarding the rate of false positive matches, and what that means for the use of small segments as genealogical evidence.

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Ancient Genomes at GEDmatch

A great resource from Jay Chandrakumar at Genetic Genealogy Tools (www.y-str.org) – SNPs extracted from sequenced ancient genomes and loaded into GEDmatch. Try out admixture tools with these GEDmatch profiles, but don’t expect many matches in One-to-Many!

Denisova – GEDMatch# F999903

Mezmaiskaya Neanderthal #1 – GEDMatch# F999909

Altai Neanderthal #2 – GEDMatch# F999902

Palaeo-Eskimo 2000 BC – GEDMatch# F999906

Clovis-Anzick – GEDMatch# F999912

For example, here’s the Palaeo-Eskimo 2000 BC (F999906) profile in MDLP K23b:

F999906 GEDmatch


















Identifying Ötzi the Iceman’s Relatives

In 1991, German tourists in the Alps discovered the mummified remains of a man who died approximately 5,000 years ago. Named Ötzi, the remains have been studied extensively and have revealed a wealth of information about life in this region.

Ötzi’s DNA

Of note to genetic genealogists, Ötzi’s DNA has also been the subject of extensive analysis.  In February 2012, sequencing of Ötzi’s full genome was announced (see here and here) which revealed, among other things, that the Iceman probably had brown eyes, belonged to blood group O, and was lactose intolerant.  He may also have had Lyme disease, as the genome of the infectious agent  Borrelia burgdorferi was also identified in the sequencing effort.

Ötzi’s Y-DNA belongs to a subclade of Haplogroup G defined by the SNPs M201, P287, P15, L223 and L91 (G-L91).  As far as I know, he has not yet been typed for any of the subclades downstreaming from G-L91. More information can be found at the G-L91 page of the Haplogroup G Project, and elsewhere online.

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Napoleon Bonaparte’s Y-DNA Haplogroup Belonged to E1b1b1c1* (E-M34)

Researchers have recently discovered that Napoleon Bonaparte’s Y-DNA belongs to haplogroup E1b1b1c1* (M34+).

Dominique Vivant Denon was the director-general of French museums under Napoleon.  Denon made a reliquary (a container for relics) that included the beard of Henry IV, a tooth from Voltair, and a lock of Bonaparte’s hair. [1. B. Foulon, ed., Dominique-Vivant Denon: L’oeil de Napoléon, exh. cat., Paris: Musée du Louvre (Paris, 2000), 480.]  The “Vivant-Denon reliquary” is currently deposited in the Bertrand Museum of Châteauroux, and contains in the “right lateral compartment” a lock of Napoleon’s hair (two of which were used for mtDNA analysis. [2. Lucotte, et al. (2011) Haplogroup of the Y Chromosome of Napoleon the First. J. Mol. Biol. Research, 1:12-19.]  Also in the reliquary is three beard hairs belonging to Napoleon.

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Additional Native American Haplogroup Discovered by Genetic Genealogists

Robert Estes of DNAeXplain announces the discovery of a previously-undiscovered Native American haplogroup.  Up to the current point, research had found only two Y-DNA haplogroups in the Native peoples of North and South America – C3b and Q1a3a (aka Q1a3a1).  However,  new research described in the accompanying paper (here (pdf)) uncovers a third haplogroup found in Native peoples.

From the paper:

“For the past decade, since the advent of genetic genealogy, it has been accepted that subgroups of haplogroup C and Q were indicative of Native American ancestry. Specifically, subgroups C3b and Q1a3a, alone, are found among the Native peoples of North and South America. Other subgroups of haplogroup C and Q are found elsewhere in the world, not in North or South American, and conversely, C3b and Q1a3a are not found in other locations in the world. This makes it very easy to determine if your direct paternal ancestor was, or was not, Native American. Or so it seemed.”

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Sequencing the Genome of Sitting Bull and Other Famous People

ScienceNews reports that researchers led by Eske Willerslev at the University of Copenhagen are attempting to sequence the genome of legendary Native American “Sitting Bull” (see “Genome of a Chief”).

Earlier this year (2010), Eske Willersleve announced the successful sequencing of approximately 80% of the genome of “Inuk,” a man from Greenland who left behind a few small fragments of bone and four hairs frozen in permafrost when he died about 4,000 years ago (see “Long-Locked Genome of Ancient Man Sequenced”).  Using these ancient DNA sequencing techniques, Willersleve’s group is analyzing DNA from other samples.

One of these samples is a lock of hair from Sitting Bull.

Sitting Bull (c. 1831 – Dec. 15, 1890) was a Hunkpapa Lokota Sioux born in South Dakota.  Sitting Bull played an important role in the June 25, 1876 Battle of the Little Bighorn, and later toured as a performer in Buffalo Bill’s Wild West show.

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How Neanderthal Are You?

On May 6, 2010, the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany presented the world with a draft of the genome sequence of the Neanderthal (press release here (pdf) and full article here (free), NYT article here).  As part of the announcement, the team presented their conclusion that 1% to 4% of the genome of non-Africans is derived from Neanderthals:

“An initial comparison of the two sequences has brought some exciting discoveries to light. Contrary to the assumption of many researchers, it would appear that some Neandertals and early modern humans interbred. According to the researchers’ calculations, between one and four percent of the DNA of many humans living today originate from the Neandertal. ‘Those of us who live outside Africa carry a little Neandertal DNA in us,’ says Svante Pääbo.  Previous tests carried out on the DNA of Neandertal mitochondria, which represents just a tiny part of the whole genome, had not found any evidence of such interbreeding or ‘admixture.'”

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Faces of America and Genetic Genealogy Testing

Randy Seaver at Genea-Musings (“I’m Puzzled by DNA Claims on ‘Faces of America’”) writes about the fourth and last episode of “Faces of America,” a PBS documentary series investigating the ancestry of several famous people in America. This fourth episode included several different types of genetic genealogy to examine the ancestral origins and relatedness of the show’s members.

1. Whole Genome Sequencing by Knome

The first type of genetic genealogy was whole-genome sequencing by Knome of Henry Louis Gates and his father. This analysis examined Henry’s (“Skip’s”) genome for medical conditions and physical traits, and also compared his DNA to his father’s, thereby allowing them to deduce the entire DNA contribution from his deceased mother. This segment was actually quite moving, as Dr. Gates was able to establish this intimate connection to the mother that he and his father obviously missed very much.

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Q&A: Everyone Has Two Family Trees – A Genealogical Tree and a Genetic Tree

I recently received an interesting question from a reader (see this comment) about 23andMe’s Relative Finder, and thought it would be worth sharing the question and my answer with all my readers.

The Question:

I’m a man who recently took a 23andMe test, and I have a question about Relative Finder.  Another man who I match on 36 of 37 Y-DNA markers via Family Tree DNA also took a 23andMe test.  We believe that we are third cousins, but this individual does not show up as related in Relative Finder, nor does he show any similarities in the Family Inheritance section.  Does this mean that we are not related at all?

The Answer

If two individuals do not share any DNA in the Family Inheritance section of 23andMe or do not appear as relatives in Relative Finder, this absolutely does not mean that they are not or cannot be relatives.  It does suggest, however, that the two individuals might not share any DNA.  Although your Y-DNA test suggests that you share a recent common male ancestor, it appears that apart from your Y chromosomes you do not share any other DNA.

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23andMe’s Relative Finder Success Stories at ISOGG

ISOGG, the International Society of Genetic Genealogy, has a “Success Stories” page where it posts short summaries of just a few the many successes that genetic genealogy has helped people achieve.  Today I noticed that there are several new summaries regarding “Autosomal DNA Successes,” both of which were the result of 23andMe’s new Relative Finder (currently still in beta testing).

Relative Finder

As I recently wrote, Relative Finder is a feature at 23andMe that allows users to compare their autosomal DNA to the autosomal DNA of others to potentially find cousins.  This has long been done with Y-DNA and mtDNA, but this is one of the first times this has been done with autosomal DNA.

Success Story #1

The first success story is from someone who used Relative Finder to identify a huge number of potential cousins.  After connecting one of his or her potential 4th cousins, the individuals discovered that they have similar surnames from a certain location in common (in addition to DNA on chromosomes 3 and 10).  This individual also wisely noted that s/he now has “a good idea of the path that two of my DNA segments took through my pedigree to get to me.”  This is something I wrote about recently in “The Future of Genetic Genealogy – Tracing DNA To Individual Ancestors.”

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