DNA Testing

Started with the National Geographic Genographic Project, now expanded by FamilyTreeDNA.com and many others, even offering free tests and access to database matches.
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DNA Testing

Postby bimjim » Thu Sep 25, 2008 8:54 pm

The Home DNA Test

Used in high-profile criminal investigations and paternity cases, deoxyribonucleic acid, commonly known as DNA, testing has now been popularized to prove relationships between individuals. The evolution of the test in past years has turned DNA testing into a popular tool for determining ancestry. The test also helps in determining if two people are related or descend from the same ancestor. Although DNA has been around for many years now, the cost has dropped enough to be affordable to average individuals interested in tracing their roots.

Using a home DNA test kit is very straightforward and requires so little expertise, that a child could carry out the procedure. In broad terms all that is required, is the removal of some cheek cells from the inside of the mouth by rubbing the cotton swabs on the inside of the mouth. A few gentle rubs of the serrated cotton swab on the inside of both cheeks should result in sufficient material being recovered to allow a full DNA paternity test to be carried out. It is important that a single DNA kit is used only for one person, to ensure there can be no possibility of a mix-up between samples. This will ensure the reliability of the final result.

The samples can be posted back via mail and within a span of one month an individual can receive a series of numbers that represent key chemical ""markers"" within his DNA. These numbers can then be compared to results from other individuals to help determine ancestry.

Samples are generally mailed back to the testing company to carry out a full DNA analysis, generally resulting in a report within a few weeks. The report should provide a clear unambiguous outcome to answer the question as to the biological relationship of the putative father to the child.

If the results of the DNA testing are to be used in a court of law, and require a legal standing, a home DNA test is not usually admissible. A much more rigorous approach in verifying the source of every sample is required. The process of obtaining the samples is witnessed and fully documented, including taking photographs of all the parties associated with each sample. This continuity is maintained with the laboratory environment, and allows an expert witness to provide an opinion in court, as to the relevance of the test results.
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Postby bimjim » Thu Sep 25, 2008 9:13 pm

It must be added to this explanation that the most common test is 12 markers, which is in itself insufficient for meaningful relationship indication - for genealogical purposes.

The 12 marker result was introduced to the general public by the National Geographic's Genographic Project, which is solely interested in the various tracks of humanity out of Africa thousands (or millions) of years ago. These tests were originally processed by the FamilyTreeDNA.com lab, and upgrades are easily performed by this company on the same stored samples of your DNA - so there is no need for another test, all you need is your original Genographic Project ID.

For showing a close relationship with another individual within the last 300 to 500 years, ideally a 25 marker or 37 marker result is preferred - and of course 67 markers is even more accurate.

One snippet that most proponents do not mention is that the markers are all taken from the same marker string - the 12, 25 and 37 result markers are all contained in the 67 marker test, and in the same sequence.

In other words, in the 67 marker test the first 12 markers IS the 12 marker result, the firsr 25 markers IS the 25 marker result, and so on.

Usually, for recent time (the last 400 years) a surname is used to provide additional verification to a match when performing a genealogical search.

There are a few databases on the internet where you can store your marker results. One of these databases is very pro-active and will try to match your results with every other DNA stored in its database, sending you periodic emails which alert you to potential matches. Most of these matches are linked to email addresses (where permitted by the other user). Another stores the results of all contributors and only performs search matches on request from the web browser.
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