Genetic genealogist CeCe Moore provided an excellent tutorial on genetic genealogy with graphic examples in her presentation "Getting Started in Genetic Genealogy" to 28 members and guests of the Chula Vista Genealogical Society on Sunday, 7 October at Bonita-Sunnyside Library in Bonita.
In a relatively short 15 years, genetic genealogy has grown from the first Y-chromosome tests on Jewish priests to full genome tests for selected people. CeCe described the four genetic genealogy tests available for a fee at several genetic testing companies:
* mtDNA - mitochondrial DNA tests provide genetic information passed by a biological mother to her male and female children.
* Y-DNA - Y-chromosome DNA tests provide genetic information passed by a biological father to his sons.
* atDNA - autosomal DNA tests provide genetic information on 22 chromosomes passed to a person by his/her biological parents (contributed by all biological ancestors)
* X-DNA - specific X-chromosome tests are not available yet (passed by a biological mother to a child)
CeCe described the science of DNA - a mother's egg provides about half of a child's DNA, as does a father's sperm. Each human person has 46 chromosomes - 23 from each parent, including 2 sex chromosomes, which define the genetic characteristics of a person. The chromosomes are in the nucleus of each cell. The mitochondrial DNA is in the cytoplasm of each cell. The sex of a child is determined by the X or Y chromosome contributed by the father - an X chromosome creates a female child, and a Y-chromosome creates a male child.
The mtDNA test results can be used to define the matrilineal line (mother to child) for a person - a person with the same mtDNA results probably has a common female ancestor back in time. The Y-DNA test results can be used to define the patrilineal line (father to son, the surname line) for a male person - a person with the same Y-DNA results probably has a common male ancestor back in time.
Maternal or paternal Haplogroups contain similar characteristics for mtDNA and Y-DNA, respectively, and the results are classified by a letter and subgroups. These haplogroups can be used to identify human migration over the past 100,000 years.
Surname projects are available for Y-DNA testers that can help prove patrilineal lines by descent if there are nearly identical matches with other males with the same Y-DNA markers. If there are fewer matches of males with a common patrilineal ancestor, then either there is an adoption, a "non paternal event," or a person's genealogical research is wrong.
Autosomal DNA tests can be used to determine which genetic material was contributed by a specific ancestor by comparison of a person's test results with a relative's test results. However, autosomal tests can only indicate relationships as early as approximately 5th cousins.
CeCe described the autosomal tests provided by 23andMe (called Relative Finder), Family Tree DNA (called Family Finder) and AncestryDNA. These tests, with more than half a million markers, compare a person's results with those of reference populations, and results in a definition of "Deep Ancestry" (for example, 50% Europoean, 25% African, and 25% Asian) for the person tested.
Automsomal tests can also provide indications of relationships with other persons. CeCe provided comparisons of her test results with a number of close relatives. By testing several relatives, and knowing the genealogical relationships, the specific segments of DNA on specific chromosomes can be attributed to a specific ancestor.
There were many questions about the DNA tests, their costs, their results, and about genetic characteristics and medical problems. Only 23andMe tests for, and provides information for, medical problems. CeCe had an answer for everyone.
CeCe wrote four articles on the Geni.com blog about Getting Started in DNA Testing - see:
* Part 1 - http://www.geni.com/blog/dna-testing-for-genealogy-getting-started-part-one-375984.html
* Part 2 - http://www.geni.com/blog/dna-testing-for-genealogy-getting-started-part-two-376163.html
* Part 3 - http://www.geni.com/blog/dna-testing-for-genealogy-getting-started-part-three-376261.html
* Part 4 - http://www.geni.com/blog/dna-testing-for-genealogy-getting-started-part-four-376433.html
You can read CeCe Moore's blog - Your Genetic Genealogist - at www.YourGeneticGenealogist.com.
You can join (free) the International Society of Genetic Genealogy at www.isogg.org, and receive an invitation to join the DNA Newbie mailing list, which CeCe moderates.
This workshop was a two-plus hour session that passed a lot of information about DNA testing, and was well received by the attendees.
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