Wednesday, March 26, 2014

Understanding mtDNA

Photo From Maternal Ancestry Store, Genebase
HVR1 and HVR2 Results

Over and over the a3Genealogy DNA team are asked if mtDNA and X chromosome are the same. Simply, the answer is no. Yet, the mitochondrial DNA , carried down the female line to her children (sons and daughters), is passed from mothers and contributes to the X chromosome path. Sons, do not pass mtDNA. 
What Can Be Gleened from the mtDNA Tests?
mtDNA covers the hyper-variable regions of the genome and covers both recent and distant generations : 1) HVR1 (16024-16569) produces large number of matches 2) HVR2 (00001-00576) test results combined with HVR1 assists in identifying maternal ethnic and geographic origin, haplogroup. But genealogical gains are limited:
  • Matching on HVR1 means that you have a 50% chance of sharing a common maternal ancestor within the last fifty-two generations. That is about 1,300 years. (1)
  • Matching on HVR1 and HVR2 means that you have a 50% chance of sharing a common maternal ancestor within the last twenty-eight generations. That is about 700 years. (1)
If you want the possibility to match common recent ancestors, consider a "full sequence" mtDNA test by adding the Coding region 00577-16023, the entire mitochondrial genome. Compared to the HVR1 and HRV2 testing, "a perfect match of a full sequence test indicates a common ancestor in recent times" (2)
  • Matching on the Mitochondrial DNA Full Genomic Sequence test brings your matches into times that are more recent. It means that you have a 50% chance of sharing a common maternal ancestor within the last 5 generations. That is about 125 years. (1)
Con: The full sequence MtDNA tests are expensive and the likeliness of matching is slim due to the fact that there are too few participants. 

Is mtDNA Testing Helpful?
Yes. Researchers may uncover the following:
  1. Haplogroup: Identify the origin/general region of my maternal ancestors (Native American, Jewish, etc.? What was their migratory path? 
  2. Indigenous: Identify an indigenous match. This is most helpful when matching ethnic groups. Are you Native American? Aborigines?
  3. Exact Match: With the assistance of your papertrail, descendants of maternal ancestors can be identified.
Summary:
The mtDNA contains the 3 regions mentioned: HVR1, HVR2 and Coding.

Referenced Articles
The information provided above was extracted from the following articles: 

Kathleen Brandt
a3Genealogy.com
a3Genealogy@gmail.com
Accurate, Accessible Answers

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