DNA Genealogy
by Relative Genetics
The next time you are watching your favorite CSI TV
show or a particular movie and stumble into the fascinating world of DNA,
you might be surprised to know that our DNA can do more than identify a
suspect or victim at a crime scene. In fact, DNA is now being used to
identify ancestors in the new and exciting field of DNA Genealogy.
DNA Genealogy takes
traditional genealogy and applies genetics to it. DNA Genealogy involves
the use of genealogical DNA testing to determine the level of genetic
relationship between two individuals (Genealogical 2005). DNA,
deoxyribonucleic acid, is used in the process because of its unique nature
and the fact that it is passed down from one generation to the next. In
the passing, some parts of the DNA remain almost completely unchanged,
while other parts change dramatically. This property allows for the
identification of certain consistencies between generations and provides
the ability to identify genetic relationships.
There are two types of DNA tests available for testing DNA Genealogy:
Mitochondrial DNA (mtDNA) and Y-chromosome DNA tests.
Mitochondrial DNA (mtDNA) is found in the cytoplasm of the cell instead of
in the nucleus as is Y-chromosome (Tracing 2003). mtDNA is passed by a
mother to both her male and female children without any additions or
mixing from the father. Therefore, your mtDNA is the same as your mother’s
mtDNA. mtDNA is different in nature compared to Y-DNA. It changes slowly
making it more difficult to determine close relationships and easier to
determine relatedness. If two people have the same mtDNA, there is a very
good chance that they also share a common maternal ancestor.
Unfortunately, it is difficult to determine if that common maternal
ancestor was recent or instead lived hundreds of years ago.
Y-chromosome tests have been used more and more recently to determine DNA
Genealogy. The Y-DNA tests are only available for males, because the
Y-chromosome is only passed down along the paternal line from father to
son. There are tiny chemical markers on the Y-chromosome that create a
unique pattern. This pattern of markers is what is called a haplotype. A
haplotype is used to determine one male lineage from another. This type of
testing is often used to determine if two individuals who have the same
surname share a common ancestor.
One of the early beginnings of DNA Genealogy was a study published by
Bryan Sykes in 2000 (Sykes and Irven 2000) that used DNA Genealogy
(Y-chromosome markers) along with surname studies to determine
relatedness. The study compared 48 men with the same surname of Sykes from
the regions of England and analyzed four Short Tandem Repeats (STRs) on
their Y-chromosome: DYS19, DYS390, DYS391, and DYS393. The study found
that of the 48 men tested, 21 had the same core haplotype and many others
were only one mutational step away from the core haplotype. Skypes
interpreted these results to reveal a common origin from an ancestor who
lived some 700 years ago (Butler 2005).
Since its early beginnings,
DNA Genealogy has come a long way and has grown rapidly. DNA Genealogy
continues to increase in popularity as the price of tests becomes much
more affordable and the number of markers and clarity of the tests become
greater. Additionally, DNA collection techniques make it a very simple and
pain-free process.
Sources
Butler J. (2005) Forensic DNA Typing; Biology, Technology, and Genetics of
STR Markers, 74, 231-232.
Genealogical DNA test. (2005, December 7). Wikipedia, The Free
Encyclopedia. Retrieved 21:52, December 8, 2005
Sykes, B. and Irven, C. (2000) American Journal of Human Genetics, 66,
1417-1419.
Tracing Your Ancestry Through DNA (2003) Genealogy.com.
About the Author
Relative Genetics, a leading provider of
DNA Genealogy, specializes in testing services on both the paternal
and maternal lines, extended and nuclear family relationships, and
Ancestral Origins TM analysis including both deep ancestry and ethnic
heritage analysis.
Relative Genetics may be contacted at
links@relativegenetics.com
Click here to view more of Relative's articles.
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