Monday, July 1, 2013

Every Picture Tells a Story - Chromosome Painting

One of the things that has fascinated me right from the beginning was the mixed racial aspect of my Thacker branch of the family tree. But I am seven generations removed from David Thacker and his wife Sally Lemay Thacker.  Who knows how many generations the two of them were removed from their own non-European ancestors.

With each successive generation that married into European only families, my branch of the family lost all traces of their non-European heritage.  

So when the results of my DNA testing came back showing only European ethnicity I was not surprised – disappointed, yes, but not surprised. 

But what if lingering traces of my minority roots still remained in small segments? Segments so small that they didn’t show up in my overall ethnic mixture, but large enough to be recognized on the chromosomal level.  

That’s what the chromosomal painting features do at Gedmatch.  Simplified, your raw data is looked at and compared to the base data set, and based on those comparisons, the ethnicity of each segment of the chromosome is “painted” so you can “see” the different pieces of ethnic heritage.  

In my last post, I showed you my overall ethnic heritage according to Eurogenes K36 calculator.  Theoretically, I could use that same K36 calculator to paint my 22 pairs of chromosomes. The problems with doing that are twofold. 

1.    1.   It’s impossible for the computer to show 36 separate colors, and therefore the color red, for example, is used for Native American, Volga-Ural and Indo-Chinese.  Though  you can easily see red painted on a chromosome, you can’t be sure what the color means. 

2   2.  According to Gedmatch, there is a glitch in the program, and it can only paint up to 26 different ethnicities.  If you have a very diverse ethnic background, (over 26 of the listed ethnicities) you won’t get an accurate painting. 

So I picked Eurogene’s K12 to do my chromosome painting.  Here’s what is says about my overall admixture

South Asian                            1.00%
Caucasus                               2.98%
Southwest Asian                     2.60%
North American Indian &      
Mediterranean                        14.52%
East Asian                             
West African             
Volga-Ural                               8.63%
South Baltic                           15.43%
Western European                   28.41%

Here’s what the admixture looks like showing all 22 pairs of  painted chromosomes. 

The chromosomes are numbered left to right, and the segments run from bottom to top.  You can see that the majority of my chromosome are painted in the two hues of purple for Western European and North Sea.

My paternal grandmother’s family came to this country in 1906.  They came from a place called Pomerania, which is near the Baltic Sea.  Their contribution can clearly be seen in the deep blue portions of the painting. 

If my paternal grandfather had had his mitochondrial DNA tested, (he is a direct mitochondrial descendant from Frances J. Thacker) he like the other descendant of Frances J. Thacker we had tested, would have been found to have the U3a1 Haplogroup.  This particular haplogroup has its highest incidence in countries surrounding the Black Sea.  These countries would be found in the Caucasus, painted in Orange and the upper portion of the Southwest Asia area, painted in brown. 

But what I am really looking for are the American Indian segments (painted in Yellow) and the African segments (painted in mint green).  If I squint, I can make out a few tiny slivers of yellow and mint green on some of the chromosomes.  

My next post will take a look at these.



FEEDJIT Live Traffic Feed