mtDNA

The basic science:

  • The mtDNA test can be used for testing females or males, but only females can pass their mtDNA on to their children.
  • The mtDNA test uses information from the mitochondria, which is the material that surrounds the chromosomes. mtDNA is passed from a mother to her children, essentially unchanged. (If there were no changes, each person would have exactly the same mtDNA as "Eve" and with each other.)
  • This test is only useful in testing the participant's mother's mother's .... mother's line. As this line changes names every generation, it is relatively difficult to track more than a few generations through genealogy.
  • All people who share the same "common ancestor" will carry essentially the same mtDNA and receive tests results that are also essentially the same.

Haplogroups:

  • Fortunately, there are random and subtle changes that allow us to see differences in different "genetic families".
  • Using these differences, scientists have been able to group all people into major branches called "Haplogroups"
  • These can be arranged into a "family tree of woman" that shows the different branches that have separated over 1000s and 10,000s of years.
  • Each person today can be assigned to a Haplogroup, which tells her (or him) their "deep ancestry". Haplogroup are determined by looking at mutations.

Mutations:

  • mtDNA is passed from mother to child "essentially unchanged". However, on a random, but predictable basis for a large group, minor changes occur that we call "mutations".
  • We cannot predict when these mutations will occur in an individual family, but we do know that a mutation that occurs in one woman will be passed on to her children - and that her daughter will pass it on to their children, and so on ....
  • These mutations have occurred through the centuries, giving us the Haplogroups mentioned above,
  • These mutations occur less frequently than in yDNA, which makes them less useful in genealogy.
  • Our genealogical paper trails usually extend a few hundred years on our maternal line, with a fortunate minority having paper trails reaching back further.
  • Many people carry mtDNA which has not experienced a mutation in the past 1000 years. Still, by comparing results, we can draw conclusions on which maternal lines share a common ancestor.

Results:

  • The results are generated by examining the mitochondria and comparing it to the standard reference first created at Cambridge that is used world-wide.
  • The results are typically reported by designating only the differences to the Cambridge Reference Standard.
  • Scientists have identified specific mutations as key to defining the haplotype, and then the sub-haplotype, often called the clade. Further mutations in the result are considered to have occurred later. As example, the author's mtDNA is classified as Haplogroup T, then subdivided into group 1, and further into subgroup a. This is written T1a.

Test Options:

  • you can be tested at different "resolution" levels. These vary slightly from one testing company to the next in cost and in which specific addresses are examined. This explanation is for Family Tree DNA (FTDNA), the testing company that World Families Network recommends.