Wednesday, June 30, 2010

So You're Ready to Test Your DNA?

(Click here for Step 1 of this series, Which DNA testing company?: http://genealogyanddna.blogspot.com/2010/01/so-youre-ready-to-test-your-dna.html)


Step 2: Which Test to Choose?

A Y-DNA test can only be taken by men (women do not have a Y-chromosome). It tests the straight paternal line -- father to his father to his father, etc. An mtDNA test can be taken by either men or women. It tests their straight maternal line -- mother to her mother to her mother, etc.

How Many Y-DNA Markers?

A Y-DNA test serves two purposes: genealogical and anthropological. The genealogical results are reflected in your haplotype; your haplogroup is anthropological and gives you insight into the path your ancestors took out of Africa many thousands of years ago.

The basic, entry level Y-DNA test is 12 markers. This tells you what your haplogroup is and places you, in a general way, on the tree of mankind. It can also determine that you do not match another man. It cannot tell you that you do match someone else.

The 37-marker Y-DNA test is extremely useful and can be the only test you need to determine whether or not you match another individual or group of men who share a common ancestor.

The definitive test is 67 markers. This is likely to resolve lingering doubts about near matches, for example.

As to learning more about your haplogroup, the Deep Clade test can refine your placement on the Tree of Mankind to enable you to better understand the path your ancestors took out of Africa and sometimes where they settled. There are additional tests that can further refine your anthropological understanding.

Which mtDNA Test?

HVR1 is the basic test that provides the equivalent of a Y-DNA test of 12 markers but only in terms of anthropological time. Any match at this level is virtually meaningless because the time to a common ancestor can be thousands of years ago. The HVR2 test brings this down to, perhaps, a thousand years, which is still not useful for genealogy in most cases. The mega test, or FGS for Full Genetic Sequence, applies only to the mitochondria, but it is the ultimate test for those who wish to find meaningful matches in their maternal line.

What About Autosomal Tests?

This very new type of test can be either health-related or genealogical. 23andMe offers a test that includes both, or you can choose just health-related. Family Tree DNA, which specializes in genealogical testing, offers the Family Finder test that enables us to find distant relatives, including 5th cousins, aunts and uncles, for example. This test is not restricted to males or females; both can participate.

Note that neither of these autosomal tests is a substitute for the Y-DNA or the Full Genetic Sequence mtDNA test.

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