Mitochondrial DNA testing is a type of genealogical DNA test. A genealogical DNA testing is done to ascertain the genetic links amongst individuals. This process involves analysis of the structure of DNA of living persons. The results thus obtained, are compared with samples of deceased individuals. This test can bring out some very interesting facts regarding our haplogroup. As of now, mitochondrial testing does not have any medical value, as it is unable to specify the presence of any genetic disorders. The only intention to carry out this test is get information related to genetic genealogy.
What is Mitochondrial DNA?
DNA is a molecular substance present in our cells that has all the genetic instructions required to carry out the life processes or bodily activities. Mitochondrial DNA (mtDNA) is unique because it is found within the mitochondria of a cell. Most of the other DNA is present inside the nucleus of our body cells. Nuclear DNA is transmitted to the offspring from both parents. On the other hand, mtDNA is inherited only from the mother, and does not undergo any change by father's influence when it is transmitted from mother to the offspring. Thus, mtDNA can be used to know about the ascendants of the maternal side.
Mitochondrial DNA has three parts. One part is the coding region, and the other two are Hyper Variable Region1 (HVR1), and Hyper Variable Region2 (HVR2). mtDNA test determines the sequence of HVR1 only, or the sequence of both HVR1 and HVR2 of the test sample. The sequence found in a particular test sample is compared to the sequence of mtDNA of the reference sample available with the laboratory. This reference sample is called Cambridge Reference Sequence (CRS). The CRS is a source of information of human mitochondrial DNA (mtDNA), which is commonly found in Europeans. This however, is not a standard record of human mtDNA. The number of variations observed in the two sequences are enlisted in the test report.
These reports can reveal some astounding facts. It indicates the possible maternal haplogroup to which the person belongs. That is, it helps chalk out the complete family tree of one's maternal ancestry. Such a family tree can provide information about the family like its place of origin, where it migrated later, its ethnic background etc. In short, we come to know not only about our mother, and grandmother, but also about all those relatives who walked the Earth several hundreds of years ago. If the genetic differences shown in your report is similar to any other person's report that means the two of you may have a common female ancestor.
Mitochondrial DNA testing can prove or disprove any myth regarding our maternal ancestry. It provides information related to the native land of our maternal ancestors. It could help us reunite with some of our long-lost relatives. And, of course, it provides human genetic data that can help in research work related to genetic genealogy.
There are no major drawbacks of this form of DNA testing. MtDNA tests are unable to disclose anything about paternal lineage. The cost of the test is very high, and acts as deterrent for most people looking to take this test. Privacy issue is another matter of concern, because some laboratories keep the samples and the reports for their own use without any privacy agreement. Some people opine that the quality of testing is of low standard, and so the results obtained are not very accurate.
The technology of mitochondrial DNA testing is growing very rapidly. With the help of more research and development, interpretations of test results is bound to get better in the coming days. In the future, this could even help in the elimination of genetic diseases in individuals.