APPLICATIONS OF DNA FORENSICS IN TODAYS WORLD

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APPLICATIONS OF DNA FORENSICS IN TODAYS WORLD
By Patricia Beauzile, Meghan moore, Donald Hahn,
Emily Hollens, Darwin Omar Larco

Applications of DNA Forensics As the field of DNA
forensics is ever increasing, the uses of DNA
forensics are also increasing, and the current
techniques are being refined.
Some of the most common and important uses of
DNA forensics are Diagnosis of/ Development of c
ures for Inherited Diseases diagnosis of cystic
fibrosis, hemophilia, Huntington's disease,
familial Alzheimer's, sickle cell anemia,
thalassemia, and many others education of prosp
ective parents as to the risks of having an
affected child identification of DNA patterns a
ssociated with diseases to help establish
treatment Biological Evidence paternity/matern
ity testing linkage of suspects to crime scenes
Identification of Individuals missing persons
and casualties ex. U.S. Armed Services Veter
inary Applications parentage testing of purebre
d animals wildlife studies identification of
inheritance patterns of genetic diseases
identification of genetic patterns in
populations investigate genetic susceptibility
of populations to diseases Agricultural Applicati
ons breeding of dairy animals cultivation of
various crops The ability of scientists to use D
NA fingerprinting to identify sequencing patterns
in many different organisms is creating new
possibilities every day, the extent of which is
still not fully known..
History Forensic science is a developing field t
hat owes its progression to the technical
advancements made in the lab. This field was
first coined as a science in 1936, but only
recently has the area been recognized as an
important asset in the fight against crime. This
is due in large part to DNA fingerprinting. DNA
fingerprinting was discovered accidentally by
Alec Jeffreys in 1984 and published in Nature in
1985. This discovery revolutionized the area of
molecular biology and became a gateway for many
key developments in forensics, which let to the
formation of DNA databases that store the DNA
information of suspected criminals or already
convicted criminals. The largest of such
databases, UKs National DNA Database, reported
in 2004 that it contained 2,400,000 individual
samples. In the United States there are similar
databases, such as the National DNA Indexing
System and Combined DNA Indexing System, which
work directly with law enforcement agencies to
match registered DNA samples to samples found at
crime scenes. DNA fingerprinting was first used
to provide evidence in a 1986 Pennsylvania case.
Samples were extracted from corpses involved in
the case, but much of the samples had been
degraded. A technique called the Polymerase Chain
Reaction (PCR) developed in the early 1980s
allowed for amplification of the limited samples,
which were then used as evidence in the case. In
this situation a limited supply of DNA would have
been difficult to generate enough significant
evidence since a technique developed in 1980
using restriction enzymes would have been the
alternative. This shows the importance of
developing techniques that enable scientists to
help in the courtroom environment. Furthermore,
refinement of these techniques allowed for the
Human Genome Project to initiate in late 1980s.
Currently, the entire human genome has been
sequenced, but there is still speculation as to
the number of genes actually present. To the
surprise of many scientists, current findings
show that there are 35,000 genes relative to
original predictions, but as progress is made a
much better understanding of the human genome can
be established. The benefits of using DNA evide
nce have been made apparent with the increasing
number of criminal cases that have been resolved
in light of DNA findings. A man in Pittsburgh, PA
was exonerated from a life sentence in May 2006
for a murder committed in 1989 as new DNA
evidence established his innocence. Advancements
in DNA matching have shown to be powerful tools
in both the scientific society as well as the
justice system. This particular area of forensics
has evolved immensely within the last 2 decades,
but there are still many issues that need to be
addressed such as ethical questions and
unexplained events in DNA science. There is no
doubt that DNA fingerprinting will be a prominent
area of research in the coming years.
Special Cases DNA forensic science has recently
been made popular because of its use in a number
of high profile cases. In 1991, scientists exh
umed the mass grave of the historical ruling
Romanov family. The last generation of the ruling
Romanov family, as well as their servants, were
captured, murdered, and buried in a mass grave in
Siberia in 1918. After the break up of the Soviet
Union, scientists used DNA forensic evidence to
identify the bodies in the mass grave. The
forensics team collected DNA from dental remains,
and skeletons. As a result, they discovered that
of the 11 people who were reportedly executed and
buried only nine were found in the grave.
In 1994, DNA forensic evidence was collected in
form of blood, skin, and semen samples taken from
the scene of the crime and was analyzed and
compared to O.J. Simpsons DNA taken from a cheek
swab sample. Although the blood sample and the
swab sample matched, this evidence was not used
in court due to it nature. In this case, forensic
evidence was considered circumstantial, and did
not prove absolute guilt. In the 1998 Swissair F
light 111 disaster, short tandem repeat (STR) DNA
was used to compare the DNA samples from the
disaster sight with the DNA samples from
searching family members. Scientists used the STR
method as well as a computer algorithm to find
similarity alignments between the victim DNA, and
the victims family DNA. With the use DNA
forensic tool, investigators were able track down
the missing passengers on the flight, and
identify lost loved ones. In 2001, after the att
acks on the World Trade Center, DNA forensics was
used to identify the missing victims of the
bombings. Forensics team combed through the
rubble to find any piece of remaining evidence to
link the dead to their family members. Dental,
blood, and hair samples were collected from
ground zero, and compared to the DNA samples
provided by family members in the form of hair
brushes, tooth brushes, and other items that may
have contained traces of biological tissue which
DNA could have been extracted out of.
References http//www.ornl.gov/sci/techresource
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www.accessexcellence.org/RC/AB/BA/DNA_Fingerprinti
ng_Basics.html http//en.wikipedia.org/wiki/DNA_t
esting www.news.ucdavis.edu/sources/ag_vet_DNA.la
sso http//www.wesleyan.edu/synthesis/GROUP4/FINA
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126943 http//www.ornl.gov/sci/techresources/Huma
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Stud. 2003 16(2) 2237. Clark, Michael. Forens
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and Ivan Balazs. 1993. "DNA-Based Identity
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Lynch, Michael. The Discursive Production
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1998) , pp. 829-868 Enhanced kinship analy
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FORENSIC/PAGES/JFS2003311.htm?Emystore
DNAi http//www.dnai.org/romanovs/index.html
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Ethical Issues One of the major problems with DN
A tests becoming common is the issue of privacy.
Once a persons DNA is sequenced, it is kept on
record. Most states do not require that the DNA
is destroyed after it is looked at, so the sample
may be available at later times for evidence.
Stored samples increase the possibility that
someone could get a hold another human being
genome. This is causing a stir because its
increasing the likelihood that government,
insurance companies, employers, schools, banks,
could possibly get their hands on the information
and use it in the future. These organizations
could possibly use the information for genetic
discrimination, not allowing people to obtain
loans, work, or get health insurance if they
found out that the person is predisposed to
certain illness, or cancer. One place in the wo
rld where privacy is becoming a major issue is
the UK. Police officials are allowed to obtain
DNA samples from all suspects in a crime without
permission. The UK has the largest DNA database
in the world. The use of this database involves
balancing between the rights of the individual
versus the right of the state. The UK is having
great success with finding criminals that match
crimes, but in doing so many believe their
tampering with an individuals rights.
Although DNA testing in the UK seems like a good
idea, practically speaking its not, due to the
fact that DNA sequencing takes a long time. There
is a large build up of samples right now in the
UK, so many cases have been dismissed, or trials
ended before DNA is sequenced. Other countries
such as Germany, Holland, France, Austria, have
also turned to DNA samples for answers but only
do testing when individuals are suspected of
committing serious crimes. Here in the USA,
police are unable to force suspects to give
samples due to the 4th amendment.
Measures must be taken to keep individuals right
of dignity and freedom. As stated in the
constitution, people should be given the choice,
so many argue that consent should be obtained
from each individual, before the DNA sample is
taken. People being tested need to be aware of
the consequences that will affect their lives,
along with the lives of family members. Another
point people are making is certain countries are
also not allowing people to move around while
being tested, and to object to DNA analysis of
their sample.
Problems Occurring in Analysis
The beauty of the growing field of forensic
science is the diversity in the methods of
analyzing DNA samples. Given this diversity, if
the nature of a sample does not allow it to be
analyzed with one method then it is probably
still useful to other techniques. The most
common problem with DNA samples is usually caused
by DNA degradation, which alters the structure of
DNA so that it cannot be analyzed with the
typical RFLP techniques. This can occur from
exposure to heat, humidity, sunlight, etc. as
well as contamination from bacteria and organic
molecules from the environment from which the
sample was withdrawn. Degradation causes longer
regions of DNA to be interrupted. As a result,
single tandem repeat assays work best for
degraded DNA because it involves the
amplification of a smaller amount of base pairs,
about 150 or less. Using these mini STRs and
amplifying them with 32 cycles of PCR has the
advantage of increasing the likelihood of more
DNA fragments of the desired alleles surviving.
This, in turn, increases the chances of
retrieving a complete DNA profile. Using longer
numbers of base pairs can lead to an imbalance of
the alleles during PCR amplification and even
dropout of an allele in the results which,
obviously, leads to invalid interpretations.
Longer sequences have been shown to have
significant dropout after two weeks of
degradation, as opposed to 8 weeks for the STRs.
Some alternatives to STRs have been in
development. One of these methods is the use of
single nucleotide polymorphisms, SNPs. These
methods have found to be useful because they,
based on the biochemistry mechanisms of extending
primers, can genotype numerous SNPs in a single
analysis. However, this requires a large amount
of DNA template and PCR product, whose values are
limited by sample amount. Another advantage of
SNPs is that they, being single base sites, have
much smaller amplicons, but the biallelic nature
of these makes it difficult to interpret results
from a mixed sample, thus requiring a
well-balanced assay. One final problem with this
method, because it is multiplex system, is that
it contains several transfers of the sample which
can lead to a higher chance of contamination.
Once past the step of using PCR to retrieve a
complete profile that has not been contaminated,
the next issue arises in the discovery of a
match. Forensics uses the probability of a match
and the frequency of alleles in a population to
determine the likelihood that the sample from the
scene came from a suspect. Degraded DNA almost
forces the use of mini STRs for forensic analysis
because of its accuracy, but the smaller amount
of base pairs and alleles used can mean that the
probabilities of a match are higher than those
for longer sequences. As a result PCR is used to
remove a suspect form the scene of a crime rather
than place him/her there. More problems exist wi
th current forensic DNA analysis techniques
outside of DNA degradation. One common problem,
specifically with RFLP methods, is that of band
shift on gels. Band shift is seen as DNA
fragments moving across the gel at different
speeds on the same gel. This can occur from
problems with DNA concentration, faulty gel
preparation, salt content in the sample, and
contamination. When it comes to determining a
match these band shifts could cause a problem
because it seems difficult to defend two pieces
of DNA as a match if the patterns are slightly
different. However, scientists have concluded
that this shift is just as likely to a match as
away from it. Many problems can arise from the
nature of the sample and the environment from
which is withdrawn. Standardization of the
techniques used to analyze the diversity of DNA
samples will lead not only to consistent results
but also consistent conclusions on the matching
of two separate DNA samples. If error in an
analysis occurs there is most likely no more of
the sample left to use for a second round of
analysis. Improving the methods used to analyze
the various types of DNA will steer away from
inconclusive results and lead to accurate
conclusions in identifying the source of a DNA
sample.