Tuesday, March 12, 2013

My 23andMe Test Results - Post 2: Chromosome Views UPDATED!

I received my 23andMe.com genetic test results last week, and described the results in "macro" terms in My 23andMe DNA Test Results - Post 1:  Ancestry Composition (5 March 2013).

I've been checking out everything in the autosomal test results pages, and have discovered several features that are very useful and interesting.  I've started speculating how some of the more confusing DNA segments got into my autosomal DNA results.

What I know about my ancestral families, based on my 64 4th great-grandparents, is:

A)  Father's ancestry:

*  Colonial Massachusetts: 24 of 32, all of English ancestry in the 1600s (no known Irish or Scottish)
*  England: 8 of 32, all in Wiltshire in the 1600s, 1700s, and early 1800s

B)  Mother's ancestry:

*  Colonial US English: 13 of 32, in the US in the 1700s, of English ancestry in the 1600s (perhaps 1 known Scots-Irish)
*  Colonial US German: 15 of 32, in the US in the 1700s, of German ancestry in the 1600s (1 known Dutch)
*  Colonial Canada: 2 of 32, of unknown ancestry in the 1700s (perhaps French)
*  England: 2 of 32, all in Somerset in the 1600s, 1700s and early 1800s

The Ancestry Composition page says:

"Ancestry Composition tells you what percent of your DNA comes from each of 22 populations worldwide. The analysis includes DNA you received from all of your ancestors, on both sides of your family. The results reflect where your ancestors lived 500 years ago, before ocean-crossing ships and airplanes came on the scene."

Here is my Ancestry Composition chart (with the Standard Estimate.  There is also a Conservative Estimate and a Speculative Estimate available):

As you can see, I'm 99.3% European, and 0.6% East Asian and Native American. In the chart above, there are 23 sets of lines - one for each chromosome.  For chromosomes 1 to 22, my mother's contribution is above my father's contribution.  The X chromosome is my mother's, since I am a male person.

UPDATED:  1:30 p.m.:  Blaine Bettinger on Facebook and Brian in comments told me that my "assumption" that the top line is my mother's and the bottom line is my father's is wrong...thank you, guys!  Brian noted that the FAQ for Ancestry Composition says:  "Genotyping chips like the one 23andMe uses don't capture the information about which markers came from which parent." That changes things further down!

The above chart is somewhat difficult to sort out, at least for the European sub-groups. However, I found that by running my mouse over the list on the right for each reference population, I could see the segments on the chromosomes contributed from that population.  For instance, I ran my mouse over the Northern European portion and the chart highlighted the segments on the chromosomes that were from Northern Europe:

Here are the British and Irish segments on the chromosomes:

The French and German segments are in the next chart below:

The Scandinavian segments are shown below:

The Southern European segments are:

The East Asian and Native American segments are below:

I've also looked at the "Speculative Estimate" which assigns higher percentages to some of the Northern European ancestry.

I have several surprise in these charts, including (I'm going to leave these here in spite of my assumption error noted in the update...take them with a grain of salt!):

1)  My father has a large segment of German and French DNA on Chromosome 1, and smaller segments on Chromosomes 1 and 17.  I have no clue where that comes from; my speculation is that 500 years ago, some French or German folks had migrated to England.  My English ancestry is from all over England, including areas settled by Normans and Saxons and Angles, plus the folks who had lived in England for thousands of years.

2)  My father has a significant segment of Scandinavian DNA on Chromosome 3, and that is the only Scandinavian segment in my tested DNA.  Again, I don't have any known ancestry from Scandinavia on my father's side (I do on my mother's side!).  My speculation is that this may be one or more ancestors descended from Scandinavia who migrated to the British Isles before 1600.

3)  My father has the only segment from Southern Europe on Chromosome 22.  My speculation is that this may be from Iberia or Italy, and may be a vestige from Roman times in England.  

Interestingly, there are more segments for my father's German and French, Scandinavia and Southern Europe in the "Speculative Estimate."

4)  My mother has a segment for East Asian and Native American DNA on Chromosome 12.  I don't know for sure where that comes from.  My speculation is that this may be from the wife of Abraham James Kemp, who is identified in a Bible record transcript as Sarah Sephrona Fletcher, of French-Canadian heritage.  There may be (or may not be!) a Native American ancestor in her ancestry.  I probably have other candidates who might have had a Native American ancestor, since quite a few of my ancestors lived on the English/Native frontier in the mid-1700s.  This is about 1/167th of my DNA, so it probably occurs in the 7th or 8th generation back).  

5)  My mother has a long segment of French and German DNA on Chromosome 2, and shorter segments on Chromosomes 7 and 12.  I am surprised that there is so little identified here because of her known 15 of 32 ancestors from German ancestor.  There are many more segments identifying as French and German in the "Speculative Estimate" chart.

Here is the "Speculative Estimate" chart (you change this in the upper right corner of this web page, next to your name):

My "Speculative Estimate" breakdown for the reference populations are:

*  99.4% European

** 43.0% British and Irish
** 25.2% French and German
** 2.7% Scandinavian
** 0.0% Finnish
** 26.1% Nonspecific Northern European
**  0.4% Iberian
** 0.0% Sardinian
** 0.0% Italian
** 0.0%  Balkan
** 1.2% Nonspecific Southern European
** < 0.1% Ashkenazi
** 0.0% Eastern European
0.7% Nonspecific European

*  0.6% East Asian and Native European

** 0.6% Native American
** 0.0% East Asian
** 0.0% Nonspecific East Asian & Native America

I hope that I can have CeCe Moore analyze my autosomal DNA results at the upcoming Chula Vista Genealogical Society seminar on 30 March 2013.

The URL for this post is:  http://www.geneamusings.com/2013/03/my-23andme-test-results-post-2.html

Copyright (c) 2013, Randall J. Seaver


Brian said...

I wasn't aware that the Chromosome lines were broken down between mother and father on that chart. I thought at least one parent's test was required for that.

Where did you see that info? That would definitely help me narrow a few things down.

Brian said...

For example, I saw this is one of their FAQs on the Composition: "Genotyping chips like the one 23andMe uses don't capture the information about which markers came from which parent."

Charles said...

I had my mother and maternal grandmother tested at 23andme. Based on comparing my DNA in chromosme view against my mother, the segments that appear to match (I have distinctly mixed ancestry) with her are on the top. For my mom and grandma, their matches seem to be on the bottom row of my mother's view.

My wife and father-in-law have tested as well. Her matching segments with him appear to always be on the top row for her.

We will have my father, paternal grandmother, mother-in-law, and a few aunts/uncles/cousins tested soon as well but I get the feeling the trend will be the same: for men, maternal DNA is in the top row and for women on the bottom.

Penelope said...

I have just had a very unpleasant two person flame war with a woman that seems to think that one 23 and me test taken by her and one by a half sib (different father) gives her enough information to "look at chromosomes" from her mother's side and her father's side. Her father is unknown and obviously, untested. I understand that she is rather desperate to identify her father, but I don't see that there is enough genetic "material" here to go "off" on me and my poor little aged genetics degree. I have tried to keep up, but did I miss something? I was trying to help.

Charles said...

After receiving results back for my father and his mother, i can comfirm the trend from my previous post holds true.

If a parent is tested and that test is linked appropriately on your tree, the composition results will be phased and the chromosome breakdown should be more representative of the DNA you inherited by parent. There are some instances on my parents chomosome view in which particular segments do not map to their mother's according to the trend I mentioned.

After the composistion results were phased, there were some segments that were moved from top to bottom and vice versa on several chromosomes.

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