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Background of DNA use in Genealogy

Page history last edited by PBworks 13 years, 9 months ago

1.1 DNA testing can be performed to match other specific people and to identify general backgrounds. Paternal lines are tested by Y-DNA and maternal lines by mtDNA.

 

In Y-DNA between 10 and 67 markers are tested. A Y-DNA haplotype is derived from the markers. Haplogroups are large groups of haplotypes defining a genetic population.

 

As summarized by Ann Turner in the DNA Genforum -

"By convention, we reserve the word haploTYPE for results of STR testing. Markers such as DYS390 and GATA-H4 are STRs (Short Tandem Repeats), and the results can vary somewhat within a lineage due to the relatively high mutation rate of STRs.

 

SNP testing is used to formally confirm a haploGROUP, such as R1b3. SNPs (Single Nucleotide Polymorphisms) have such a low mutation rate that they are very stable -- they may even have occurred only once in all of human history. Everyone in the same haplogroup descends from one common ancestor, who lived thousands of years ago and was the first person to have that mutation.

 

The founder of a haplogroup had a specific haplotype, and his descendants often preserve traces of that haplotype. That means the haplotype can sometimes be used to predict the haplogroup."

 

Markers within a haplotype have been found to have varying mutation rates.

 

http://www.ysearch.org/ has a database of 20,000 plus Unique Haplotypes from 28,000 plus records.

The choice on how many markers to test is discussed at

http://www.ftdna.com/faq2.html

It depends on the goals of closeness of matching a common ancestor.

 

mtDNA tests are based on HVR1 and HVR2 results.

http://www.mitosearch.org/ has a database of mtDNA results.

 

More DNA testing information can be found at

About.com DNA Overview with list of related articles

Also see http://en.wikipedia.org/wiki/Genealogical_DNA_test

 

There is a collection of Genealogy using DNA bookmarks at at http://del.icio.us/gendna . It is open for anyone to add or edit.

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