Sunday, April 24, 2011

MITOCHONDRIAL DNA ----A MATTER TO UNDERSTAND

http://www.dnareunion.org/article.php?type=mt&__atoken=__NONE__
Mitochondrial DNA (mtDNA) is found in the cytoplasm of most of the cells in our body. All individuals, both males and females, carry mtDNA.
mtDNA has an unique inheritance pattern which differs from all the other types of DNA in our body. It is passed down strictly along the maternal line from mother to child. While males carry their mother's mtDNA, their children will inherit their mtDNA from their own mother, not their father. Thus, only daughters will pass the mtDNA on to future generations.
The maternal inheritance pattern of the mtDNA has important significance for tracing maternal lineage. While most other types of DNA in our body are mixed as they are passed down from generation to generation, the mtDNA remains unmixed because it has a strict line of descent from mother to child. This means that our mtDNA is shared by all individuals who descended from the same maternal lineage and share the same maternal forebearers. By testing our own mtDNA, we are able to indirectly read the mtDNA genetic code of our own maternal ancestors from thousands of generations ago. An individual's mtDNA can be compared with others to look for potential relatives who have descendend from the same maternal lineage.
mtDNA Testing
The mtDNA is a circular loop of DNA (plasmid) 16,569 base pairs in length. The mtDNA loop consists of 3 main regions: HVR-1, HVR-2 and Coding region. mtDNA testing involves the testing of DNA in one of these three regions to look for SNP mutations. SNP stands for "single nucleotide polymorphism" and are single changes in the mtDNA which are passed down to further generations. The base mtDNA test is the HVR-1 test. The HVR-1 region contains an abundance of SNP markers and is useful for maternal lineage searches. The HVR-2 region contains additonal markers which will increase the resolution of the search. The Coding region also contains SNP markers which will proivide even further enhancement of resolution once a match is found.
mtDNA markers will allow you to search for individuals who share the same maternal lineage as you and rules out individuals who do not share your maternal lineage.
Lineage traced: Maternal line (mother's mother's mother's line)
Strengths: Can trace both males and females who descended from the same maternal line.
Limitations: Can only trace relatives who descended from the same maternal line (mother's mother's mother's...line). Cannot trace other lines, such as descendents from the mother's father's line, or the father's mother's line. Will not tell you your relationship type.
Who can be tested? Both men and women have mtDNA so both can participate.
How It Works:
1. Get your mtDNA marker certificate. If you have not tested yet, order your test at Genetrack.
2. Enter your mtDNA data into DNA Reunion (/).
3. Create your search list.
4. You will be instantly notified when a potential match joins the registry.
As the database grows, you will find new matches. You can search at any time and as many times as you wish.

What is tested?

HVR-1 RegionAll markers between locations 16001 to 16520. The HVR-1 Test is the most informative mtDNA test, and it is always the first test that is performed when you start tracing your maternal ancestry (the Maternal mtDNA test). The HVR-1 test uses "DNA sequencing" technology to read all of the nucleotides from locations 16001 to 16520 of your mtDNA. This is the entire HVR-1 region, located in the D-Loop of the mtDNA.
HVR-2 RegionAll markers between locations 1 to 400. Like HVR-1 testing, the HVR-2 test also uses "DNA sequencing" technology. This test focuses on reading all of the nucleotides from locations 1 to 400 of the mtDNA. This is the entire HVR-2 region, the second most important region in the D-loop of the mtDNA.
Coding Backbone SNPsSelected SNP markers in the Coding region of the mtDNA. While the markers in the HVR-1 and HVR-2 Regions can be easily detected by sequencing technology, the Coding Region is extremely large, making sequencing impractical. The mtDNA SNP Haplogroup Backbone Test is a special panel of approximately 20 markers in the Coding Region which are specific for haplogroup determination. By testing just the HVR-1 or HVR-2, you will only receive part of the "picture" of your mtDNA. The SNP Haplogroup Backbone Test will allow you to view markers in the Coding Region of your mtDNA.
Coding RegionAll markers in the entire mtDNA from 1 to 16520, including the entire HVR-1, HVR-2 and Coding regions.

DNA Reunion is a free international DNA registry for people from around the world to find family members and family connections using DNA.
If you have not tested yet, order your test at Genetrack.

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