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The Autosomal Me – Start, Stop, Go – Identifying Native Chromosome Segments

Roberta Estes

This is Part 7 of a multi-part series.

Part 1 was “The Autosomal Me – Unraveling Minority Admixture” and Part 2 was “The Autosomal Me – The Ancestors Speak.”  Part 1 discussed the technique we are going to use to unravel minority ancestry, and why it works.  Part two gave an example of the power of fragmented chromosomal mapping and the beauty of the results.

Part 3, “The Autosomal Me – Who Am I?,” reviewed using our pedigree charts to gauge expected results and how autosomal results are put into population buckets.  Part 4, “The Autosomal Me – Testing Company Results,” shows what to expect from all of the major testing companies, past and present, along with Dr. Doug McDonald’s analysis.  In Part 5, “The Autosomal Me – Rooting Around in the Weeds Using Third Party Tools,” we looked at 5 different third party tools and what they can tell us about our minority admixture that is not reported by the major testing companies because the segments are too small and fragmented.

In Part 6, “The Autosomal Me – DNA Analysis – Splitting Up” we began the analysis part of the data we’ve been gathering.   We looked at how to determine whether minority admixture on specific chromosomes came from which parent.

Part 7 – “The Autosomal Me – Start, Stop, Go – Identifying Native Chromosomal Segments”, takes a deeper dive and focusing on the two chromosomes with proven Native heritage, begins by comparing those chromosome segments using the 4 GedMatch admixture tools.  In addition, we’ll be extracting Native segment chromosomal start and stop addresses that we’ll be using in a future segment.

Using Doug McDonald’s tool and the 23andMe results, we can begin with the following two Native segments, one each on chromosome 1 and 2.  These will be our reference points, because according to both sources, these are the largest and most pronounced Native segments, the strongest indicators, so they will be our best yardsticks.

  Chromosome 1 Chromosome 2
23andMe

165,658,091 to 175,711,116

86,316,174 to 103,145,426
McDonald

165,000,000 to 180,000,000

90,000,000 to 105,000,000

On all of these admixture graphs, my results are shown first, then mother’s, then the comparison between the two where the colored regions show common ancestry and the black shows nonmatching segments – in other words those contributed by my father.

Please note that Native contribution in this analysis is being evaluated by a combination of geographies.  In some cases, one individual will show as “Native” meaning in the case of MDLP “North Amerindian” and the parent (or child) will show as something similar, like “Actic,” “South American” or “MesoAmerican.”  In order to normalize this, I have combined all of the geographies that are Native indicators.

MDLP

On the MDLP graph below, the legend indicates that these 4 regions are relevant to Native ancestry.

Chromosome 1 – Native Segment

On the graph below, you can see that mother has more grey than I do from about 162-165, but then I have some grey that she does not at about 170.

A detailed analysis of the segment of chromosome 1 between 158-173 shows the following admixture:

On my results, the putty green, MesoAmerican, is scattered between about 158 and 173, in three segments.  The putty green in my mother’s segments are from 159-160.5 and then 167-170.5.  Therefore, my father, by inference has a segment from about 162-165 and from about 170.5 to 173.

My teal, North Siberian, ranges from 162-163 and from 168-171.  My mother carries no teal in these segments, so this is inferred to be contributed from my father.

My dark grey, North Amerind, ranged from 162-165.5 and then from 168-169.5.  My mother’s range is from 161-165.5.  Therefore my grey segment at 168-169.5 is either recognized as MesoAmerican or Arctic Amerind in my mother.

Chromosome 2 – Native Segment

Chromosome 2 is quite interesting.  You can see that on my chromosome, the North Siberian begins at about 80.  Mom has none at that location.  My North Amerind begins at about 95 and extends to 105, where Mom’s begins in the same location but then transitions to a large segment of MesoAmerican which I do not carry.  I do have MesoAmerican, but mine begins about where hers ends and extends to about 105.  Mom’s North Amerind ends about 101, while mine continues to about 105.  She looks to have trace amounts beginning about 105 and extending through 115.

Eurogenes

The next graph shows the same chromosomes using Eurogenes.  Regions relevant to Native ancestry include:

Chromosome 1 – Native Segment

The difference between my chromosome 1 and my mother’s in this region is quite pronounced.  My mother’s is drenched in beautiful red South Asian, while I have absolutely none.  Some of the area where I have North Amerindian shows as South Asian on hers, but in other areas, there is no correlation.  It is expected of course, that there are areas where she has some ancestry and I have none, due to the fact that I only inherit half of her DNA, but she has a significant segment of East Asian between 163 and 164, and I look to have received only a very small portion.  The same is true of her Siberian segments at 163-164, but then I have Siberian that she does not at 169-170 and she has some that I don’t at 160-161.5.  Some of this difference can likely be explained, especially between the yellow North Amerindian and the red South Asian by slight differences in the DNA read and how it is categorized, but in other cases, the difference is real.  Looking at mother’s red segments from about 166.5 to about 168 and then looking at my corresponding region, you can see that I have nothing that hints at Native.  In that region, I clearly inherited from my father as well as my mother’s North European.

Chromosome 2 – Native Segment

As different as our chromosomes 1 were, one wouldn’t expect chromosome 2 to be so similar.  In the graph, I included my large South Asian segment surrounding 80, where Mom has a trace, although that is beyond the area indicated as Native by 23andMe and Doug McDonald.  In the range of interest, beginning at about 80, we find nothing until about 94 where mother and I both have North Amerindian segments that stretch through about 105.  Mom’s goes slightly further than mine, to about 105.5.  It’s interesting to note that in part of this region, on either side of 101, her Siberian and my North Amerindian are the same shape at the same location, so obviously the same DNA is being read and categorized as two different regions, probably due to my father’s admixture.

Dodecad

On the Dodecad graph of the Native segment, you can see the Native colors are in shades of green.

To use Dodecad in an equivalent manner as the rest of the tools, it looks like Northeast Asian is the closest we would get to Native American since that is where Native Americans lived just prior to crossing Beringia, so the greens should probably be evaluated as a group.  As can be seen on chromosome 1, they do clump together.  Even though West Asian is also found with this group, it seems to be outside the range, so I am not including it in the evaluation.

Chromosome 1 – Native Segment

You can see another example here of one segment being called South Asian in Mom’s and Northeast Asian in mine at about 170mb.

The Native, or in this case, Northeast Asian/Southeast Asian begins at about 162.5 where Mom’s and mine are very similar.  However, we diverge at about 164.5 where Mom begins with large segments of South Asian.  I have a little bit, but not much.  Beginning about 168, I have a large Northeast Asian segment, but she shows with South Asian there, although the segments are not exact.

Chromosome 2 – Native Segment

Chromsome 2 is quite simple using Dodecad.  Only two of the three groups appear.  Southeast Asian is absent, South Asian is present only in trace amounts except for one small area between 79.5 and 80 on my chromosome.  As expected, Northeast Asia is more prominent.  Mother has a few areas that I don’t, which is to be expected.

HarrappaWorld

Last, we have HarrappaWorld.  American and Beringian are the Native American categories here.  Regions relevant to Native American heritage would be:

Chromosome 1 – Native Segment

You can see both Beringian and American embedded again at about location 169.  In mine, this entire block reads as American.

There is one large chunk of Northeast Asian showing for both results, but part of that region of my chromosome, between 163-164 shows as American instead of Northeast Asian.  The Beringian is scattered through the American, which I would expect.  The American runs either strongly or weakly through this entire segment from 163 to 175 in mine or to 179 in mother’s.  Surprisingly there is no Siberian at all.  I would have expected to see Siberian before Northeast Asian.

Chromosome 2 – Native Segment

Where on chromosome 1, we saw no Siberian, on chromosome 2, we find Siberian instead of Northeast Asian.  I have no Beringian, but mother has 4 segments.  Three of her 4 segments are embedded with American segments.  Two may simply be categorized differently in my results, but two, I did not inherit.

Analysis Discussion

What have we learned?

When we are dealing with small amounts of minority admixture, they may or may not be able to be picked up directly by the testing companies.  Of course, part of this has to do with their thresholds for what is “real” and reportable, and what isn’t.  Aside from that, lack of identification of minority admixture probably has to do with which segments were inherited and their size, if they have been isolated and identified as Native by population geneticists, and the robustness of the data base sources the data is being compared against.

We can also see how difficult it is to sort through threshold matches, meaning what is Native, Asian, central Asian, etc.  Many of these differences are probably not actually differences between groups, but similarities with slight categorization differences.  Of course, it’s those differences we seek to identify our ancestral heritage.  Combining similar geographies may help reveal relationships masked my reporting and categorization differences.

Given that multiple sources have indicated Native ancestry, and on the same two chromosomes, I have no doubt that it exists.  Had any doubt remained, the exercises creating the MDLP Chromosome Map Table and reviewing the segments on chromosome 1 between 160 and 180mb would have removed any residual concerns.

The following table shows the results for the Native segments of chromosomes 1 and 2 beginning with the 23andMe and McDonald results, and adding the start and stop segments from each of the 4 admixture tools we used.

  Chromosome 1 Chromosome 2
23andMe

165,658,091 to 175,711,116

86,316,174 to 103,145,426
McDonald

165,000,000 to 180,000,000

90,000,000 to 105,000,000
MDLP

162,000,000 to 173,000,000

80,000,000 to 105,000,000
Eurogenes

162,500,000 to 171,500,000

79,000,000 to 105,000,000
Dodecad?

162,500,000 to 171,000,000

79,500,000 to 105,000,000
Harrappaworld

163,000,000 to 180,000,000

79,000,000 to 104,000,000
In Common

165,658,091 to 171,000,000

90,000,000 to 103,145,426

Although the start and end (or stop) segments vary a bit, all resources above confirm that the region on chromosome 1 between 165,658,091 and 171,000,000 is Native and on chromosome 2, between 90,000,000 and 103,145,426.  Those are the areas “in common” between all resources, which is shown in the last table entry.

The concept of “in common” is important, because while any one resource may report something differently, or not at all, when all or most of the resources report something the same way, it is less likely to be a fluke or reporting issue, and is much more likely to be real.  We’ll be using this methodology throughout the rest of the articles in “The Autosomal Me” series.

In the next segment, Part 8, we’ll be extracting the actual start and stop addresses of the Native only segments, referred to as the “Strong Native” method, and the combined Native indicator segments, referred to as the “Blended Asian” method and looking at how we can use those results.

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