Questions and answers about mitochondrial DNA
Q. So why an mtDNA Q&A today anyway?
A. Because there’s a major sale going on — a March Madness sale — at Family Tree DNA that ends at 11:59 p.m. CDT on Tuesday, April 1, that offers real savings on one test and one test only: the full mitochondrial (mtDNA) sequence.
Q. Um… what’s mtDNA?
A. That’s the type of DNA passed down from a mother to all of her children, but that only her daughters can pass on. a particular type of DNA that everyone has, passed to us from our mothers. Because of the way it’s inherited, all of a mother’s children will have the same mtDNA, but only her daughters will pass it on to their children. So it gives us a look at our maternal line: our mother’s mother’s mother’s line and on back through the generations.1
Q. Can you show me that a little better?
A. Yep: look at this chart. Figure you’re one of the folks in red at the bottom — male or female, since we all have mtDNA — and trace it back: it looks at our mother’s mother’s mother’s line and on back through the generations.
Q. How many markers does this test look at? 25? 37?
A. Those are the numbers for the guys’ test — the YDNA test. Mitochondrial DNA isn’t measured that way. For mtDNA you look at either part of the mtDNA (specifically in areas called hypervariable regions, or HVR1 and HVR2) or all of the mtDNA (HVR1 plus HVR2 and the coding region).2
Q. Which test is on sale?
A. The “whole thing” test: the full mitochondrial sequence looks at HVR1 and HVR2 and the coding region.
Q. And that will tell me…?
A. Everything you can know about your mtDNA: your haplogroup like A or H or K or U, plus how your own personal mtDNA differs from a reference mtDNA in ways that make you different from other folks who are not genetically related to you and similar to other folks who are genetically related to you.
Q. What’s a haplogroup?
A. Technically, it’s “a genetic population group of people who share a common ancestor on the patrilineal or matrilineal line.”3 Think of it like your town sitting somewhere in the branches of the human family tree. Since we’re looking at the matilineal line with this test, everybody in that town with you came from the same area — the same common mother back thousands of years ago.
Q. What does that do for my genealogy?
A. It’s really a matter of seeing what it might do. No DNA test comes with guarantees. But let’s say you have a family story that your maternal grandmother or great grandmother was Native American. It might confirm that story. Or it might tell you that your mother’s line is strongly European — so you don’t waste time chasing a Native American story in that particular line. (It could be a maternal great grandfather, not great grandmother, still.)
Q. What about the individual results — those people you say I’m genetically related to — how does that help?
A. Finding out you and someone else are — or aren’t — related in a direct maternal line can answer some pretty big brickwall questions. I’ve written about some of these issues in my own family4 and in questions from readers.5 And yesterday’s blog by Roberta Estes at DNAeXplained is a must-read for anybody who wants to know why to mtDNA test.6
Q. Should I test myself or my mother or my brother?
A. I’d always test the oldest available generation — mother before child, grandmother before mother — mostly because I’m always thinking about other later DNA tests I might be able to afford, and an older generation is always better for an autosomal DNA test.
Q. Only my brother and I are available to test. Which of us is best?
A. In most cases, both of you will have exactly the same mtDNA as each other — and exactly the same as your mother had, and her mother, and her mother. But remember — even though mtDNA changes slowly — that small change can happen any time in any generation. I’m aware of one case where a change occurred when mtDNA was passed from a mother to one of her children. So in most cases it won’t matter which of you is tested for mtDNA purposes, but boy… if you can afford to test both of you, that’s the way to go. Then later you can do a YDNA test for him (getting information on your father’s father’s line)7 and autosomal testing on both of you (to find cousins alive today).8
Q. Back to this sale thing, what’s the difference between an add-on and a new kit?
A. An add-on means you’re already a Family Tree DNA customer but have never done mtDNA testing. A new kit means you’re not yet a Family Tree DNA customer.
Q. How much can I save?
A. You can save about a third on the cost of this test. Full price is usually $199, and the sale price is $139 — a $60 savings.
Q. Why can’t I get the cheaper upgrade test?
A. You can — if you’ve already done some mtDNA testing at Family Tree DNA and want more information. If you’ve tested only the HVR1 region, you can upgrade for $99, down from the regular $149. If you’ve tested both HVR1 and HVR2, the upgrade is $89.
Q. How many kits can I buy?
A. How many can you afford — and realistically how many people do you want to test?
Q. Are any other tests on sale?
A. Not in this sale, but check back from time to time: Family Tree DNA runs sales three or four times a year.
Q. How do I find out more?
A. Head on over to Family Tree DNA.
- See ISOGG Wiki (http://www.isogg.org/wiki), “Mitochondrial DNA tests,” rev. 5 Mar 2014. ↩
- Ibid. ↩
- ISOGG Wiki (http://www.isogg.org/wiki), “Haplogroup,” rev. 4 Mar 2014. ↩
- See Judy G. Russell, “Oh, mama… a use for mtDNA,” The Legal Genealogist, posted 12 Feb 2012 (http://www.legalgenealogist.com/blog : accessed 27 Mar 2014). Also, “Looking for an Alabama relative,” posted 1 July 2012. ↩
- Judy G. Russell, “DNA and the question of how many wives,” The Legal Genealogist, posted 8 July 2012 (http://www.legalgenealogist.com/blog : accessed 27 Mar 2014). ↩
- Roberta Estes, “Mitochondrial – the Maligned DNA,” DNAeXplained, posted 29 Mar 2014 (http://dna-explained.com : accessed 29 Mar 2014). ↩
- See ISOGG Wiki (http://www.isogg.org/wiki), “Y chromosome DNA tests,” rev. 5 Mar 2014. ↩
- ISOGG Wiki (http://www.isogg.org/wiki), “Autosomal DNA,” rev. 1 Feb 2014. ↩