Using mtDNA for Genealogy: A Case Study – Comparing Results

Welcome to the fourth post of this series, where we get to the fun stuff – comparing results! In the first post, I introduced my 5th great grandmother, Charlotte Richardson and the two competing theories as to who her parents were.  In the second post, I outlined the process I followed to identify possible matches, in order to test the two theories. In the third post, I contacted female-line descendants and found one from each line who agreed to take the mtDNA test.

My results

To determine Charlotte Richardson’s haplogroup, along with the haplogroup of all of her children and her daughters’ children, and so on down the line, I tested myself. My mitochondrial DNA Haplogroup (which is also Charlotte’s) is…

My haplogroup

T2b. As well, I’m missing a mutation in the HVR2 region, which is the part tested with the mtDNA Plus test, and I have an extra mutation in the Coding Region, which is the part tested in the Full Sequence test. Note that I have a few other extra mutations, but when I did the Haplogroup Analysis at this site, it indicated that those mutations are on markers that occur too frequently or change too frequently to be relevant for determining ancestry, so they can safely be ignored.

T2 is a European Haplogroup – which was no surprise to me. While not as prominent as Haplogroup H, which is found in about 44% of the British population, it’s not a rare one either. About 6% of the population of England is Haplogroup T2.  It’s more predominant in the east of England. You can find more information on Haplogroup T2, along with a nice distribution map, at this site.

Theory 1: Mary Flintoff (possible mother) – Results

For Theory 1, I wasn’t able to get a descendant of Mary Flintoff to test, but a descendant of her sister Jane did agree. Pam’s results came back as…

Pam's haplogroup

U5.  No match.

So unless there’s a misattributed parentage somewhere, most of the people who have parents for Charlotte on Ancestry have it wrong. And since I’m also a descendant of Mary Flintoff’s son Joseph Richardson, it also means that I had two ancestors with the same last name, who lived in the same area, born 3 years apart, who were not siblings, and likely not related at all!

Theory 2: Barbara Richardson (possible sister) – Results

So what about Theory 2? My tester for Theory 2 was Don, a descendant of Barbara Richardson. Don’s initial results came back as….

Don's basic haplogroup

T2! As well, he was missing the same mutation I was, so that was a promising sign. But since the Coding Region is only tested with the Full Sequence test, the results were not yet conclusive. As I mentioned earlier, 6 percent of the British population are T2. And it’s even higher in other parts of Europe, so we could be the same haplogroup without having a recent common ancestor.

I ordered the upgrade, and waited again. Fortunately, those results didn’t take long to process. A couple of weeks later, I got notification that his full sequence results were in.

Don's full haplogroup

Well would you look at that! Don is also T2b. He also has the same extra mutation that I have. Plus, he has another one. What does that mean? Are we a match, or not?

To put these results in context, let’s look at all of my matches

My Matches

As of today, I have 539 matches. Of those, 191 are at a genetic distance of 2 (meaning that we have two differences) and 340 are a genetic distance of 3 (meaning we have 3 differences). I have a common ancestor with all these people, but it could be REALLY far back.

mtDNA matches

I have only one perfect match (genetic distance of 0) – a woman named Alana from New Zealand. We are both T2b, plus we’re missing the same mutation (C195T) and we have the same extra mutation (A7374G). Her most distant known ancestor on her maternal line was born in 1796 (20 years after Charlotte) in West Sussex, England.

I also have seven matches with a genetic distance of 1, some of whom I’ve been in contact with. Six of the seven are all GD0 to each other. They are all missing the C195T mutation, but none of them have the A7374G mutation that Alana and I have.  So again, we definitely have a common ancestor, but it’s hard to say how far back. That all depends on how long ago our 7374 changed from an A to a G.

And then there’s Don. He’s also a genetic distance of 1 to me, but for a different reason than the the other six people at GD1. Don is genetic distance 1 to me because he has an extra mutation that I don’t have.

Do you notice anything odd about Don’s extra mutation? It ends with a “D”. One of the first things I learned about DNA is that it can be one of 4 letters – A, T, C, or G. So what does “D” mean, you may ask? I know I sure did! That’s what’s called a “heteroplasmy”

[Note: See Debbie Kennett’s comment – Don’s extra mutation is a deletion, not a heteroplasmy. I’ll update soon with the correct information]


When they test your sample, they test many different cells. Usually, each of the cells has the same result for the same gene. But sometimes, it does not.

According to the chart on the Family Tree DNA Learning Centre, D means samples of that gene showed up as A in some cells, G in others and T in others.


For my purposes, the most interesting bit about Don’s mutation being a heteroplasmy is that a heteroplasmy is usually a recent mutation – within the past 3 to 5 generations. Since our common ancestor would be 6 generations back for Don, it is most likely that his mutation occurred more recently than that, and our suspected common ancestor is indeed our common ancestor.

Possible outcomes revisited

In the first post in this series, I identified four possible outcomes:

Possible outcomes - detailed

A match between Don and I indicates that Charlotte Richardson and Barbara Richardson were sisters (or another maternal relationship, but given they have the same last name, sisters is the most likely relationship). And unless their parents were on Prince Edward Island, left and then returned, which is unlikely, we’re looking for parents who were on PEI, probably in Charlottetown, for at least a 6 years span – 1776 to 1782.

The question I most wanted to answer – who were Charlotte Richardson’s parents – remains unanswered. But knowing that Charlotte and Barbara were sisters gives us some very important clues.

In the fifth and final post of this series, I will discuss what this discovery has meant for the search for Charlotte’s parents, and give some final thoughts on the use of mtDNA for genealogy.


2 thoughts on “Using mtDNA for Genealogy: A Case Study – Comparing Results”

  1. Thank you for sharing your excellent case study. I think you will find the extra mutation that Don has is in fact a deletion rather than a heteroplasmy. Deletions are normally written with a lower case d. There is an explanation in the FTDNA Learning Center but for some reason they use an upper case D in their example: If you switch over and look at Don’s sequence using the CRS (Cambridge Reference Sequence) I think you’ll find that the mutation will be written as 15944-. I don’t this difference will affect your conclusion.


    1. Hi Debbie. Thanks for your comment! Indeed, I looked at his sequence in CRS and it is written 15944-. I’ll do some reading on deletions and then update the post accordingly. Thanks for bringing this to my attention – much appreciated!

      Liked by 1 person

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