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About mtDNA

female symbols

This page is about mtDNA and its use in genetic genealogy.

Other References

The Concept

mtDNA is the DNA (dioxy-ribonucleic acid) within a mitochondrion (plural, mitochondria). The mtDNA genome is not the same as the genome within the cell nucleus. Mitochondria are structures ("organelles") within cells -- outside the nucleus -- acting as "cellular power plants"; they generate most of the cell's ATP supply, a source of chemical energy. Each mitochondrion contains several copies of a single chromosome or genome.

Mitochondrial DNA en
mtDNA genome, from Wikipedia

Both males and females have them -- because they're essential to cell life -- but they're inherited only from mothers. The mitochondria are contained within the mother's egg.

mtDNA is passed down, from mothers to their sons and daughters, almost without change for many generations. It follows only the direct & unbroken maternal line. It says nothing about male ancestors. Picture a pedigree chart, where fathers are represented above mothers: mtDNA traces the bottom line of the chart.

It is even more stable (less subject to mutation) than Y-DNA, making it useful in studies of population genetics and evolutionary biology. On the other hand, this stability gives mtDNA a very long time view.

However,

The mtDNA test differs from the Y-DNA STR test in being much less specific as to maternal lineages. (It is roughly analogous to early Y-SNP tests in specificity.) This is due to the mitochondrial genome being much more stable (less subject to mutations) than the Y chromosome.

Your results will classify you into one of many haplogroups, a broad category of people sharing ancient maternal ancestors. The most recent common ancestor may be thousands of years in the past.

 
mtDNA Phylogenetic Tree, showing only major branches

Primarily, the mtDNA test is about deep ancestry, not documentable genealogy. Only the Full Genomic Sequence (FGS) yields a reasonable probability of a match indicating a common ancestor within genealogic time.

mt Quick Facts

mtDNA and Taylor Family Genes

At this time, mtDNA is a limited activity of the Taylor Family Genes project;  it has only weak association with the surname. If your mother's maiden name was Taylor, her mother's maiden name was probably not Taylor.

We group members by mtDNA haplogroup; see our mtDNA results. We do not analyze matches, determine genetic families or publish maternal lineages.

Taylor mtDNA Haplogroups

Mitochondrial haplogroups in the project show a variety similar to Y- haplogroups,

Taylor mt Haplogroups
Hgrp Pct.   Hgrp Pct.
H   31% W   3%
U 13% C 2%
K 12% V 2%
T 12% X 2%
J 8% A  1%
L 6% D 0.5%
HV 3% N 0.5%

The Test

The testing process is user-friendly. Swab the inside of your cheek with a brush-like device or Q-tip provided by the testing company to get a sample; this collects skin cells from inside your mouth. Place the swab brush in the sterile container provided and mail it back to the testing company's laboratory in the mailing container also provided.

In a few weeks, the laboratory will have done its highly-technical thing, analyzed the mtDNA & notified you of the results. These results represent .

Who can test?

Anyone. Both women and men can take a mtDNA test.

How much Test?

Members & prospective members often ask us which of the tests they should order. Cost is a consideration, because fuller coverage cost more than those with less.

Levels of testing available

The tests vary by how much of the mt genome is analyzed:

Your results will list the SNPs (single-nucleotide polymorphisms) which differ from the reference sequence being used.

What is the recommended minimum?

The project makes no recommendation as to the level of testing.

What do I get?

You will receive several services and pieces of information from your test.

  1. The ability to log onto your personal My FTDNA pages at www.familytreedna.com.
  2. A description of your differences from a reference sequence, which will look something like the example below

    The number of SNPs listed will depend on your order and the SNP values will probably be different.

  3. A determination of your haplogroup; the determination becomes more precise as testing level increases.
  4. Excellent after-market customer service.
  5. The ability to search the FTDNA database for close matches to you.
  6. Access to FTDNA tools and information for interpreting your matches.
  7. The services of a DNA project to help you through the process.

Many testing companies provide only two or two and a half items listed above.

The Results

You'll receive a certificate of the results and a and report describing the testing process. For STR testing (the most commonly used), the certificate will have a list of differences from the RSRS and RCRS.

Typical mtDNA Results
DIFFERENCES FROM RSRS
HVR1 HVR2
  • A16129G
  • C16179T
  • T16187C
  • C16189T
  • T16223C
  • G16230A
  • T16278C
  • C16311T
  • T16356C
  • C146T
  • C152T
  • A247G
  • 315.1C
  • G499A
  • 522.1A
  • 522.2C
  • 522.3A
  • 522.4C

What the results mean

Mitochondrial DNA results describe differences from a reference sequence. These differences are described in terms of where they are (positions) on the genome and how they differ.

In the RSRS system, the first letter indicates the type of base (A, T, C, or G) in the ancestral haplotype. The final letter indicates the base which replaced it and the numbers in between indicate the position on the genome. For example, "A16129G" means that an A (adenine) at position 16129 has been replaced by a G (guanine).

Obviously, that's esoteric stuff and fairly meaningless, except in comparison to other people's results. Do they or don't they have A16129G? And, all your other differences?

Reference Sequences

Three reference sequences are used in interpreting mtDNA results:

Effect of Reference Systems on Tree

As a result of the starting point and the irregular nature of subsequent discoveries, mtDNA haplogroups do not begin with A and proceed through the alphabet to reflect human evolution. The mt phylogenetic tree begins with L -- of which one branch, L3, gave rise to most of the other haplogroups found today.

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Matches

Most who test are interested in finding matches with others who may share the same maternal lineage.

What is a "match"?

A "match" exists when two (or more) haplotypes are sufficiently similar; they agree enough to indicate that they share a common maternal ancestor. In general, the more SNPs that agree, the more likely it is that two people share a common maternal ancestor and the more likely that this ancestor is more recent.

Purpose

The purpose of match interpretation is to decide whether a found match is worth pursuing. Does it warrant the hard, slogging documentary research needed to identify the MRCA by name, dates, places and other specifics?

Match Interpretation

FTDNA gives this guide:

Testing Level Matching Level Generations to MRCA
50% Confidence* 95% Confidence
mtDNA HVR1 1 to 52 N/A
mtDNAPlus HVR1 & HVR2 1 to 28 N/A
mtFullSequence HVR1, HVR2 & Coding Region
{Complete mtDNA genome}
1 to 5 1 to 22
Notes:

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Haplogroups

A haplogroup is a broad category of haplotypes sharing similar origins & characteristics. A haplotype is a unique DNA pattern but two or more haplotypes may be sufficiently similar to be grouped together,

A haplogroup identifies broad groups of different strains of mtDNA -- main branches on the human family tree. Because haplogroups are associated with particular places, this tells you something (e.g., ethnicity & geographical origin) about your distant maternal forebears who are otherwise lost in the mists of time before recorded history. A haplogroup determination speaks to deep ancestry; it is less useful within genealogic time.

A haplogroup designation starts with a capital letter, which may be followed by alternating numbers or letters, e.g., "L3'4" or "J1b1b".

Haplogroups for mtDNA are named in the order they were identified, not in the order of origin. The oldest mtDNA haplogroup (mitochondrial "Eve") is L; it is thought to be 190-200 thousand years old. The most common haplogroup in Europe is H and its subclades, which reach frequencies of about 41%; it's thought to have originated 20-25 thousand years ago. It is also the most common in Taylor Family Genes.


Frequencies of mtDNA haplogroups in Taylor Family Genes.

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mtDNA Tree

The mtDNA tree starts with haplogroup L, considered to be that of the "mitochondrial Eve". Other human females were probably living at that time (140-200 kya) but did not produce a direct and unbroken maternal lineage to persons alive today. Branches of L include L0 through L6 and every other haplogroup.

MtDNA Haplogroups
Haplo
group
From Origin Comments
Time (kya) Place
L ? 140-200 East Africa Base
M L3 60 South Asia or Africa "Out of Africa"
C CZ ← M8 <60 Central Asia  
Z CZ ← M8 <60 Central Asia  
E M9 16-39 Indonesia or Taiwan  
G M 36 East Asia  
Q M 50 East Asia Oceania
D M 40-60 East Asia Northeast Asia
N L3 71 Asia or East Africa Europe & Oceania
I N1 17-24 West Asia Very low frequencies
Europe, West Asia
& South Asia
W N2 24 West Asia  
Y N9 12-33 Asia NE Asia
A N 30-50 Asia Native American
S N ? ?  
X N 30 West Asia Widely dispersed,
low frequencies
R N 66 South Asia Widespread
HV R0 25-30 Near East
or Caucasus
West Eurasian
H HV 20-25 Southwest Asia 41% of Europeans
V HV0a 10 Near East 59% of Saami
J JT ← R 46 Caucasus,
Near East
12% of Europeans
T JT ← R 20-30 Fertile Crescent Eurasian
F R9 43 Asia  
B R11 50 Southeast Asia "Ina"
P R 50 Southeast Asia Indigenous Australians
U R 55 ? 11% of Europeans
K U8b 23-40 Western Asia 10% of Europeans
O ? ? ? Australia and Oceania


Graphic cladogram by John S. Walden; original at http://freepages.genealogy.rootsweb.ancestry.com/~jswdna/

American Indian Haplogroups

Certain mtDNA haplogroups are considered to be characteristic of Native Americans, though they may also be found in Asia. These are subclades of the macro-haplogroups A, B, C, D and X.

For more detail, see Roberta Est5es' blog on the subject.

Glossary, Definitions

Due to the amount of content, we've moved this section to a "glossary" page. If the definitions in the list do not display, click here.

 

Projects

Membership in a surname project is less beneficial for mtDNA than for Y-DNA. Maternal surnames tend to change with each generation, so the association with any particular surname is weak.

But, membership in geographical and haplogroup projects may be as beneficial as for Y-DNA.

mtDNA Facts

cell bodies diagram

The "mt" stands for mitochondria (singular = mitochondrion, adjective = mitochondrial). Their name comes from the Greek mitos for thread and chondrion for granule.

There are hundreds of them in each of our cells. They are not, however, part of the cell nucleus and are unrelated to the 23 pairs of chromosomes in "nuclear DNA". As they are contained within the mother's egg, they are inherited maternally. Their DNA is very stable, but lacks a repair mechanism.

Their abundance has proved invaluable in paleontological studies of human DNA, making it much easier to reconstruct mtDNA from ancient remains than nuclear DNA. As a result, we know more about early women than early men. For example, http://dna-explained.com/2014/06/09/dna-analysis-of-8000-year-old-bones-allows-peek-into-the-neolithic/.

Mitochondrial existence was discovered in the 1960s by two teams working independently:

Mitochondria are theorized to have been -- at some point in our evolutionary development -- separate, symbiotic organisms which were eventually absorbed into the cells. It is called the endosymbiotic theory; there has been no evidence to support or refute it.


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Revised: 18 Oct 2014