DNA Analysis: Random is Most Important Factor

Correctly analyzing DNA matches for genetic genealogy is much harder than most researchers may think.

What is the most important thing to remember when interpreting DNA matches to determine relationships?

CC0 License, Debbie Parker Wayne, Random DNA Word Cloud

Researchers must remember that random recombination and mutations make it impossible to predict exactly how much DNA, if any, will be shared by two people, in general. The charts giving shared percentages of 50%, 25%, 12.5%, and so on are based on statistical probabilities. Real life seldom ever exactly matches a statistical probability. One exception is that each person does inherit one-half of the autosomal DNA from each parent.

Any reader of a mail list, forum, or Facebook will constantly see questions such as, "I share XYZ% of DNA with personXYZ. What relationship do we share?" And that reader will see tons of responses such as, "You must be XYZ relationship." The more savvy researchers will indicate there are several likely relationships and point to charts such as The Shared cM Project.¹ There are also some tools, such as the matrices on GEDmatch.com and the relationship predictions made by the testing companies, that use the statistical shared percentages to predict relationships.

Researchers must remember to use these predictions only as clues and not as a hard-and-fast limit to accurately analyze DNA findings.

The first chart below uses GEDmatch matrix tools to demonstrate how even full siblings can share widely varying amounts of DNA with a DNA match. Four full siblings are compared to a known fourth cousin. One sibling shares only 12.4 cM of atDNA, one shares 19.8 cM, one shares 50.2 cM, and one shares 52.1 cM. The second chart shows that the GEDmatch generations matrix tool predicting the number of generations between the test-takers varies from 4 to over 7. (GEDmatch changes the order of the siblings in the different matrix views.)

© 2017, Debbie Parker Wayne,
GEDmatch Shared atDNA Matrix, Siblings to 4C

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© 2017, Debbie Parker Wayne,
GEDmatch Generations Matrix, Siblings to 4C

Blaine published "The Shared cM Project" data using a Creative Commons License which gives permission for others to use and adapt the data as long as the adaptation is also made freely available and follows a few other restrictions.

Jonny Perl at DNA Painter adapted the data to create a Shared cM Project tool that highlights relationships that have been shown to share a specified amount of DNA. There are some differences in the highlighted relationships for 12.4 and 52.1 shared cM as shown in the images below.

CC0 License, Jonny Perl,
DNA Painter Shared cM Project Tool, Heading

CC0 License, Jonny Perl,
DNA Painter Shared cM Project Tool, 52.1 shared cM

CC0 License, Jonny Perl,
DNA Painter Shared cM Project Tool, 12.4 shared cM

The moral of the story is, as the Genetic Genealogy Standards indicate, there may be more than one way to interpret DNA test results:

19. Interpretation of DNA Test Results. Genealogists understand that there is frequently more than one possible interpretation of DNA test results. Sometimes, but not always, these possible explanations can be narrowed by additional testing and/or documentary genealogical research. Genealogists further understand that any analysis of DNA test results is necessarily dependent upon other information, including information from the tester, and that the analysis is only as reliable as the information upon which it is based.²

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1. Blaine T. Bettinger, "The Shared cM Project," The Genetic Genealogist (https://thegeneticgenealogist.com/). Search the blog posts for the most recent update to the project.
2. Genetic Genealogy Standards Committee, Genetic Genealogy Standards(http://www.geneticgenealogystandards.com/).

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To cite this blog post: Debbie Parker Wayne, "DNA Analysis: Random is Most Important Factor," Deb's Delvings, 9 October 2017 (http://debsdelvings.blogspot.com/ : accessed [date]).

© 2017, Debbie Parker Wayne, Certified Genealogist®, All Rights Reserved

Crowdfunding for 'A00 and the Peoples of Cameroon' Research Project'

Some of the technical advancements in our modern world amaze me.

In my DNA presentations I talk about how citizen scientists are contributing in a big way to new discoveries in genetics due to genetic genealogy projects. Last year a scientific paper was published that named a citizen-scientist, a genetic genealogist named Bonnie Schrack, as one of the co-authors. "An African American Paternal Lineage Adds an Extremely Ancient Root to the Human Y Chromosome Phylogenetic Tree" was published in The American Journal of Human Genetics.¹ When a member of Bonnie's DNA project did not match others in the project she investigated and got the Family Tree DNA (FTDNA) scientists involved. Long story short, new branches of the Y-DNA tree were discovered—the oldest branches of the Y-tree.

This is amazing because someone interested in his family history took a DNA test that revealed fascinating new information about the human family tree and a citizen-scientist made the initial discovery by comparing him to others in her project.

Now that citizen-scientist is using another modern technology, crowdfunding, to finance further testing to learn more about this new branch. In one day the project reached its initial goal. Don't let that prevent you from donating if you think this is as exciting as I do. Perhaps the project managers didn't have enough faith in the generosity of the genetic genealogy community to ask for all the money that will be needed for this project. They only asked for enough to get started so continued donations will be very much welcome and there will likely be later phases of fund raising as the project progresses. It costs a lot of money to travel around Cameroon to take DNA samples and pay for the kits.

Here is the announcement that Bonnie Schrack sent out earlier today on genetic genealogy mail lists (copied with permission, not cited as I saw it on a private list):

Dear friends and fellow enthusiasts,

I have an exciting announcement to share with you. Until now, we as genetic genealogists and researchers of deep ancestry have always been dependent on the field research carried out by professional, academic population geneticists, whose priorities and interests have been different from ours. They were the only ones with access to the grant funding necessary to finance such projects.

It's a new day now—the times they are a-changin'. "Crowdfunding" is one of the hottest new developments in the online world, and with good reason. Now, we the people can launch all kinds of projects, and we can decide what we want to support with our own funds.

Today we go live with our crowdfunding page for the first grassroots, citizen science organized project to collect DNA samples in the field, in Cameroon! We're using the Microryza website, which is devoted to crowdfunding science research. Here's the link:

http://microryza.com/projects/y-dna-a00-and-the-peoples-of-cameroon-in-search-of-the-homeland

OR

http://bit.ly/13Z3et8

Many of you heard about our discovery of the A00 haplogroup, the world's earliest-branching Y-chromosome lineage. It was found in a WTY[Walk the Y Project] of the [surname deleted], an African-American family with an extremely unusual and unique haplotype, and then we found a few haplotypes matching them from members of two African ethnic groups, the Mbo and the Bangwa, who are neighbors in Southwest Cameroon. A few tiny bits of Mbo DNA were shared with Dr. Michael Hammer, and sequenced by his lab and Thomas Krahn at FTDNA. The SNPs confirmed that they belonged to the same haplogroup as the Perry family.

Calculations by Dr. Fernando Mendez, and others in our community, have placed the branching age of this lineage at anywhere from 200,000 to 338,000 years ago—at the dawn of modern humans' emergence, or before. And so little is known about it! How far does it extend from those few Mbo and Bangwa families, and can it be found in other peoples? Is A00 a remnant of the earliest, indigenous hunting and gathering peoples of Africa, and if so, when and where were they assimilated into other peoples, who are now settled farmers (though they still hunt)?

For the first time since A00 has been known to exist, a young Cameroonian scholar, Matthew Fomine Forka Leypey, a member of the Mbo ethnic group, will visit the villages known to harbor significant numbers of A00 members, sample there, and collect information on the families. How do we know which villages have A00? Because Matthew collected the original Mbo samples, and over 2000 other DNA samples from all over Cameroon, as part of his dissertation research! His data indicate that the Mbo and Bangwa are only two of a number of peoples who have A00 among them. About a dozen other ethnic groups include A00 members, including some Pygmies! Those samples, though, are no longer available to us.

Now it's time to gather our own samples. We have a series of five field trips planned, to gather samples of diverse peoples in Western, Southern and Eastern Cameroon. Our analysis will include some special areas of knowledge from Matthew's studies, such as how different peoples support themselves within forest and grasslands ecologies, and the effects of polygamy vs. monogamy in patterns of populations' Y-chromosome DNA.

In the past, it has always been thought necessary to make DNA donors anonymous when they participate in scientific studies. In this project, however, we'll be asking for the donors' names, for several reasons:

1. We want to give them the possibility of receiving their test results, if they are interested
   
2. We want there to be a future possibility of families who match them, such as African Americans, to know their matches, if they opt in
   
3. We hope to gather a second sample (saliva) from one or more donors, in order to have a full Y genome sequence done
   
4. We hope to correlate the haplogroups and haplotypes we find with families of different known histories, such as royal lineages, traditional religious office-holders, and those that are known to have had ancestors held as slaves by local rulers.
   

Of course, their names will not be made public except, should they decide to participate and future funding allows it, to their individual DNA matches.

This is a kind of research, combining genealogy with population genetics, that academics rarely undertake, but which has been occasionally done in papers such as this one by one of the co-authors of our last paper, Dr. Krishna Veeramah:

"Sex-Specific Genetic Data Support One of Two Alternative Versions of the Foundation of the Ruling Dynasty of the Nso in Cameroon"

We have four weeks to raise the $2500 needed to launch our first field trip in Cameroon. Our deadline is August 19th. Then Matthew will set out for the remote mountain villages where he was raised. We look forward to bringing you all along on this great adventure.

In addition, apart from the appeal for fieldwork support per se, we're looking for a few generous individuals who'll help us obtain a decent (can be used) laptop and a digital camera for Matthew, who's a very low-income grad student. We're also looking for a trustworthy person flying to Cameroon who can take these along, saving us the exorbitant shipping fees. Please write to me if you have any leads.

In the near future, the next fundraising campaign will ask for your support for the DNA extraction and the screening of our first set of samples for A00. Stay tuned! Please visit and "like" our page on Facebook:
https://www.facebook.com/A00.Cameroon.Project

Looking forward to seeing you, with gratitude for your support,

Bonnie Schrack

If you can't afford to donate right now, but find this a worthwhile projec,t maybe you can help with the next round of fund raising. Go citizen-scientists!

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1. Fernando L. Mendez, Thomas Krahn, Bonnie Schrack, Astrid-Maria Krahn, Krishna R. Veeramah, August E. Woerner, Forka Leypey Mathew Fomine, Neil Bradman, Mark G. Thomas, Tatiana M. Karafet and Michael F. Hammer, "An African American Paternal Lineage Adds an Extremely Ancient Root to the Human Y Chromosome Phylogenetic Tree," The American Journal of Human Genetics 28 February 2013 (92:3):454-459; digital edition, doi:10.1016/j.ajhg.2013.02.002 (http://www.cell.com/AJHG/abstract/S0002-9297(13)00073-6 : accessed 22 July 2013).

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To cite this blog post:
Debbie Parker Wayne, "Crowdfunding for 'A00 and the Peoples of Cameroon' Research Project'," Deb's Delvings Blog, posted 22 July 2013 (http://debsdelvings.blogspot.com/ : accessed [date]).

© 2013, Debbie Parker Wayne, CG, CGL, All Rights Reserved