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For the Corson Cousins newsletter, January 2014
Corson Surname DNA Project
The project currently has 67 participants, 65 of whom have results. The most recent results arrived for Division IV.
Participant #6 tested positive for a single nucleotide polymorphism (SNP) named Z14. This result, along with the participantís lack of a "microallele" on DYS 458, places Division IV in a superfamily whose common ancestor was born approximately 44 generations (1320 years) ago (ca. 700 AD). Currently, 7 surnames have been identified in the superfamily, whose male-line ancestors cluster in the UK and the Netherlands. Details available in Cumberland Cluster A.
Advances in Genetic Genealogy
The beginning of the year is a good time to reflect on where genealogical DNA tests are heading. There are still three main types of tests:
As occurs for computers, the power (i.e., resolution) of DNA tests is increasing as their price decreases. While autosomal DNA tests are becoming more popular for finding relatives, most advances are being made in Y-DNA tests. At the beginning of surname DNA projects, tests focused on finding matches among 12-37 short-tandem repeat (STR) markers. The Y chromosome is known to contain more than 440 STR markers, and current standard tests examine 111 of them. Close matches among 111 markers indicate a close relationship within 10 generations, but the range of variability is high. Individuals who match may be as closely related as father and son, but they also may be distant cousins. For example, I have a perfect 111 STR-marker match with a 7th cousin, once removed.
The new frontier in Y-DNA tests is the matching of SNPs, which are mutations in single base pairs of DNA. Although SNPs occur less frequently than STR mutations, there are many more of them, which provides greater opportunity to identify markers specific to sub-branches of a family. Because SNPs occur less frequently than STR mutations, they also have the added advantage of being able to group lines with different surnames together. For example, Division IV Corsons are related to individuals with the surnames Chamberlain, Coen, Slaghekke, Atkinson, Pipkin, and Oliver, whose common male-line ancestor lived before the development of surnames.
The Y chromosome has about 20-25 million base pairs, of which 12-16 million can currently be mapped. Those who have had their Y chromosomes sequenced to date have each identified 25-40 "private" SNPs, which are SNPs that occurred too recently to be used for haplogroup assignment. In other words, these SNPs may have occurred only in specific family branches or in the testee himself.
In the near future (within 10 years), high-resolution SNP testing of several male-line branches of a family tree should be able to identify SNPs that occurred in specific male ancestors, thus allowing identification of descendants of particular male ancestors. The two most advanced tests are offered by Family Tree DNA ("Big Y" test) and Full Genomes Corporation, with prices currently ranging from $700-$1250. These prices are far too high for testing several members of the same Division, but they are falling.
More information about genetic genealogy and the kinds of DNA tests available can be found on the website of the International Society of Genetic Genealogy (ISOGG).