DNA testing is impacting various
segments of our society, from forensics to family relationships to genealogy.
There isn't a single DNA test that is appropriate in all of these different
circumstances. Depending on the answers sought and the samples available, there
are actually different types of DNA tests that compare different types of DNA
samples, and provide different types of DNA profiles.
DNA profiles, or DNA fingerprints, are obtained through the analysis of DNA
samples, usually collected from individuals by swabbing the inside of their
cheek. Each cell in our body contains DNA, and the DNA molecule for each of us
is unique. So the use of DNA profiles to conclusively identify individuals has
brought certainty to many questions that remained unanswered for previous
generations.
The most commonly used
DNA testing method today is called "short tandem repeats," or STR. Most
parts of human DNA are identical, but there are individual differences
isolated in small segments of the DNA chain. These differences usually
occur at the same location on the chain. STR testing looks for these
differences at specific DNA sites where they typically occur. STR is an
extremely accurate DNA testing method, with the chance of
misidentification being one in several billion. STR testing is usually
used in forensics and for DNA paternity testing.
Another testing method compares differences in the Y chromosome.
Contained in the DNA's nucleus, the Y chromosome is passed from father
to son. In each paternal line, the Y chromosome is made distinctive by
tiny chemical markers. These Y chromosome fingerprints allow individuals
to be matched to particular patrilineal lines. Y chromosome testing is
often used in ancestry studies, surname comparisons and human migration
research.
Mitochondrial DNA (mtDNA), the maternal counterpart to the Y chromosome,
is passed from mother to offspring (both male and female). Mitochondrial
DNA is located in the cytoplasm of the cell and changes very little from
generation to generation. This makes mtDNA analysis a highly effective
tool for maternal lineage for hundreds of generations. MtDNA is most
often used in human ancestry and origins research. It has limited uses
in forensics, because mtDNA is easily contaminated.
Another interesting development in the world of DNA testing is the
creating of DNA banking services. Companies providing this service
guarantee the secure storage of DNA samples for future testing. This
facility may be important for those who are concerned about illegitimate
claims against their estate. DNA banking is also used by individuals in
high-risk profession who may wish to store a DNA sample if the need for
positive identification is required. If a loved one is kidnapped or goes
missing, banked DNA may be helpful.
As biotechnology continues to progress, it's likely that even more
different types of DNA testing and applications will emerge.
