Thursday, October 23, 2008

Paternal Line Research

Author: Curt Whitesides

Have you ever looked into the mirror and wondered, ""Where did I get that hair?"" yet at the same time realized that the older you get the more you look like your mother or father? The DNA that a son receives from father is not only influential in determining eye color, hair style, and height; but also in identifying who the father was. More specifically Paternal Line Research is defining who we are by helping to determine where we came from.

Paternal Line Research uses

Y chromosome testing to trace the paternal line. Throughout time, Y-chromosome tests are only available for males, because the Y-chromosome passed only down the paternal line from father to son. There are tiny chemical markers on the Y-chromosome that create a unique pattern. This pattern is used to distinguish male lineages from each other. This type of testing is often used to determine if two individuals who have the same surname share a common ancestor. Furthermore, this test is often used to provide additional also details in paternity cases where the alleged father is not present for testing.

The Y-chromosome is passed from father to son and has the property of remaining unchanged for several generations. Y-chromosome mutations generally occur once every 500 generations. Because of this consistency in the Y-DNA, it is very accurate in assessing relatedness and even more accurate in assessing un-relatedness (Paternal 2005). Additional information that can be gathered from Paternal Line Research is the approximation of a common ancestor or most recent common ancestor (MRCA) and the most likely estimate (MLE) to a common ancestor--an estimate of when the most recent common ancestor between two relatives lived (presented in generations).

The field of Paternal Line Research has rapidly improved in recent years due to the fact that Y-chromosome analysis has improved. New markers have been discovered and population groups are being characterized (Kayser et al. 2004). Various tests have been conducted as well as validation studies. Both have demonstrated that

Y chromosome testing is in fact reliable (Butler 2005). Many different examples abound that indicate the value that Paternal Line Research testing has in forensic DNA casework. In addition, internet-accessible databases house thousands of Y-DNA haplotypes making Paternal Line Research an increasingly popular and accessible field.

The Easy Y-Match and Exact Y-Match search engines of the Relative Genetics' database allows searches of Y-chromosome paternal line test results. These two search functions will allow clients to identify other individuals with whom they may have a close genealogical connection. Web site visitors may also search for possible relatives using a basic surname search. The recently improved flexibility of the Web site allows individuals to create new projects, participate as members in multiple projects, and accept project members who have been tested by organizations other than Relative Genetics. In addition, members of Group Projects will find that the color coding and sorting features of the group data table makes it easy to quickly identify relatives within their group. Web site visitors are also granted convenient, effective access to the Sorenson Molecular Genealogy Foundation database.

Paternal Line Research is still largely untapped and it will be very interesting to see what the future holds. For example, DNA casework currently has yet to accept

Y chromosome testing as a valid standard and instead still sees it as a specialized technique only to be used in unique situations (Butler 2005). Databases will need to expand in size and power in order to strengthen the statistical information regarding a match. In addition, the many different markers that are available need to be further characterized to better define where they fit in analyzing haplotypes and the strength of matches. At any rate, Paternal Line Research has great potential in addition to the great success that it has already produced.

Sources

Butler J. (2005) Forensic DNA Typing; Biology, Technology, and Genetics of STR Markers, 74, 231-232.

Kayser, M., Kittler, R., Erler, A., Hedman, M., Lee, A.C., Mohyuddin, A., Mehdi, S.Q., Rosser, Z., Stoneking, M., Jobling, M.A., Sajantila, A. and Tyler-Smith, C. (2004) American Journal of Human Genetics, 74, 1183-1197.

Paternal Lineage. (2005). DNA Diagnostics Center. http://www.dnacenter.com/dna-testing/paternal-lineage.html.

About the author: Relative Genetics is a genealogical company specializing in DNA testing.

Click here to learn more about

Y chromosome testing of the paternal line.

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