DNA Fingerprinting

DNA FINGERPRINTING The discovery of DNA fingerprinting revolutionised criminal identification and forensic science. Just like ink fingerprints, DNA fingerprints are unique to every individual and can be used as legal evidence in court to prosecute or defend alleged criminals. In paternity cases, DNA fingerprinting technology can be used to identify or rule out persons as biological parents of a child. However, the development of this technology has given rise to a number of ethical debates including whether a person can be forced to give a DNA sample for analysis and who should gain access to such personal information. Also, the concept of a DNA database raises questions about personal privacy and civil rights, although it could be a key contributor to genetic research. Scientists are consistently finding new ways in which the applications of DNA can be expanded.

 Figure 1 – The

structure of DNA (Genelex, 2006)

The structure of DNA (deoxyribose nucleic acid) was first discovered by Dr James Watson and Francis Crick in 1953. Its double helix structure is made up of phosphate, sugar (deoxyribose) and pairs of bases – adenine always with thymine, and cytosine always with guanine (as shown in figure 1). The double helix is wound around itself many thousands of times to form chromosomes. Each of the 23 pairs of chromosomes is made up of different sections of DNA called genes and each one of these genes is responsible for a particular feature or process in the body. For example, there is a specific gene for blue eyes, and another for green eyes. Most of the human genome is the same for everybody – every individual has a liver, a heart, and produces certain proteins that catalyse chemical reactions in the body. Only 0.1% of human DNA is unique to each individual, as discovered by Professor Sir Alec Jeffreys.

In order to isolate this section of DNA, an enzyme is used to scan along the DNA to look for a particular pattern in the bases (Eg. AAT). The enzyme cuts the DNA every time this pattern occurs so that the DNA ends up in many tiny pieces. Because this section of DNA is highly variable between individuals, the length of the pieces of DNA cut by the enzyme will be different for every person. The DNA fragments are then inserted into wells in a tray of hard polymer gel (apparatus as shown in figure 2) and an electric current is passed through the gel so that the different sized pieces of DNA separate, depending on their length, to form a DNA fingerprint (as shown in figure 3). This process is called electrophoresis and is used in forensics laboratories for comparing DNA samples. The development of DNA fingerprinting allowed for faster and more accurate identification of suspects in criminal investigations. For example, blood found at the scene of a crime contains white blood cells that contain DNA (red blood cells don‟t have a nucleus and consequently don‟t contain any DNA). Forensic scientists can then take a sample of the blood, isolate the unique section of DNA and perform electrolysis to make a DNA fingerprint. All tried and convicted criminals have their DNA fingerprints in a database so they can be easily identified if they re-offend. However, there

© Sarah Don, Australia, 2008

 Figure

2 – Electrophoresis

apparatus (Ussery, 2000)  Figure 3 – DNA

fingerprints (Peri, 2008)

may be more than one set of DNA at a crime scene. For example, the victim may have bled, the criminal may have left hair behind and there could be traces of people‟s DNA left from days, months or years before the crime from sneezes or sweat. Apart from the samples taken from the scene, forensic scientists have to take samples directly from the victim, any suspects, and anyone who frequented the crime scene before the crime occurred in order to rule out the innocent people. Also, any police officers, detectives or forensic scientists who enter the scene of the crime have to take special precautions so that they do not contaminate the area with their DNA. Unfortunately for the victims, defence attorneys can use the argument of contaminated DNA samples in court. A particularly famous case in which the use of DNA fingerprint evidence was questioned by the court was that of O.J. Simpson, 1994-1995, who allegedly murdered his ex-wife her friend. Simpson‟s defence attorneys argued that the way in which the DNA sampl es were collected did not meet forensic standards, hence jeopardising the DNA evidence. (Finkel, 1995) Because of the discrepancies over the collection methods of the DNA evidence presented in his case, Simpson was not charged with murder. When DNA fingerprinting was first introduced as evidence in court it was regarded as infallible, however the DNA sample collection method has to be closely monitored to make sure it is not contaminated, in order for it to be used as reliable evidence in court. Although the 0.1% of DNA sampled to make a DNA fingerprint is highly variable between individuals, there is still a 1/100,000 chance that two unrelated DNA fingerprints could match. However in the context of a crime scene there is almost no chance of finding two people locally with identical DNA fingerprints. (Finkel, 1995) Identical twins also challenge the reliability of DNA evidence in court. Identical twins are monozygotic – developed from the same zygote – so they share the same DNA. If twins were involved in a criminal investigation all DNA evidence concerning them would be void because there would be no way of telling the difference between a DNA fingerprint from either of the t wins. DNA fingerprinting can also be used to resolve paternity disputes. DNA samples are taken from the mother, child, and alleged fathers, and electrophoresis is used to create DNA fingerprints of all the samples. When the DNA fingerprints are compared, all the nodes in the child‟s DNA fingerprint must match up with nodes from either the mother or the father. The child cannot have a single node that has not come from either the mother or father. Using this method, potential fathers can be eliminated. In Figure 4, father number two (F2) can instantly be eliminated because he does not provide the second node that the child posses. The child did not get this node from the mother (M) so it has to have come from the father, and as father number two does not possess it, he could not possibly be the father of the child. Father number one (F1) can also be eliminated because the child‟s second -last node did not come from the mother, and father number one does not possess it either. This leaves father number three (F3) as the only remaining potential father of the child. As the child does not inherit all the nodes from both mother and father (only a combination) it is not possible to identify a father with 100% certainty. Only eliminations can be made.

M

Child

 Figure 4 – Example

F1

F2

comparison

of the child’s

DNA fingerprint to that of the mother and alleged fathers in a paternity case


F3

In Australia only convicted criminals are required to supply a DNA sample for the national database. Forensic investigators cannot force suspects to give a DNA sample for analysis. However, if there is enough other evidence to suggest that they are guilty of the crime they are suspected of committing, a court order can be obtained to force the suspect to provide a DNA sample. If a person is suspected of committing a crime and they provide DNA sample, but are then proven innocent, their DNA fingerprint is destroyed and not added to the national database. However, in the situation of a national disaster, having access to a national register of DNA fingerprints – not just of criminals, but of every person in Australia – would be extremely helpful in the identification of victims as well as missing persons. One country that has very successfully implemented a national DNA database is Britain. Since its launch in 2004, the United Kingdom‟s national DNA database has collected over 113,000 DNA samples from people who have been arrested but not charged. Currently, the database has 5.2% of the British population‟s DNA on record. However, the inventor of DNA fingerprinting, Professor Sir Alec Jeffreys has concerns about the retention of innocent people‟s DNA, saying that the database raises significant ethical and social issues. A senior appeal court judge, Lord Justice Sedley, has also expressed his concern, commenting that the database unfortunately places the innocent on par with the guilty. (ScienceDaily, 2008) Many people worry about the security of their DNA profiles, fearing that if they were to fall into the wrong hands, their DNA profile could be sold or used to steal their identity. However, the U.K. has very strict legislation that restricts who can gain access to the DNA profiles, how they are handled, and what the information is used for, in order to make sure that the database holds true to the privacy expectations of the public. Having a national DNA database can also contribute to scientific research. The computers that store the DNA profiles can search for patterns – certain traits corresponding with other certain traits – which helps researchers to find meaningful genetic associations for particular diseases. Once all the genes in the human genome have been associated with corresponding features, traits or diseases, scientists will be able to detect the presence of certain genes from a person‟s DNA fingerprint or original DNA sample. This presents a plethora of ethical issues, however . A person‟s knowledge of their genetic predispositions for particular diseases could affect their state of mind and attitude towards life. For example, if a person has their DNA analysed and finds out that they have a gene associated with heart disease they may modify their lifestyle out of fear and choose not to participate in activities that they would ordinarily enjoy. This could lead to a whole range of other more mentally-inclined illnesses. Also, if insurance companies could access their clients‟ DNA profiles and could see that they had an increased risk of developing breast cancer, for example, the insurance company may choose not to insure them for potential medical expenses. Willingness Willingness of parents to have their child undergo genetic testing for certain diseases Not Willing 8% Willing if there is treatment available 39% Willing even if there is no treatment available 53%  Figure

The advantages of genetic testing are also recognised by the public, however. In a poll conducted in the U.S. in 2007, parents were asked if they were willing for their child to undergo genetic testing to determine if they were at risk of developing certain diseases (the results are shown in figure 5). Lead researcher, M.D. Beth Tarini said that “some parents feel that even without a treatment, genetic testing would better prepare them to deal with their child‟s illness.” Over 4million newborns in the U.S. each year undergo

5 – U.S. polls regarding genetic testing of children

(ScienceDaily, (ScienceDaily, 2007)


genetic testing for diseases such as cystic fibrosis, phenylketonuria (a metabolic disorder caused by a deficiency in the enzyme enzyme phenylalanine hydroxylase) hydroxylase) and sickle sickle cell anaemia. Comparing all the DNA samples from these genetic tests by collecting them in a DNA biobank could assist researchers in identifying associated genes. Already, the DNA biobank in the U.K. has assisted in the identification of new genes related to diabetes and Crohn‟s disease. (ScienceDaily, 2007) In the future, more and more genes will be identifiable through different tests and thus provide individuals with more information about their genetic make-up, if they choose to know. DNA fingerprinting has contributed heavily to the development of several industries concerning health and forensics. As DNA is unique to every individual, people sometimes worry about what could happen to their genetic information if it were to fall in the wrong hands. Laws and regulations have to be made in order to control the lawful and constructive use of such technologies, and individuals have to decide how willing they t hey are to supply their DNA information i nformation for national registers and testing. As the range of uses for DNA fingerprinting broadens, more ethical issues will arise that authorities will have to address. However, over the past two decades at least, DNA fingerprinting has enabled more genes to be identified and more criminals to be convicted than ever before, making it one of the most revolutionary discoveries of science yet.


BIOGRAPHY The Age Education Unit , (2002) DNA testing of criminals, The Age Newspaper http://www.education.theage.com.au/pagedetail.asp?intpageid=128&st http://www.education.theage.com .au/pagedetail.asp?intpageid=128&strsection=students&intsec rsection=students&intsectionid=0 tionid=0 (10/05/2008) This Age Newspaper article was compiled by The Age Education Unit to highlight the use of DNA fingerprinting in criminal investigations and forensic science. Also in this article, Liberty Victoria, one of Australia‟s leading human rights and civil liberties organisations. raised a few concerns about the possible misuse or abuse of this technique an d highlighted the need for more debate on these issues. Arnold, B (2006) Caslon Analytics Biometrics, http://www.caslon.com.au/biometricsnote11.htm (19/05/08) Caslon Analytics is an Australian research, analysis and strategies consultancy that has a particular interest in technology and the regulation of its use. This source lists information about polls and surveys conducted in the U.S. regarding people‟s a wareness and acceptance of certain for ensic for ensic identification techniques. The Associated Press (1996) DNA evidence was contaminated through bad collection, defense asserts - Dec. 13, 1996 , http://www.usatoday.com/news/index/nns053.htm (05/05/2008) This is a news report on the trial of O J Si mpson looking at some of the mistakes police technicians made during haphazardly collecting blood samples, thus contaminating the DNA evidence and making it unsuitable for use by the prosecution. Australian Government, Department of Innovation, Industry Science and Research, (1998) 1998 Australia Prize - Professor Sir Alec Jeffreys (UK) , https://sciencegrants.dest.gov.au/scienceprize/Pages/Doc https://sciencegrants.dest.g ov.au/scienceprize/Pages/Doc.aspx?name=previous_winn .aspx?name=previous_winners/Aust1998Jeffreys.htm ers/Aust1998Jeffreys.htm (02/05/2008) This Australian Government web article describes how the 1998 Australia Prize co winner Professor Sir Alec Jeffreys discovered DNA fingerprinting, one of the most effective tools in modern crime detection. Bunworth, M. (2005) Missing persons database to be set up Australian Broadcasting Corporation, 7:30 Report Broadcast: 09/02/2005, http://www.abc.net.au/7.30/content/2005/s1299506.htm (05/05/2008) This is a transcript from a current affairs program that tha t looks at the Federal Government‟s plans to trial a national missing persons database using the CrimTrac agency, which provides DNA, fingerprints and other evidentiary support to all o f Australia's police forces. Concerns have been raised by mental health professionals about the need to ensure that people with mental health problems who go missing, don‟t end up on the criminal database. Fairfield, E. (1999) What is 'gel electrophoresis,' and why is it so important for DNA testing in criminal cases? http://www.sciam.com/article.cfm?id=what-is-gel-electrophores (01/05/08) This is an article published in Scientific American, a highly regarded scientific journal. Eric Fairfield, a researcher, talks about his research into a new form of electrophoresis. This form of electrophoresis is not „new‟ in 2008, however it gives a good explanation by the researcher himself about how it works. This is the form of electrophoresis most commonly used today. Finkel, E. (1995) The O.J. Simpson case; DNA fingerprinting on trial http://www.wehi.edu.au/resources/vce_biol_science/articles/finkel2.html (12/05/08) This is a radio interview with Elizabeth Finkel on ABC‟s Ockham's Razor about DNA fingerprinting and the O.J. Simpson case. It‟s a web resource for DNA science workshop for Victorian Certificate of Education (VCE) biology teachers. Within the discussion issues concerning the frequency of a particular DNA fingerprint are explored, as well as the standard methods for collecting DNA information from a crime scene without jeopardising the useable evidence in court.


Genelex Corporation (2006) DNA Molecule, http://www.genelex.com/paternitytesting/paternityslide1.html (05/05/08) Genelex Corporation is an internationally recognized leader in paternity testing and forensic DNA analysis. They have played a key role in the invention and development of technologies in use by identity and paternity testing laboratories throughout the world. This is a credible source because they are a health-related organisation that is monitored by the American Government. They provide simple diagrams pertaining to DNA and genetics that were useful to assist in explanations in this essay. Haywood, B. (2004) Sampling the evidence The Age Newspaper http://www.education.theage.com.au/pagedetail.asp?intpageid=1284&s http://www.education.theage.com .au/pagedetail.asp?intpageid=1284&strsection=students&intsec trsection=students&intsectionid=0 tionid=0 (05/05/2008) This article expresses concerns about proposed changes to Victorian laws for collection of DNA samples. Police may be given the power to take non-intimate (hair, fingernail) DNA samples without a court order. Some argue that removing the need for a court order in some cases leaves the process of DNA profiling with insufficient safeguards to prevent corruption or misuse of the system, and will undermine the presumption of innocence, placing the onus on the accused to prove their innocence rather than the prosecution to prove guilt. The article intends to scare the reader by exaggerating the proposed increase in power of police. Kirby, M. (The Hon Justice) Justice) (2000) DNA Evidence: Proceed With Care Speech at Science Seminar http://www.hcourt.gov.au/speeches/kirbyj/kirbyj_dna.htm (04/05/2008) This is a transcript of a speech given by The Hon Justice Michael Kirby at a seminar on science and digital/cyber crime at the University of Technology, Sydney, 16 March 2000. While DNA technology is a great advancement in fighting crime, Justice Kirby is reminding the audience that the basic civil right of people should not be eroded in the pursuit of criminals. This is a credible source as Justice Kirby is a well respected judge in the High Court of Australia. Magill, M. (2008) Crimtrac’s national DNA database expands to fight crime , Australian Government CrimTrac Agency Media Release, http://www.crimtrac.gov.au/systems___projects_key_dates_in_the_history_of_forensic_dna_profiling.html (12/05/2008) This Australian Government web site has a timeline in the history of forensic DNA profiling. It also looks at the use of the national DNA database by police and law enforcement agencies to connect offenders with unsolved crimes. This is a credible source of information showing the application of DNA technology in solving crimes in Australia. News.Medical.Net, (2008) Real concerns over the ethics of a DNA database , Interview, http://www.newsmedical.net/?id=34184 (15/05/2008) In this article, Professor Jeffreys -known as the father of DNA fingerprinting-spoke out over the 'significant ethical and social issues' as the UK Government launched an inquiry into the way the national DNA database is used. The UK database, with the DNA of over 4 million people, was launched in 1995 and allows all DNA collected by forensics- for whatever purposes- to be stored indefinitely. The writer of the article was not identified and that diminishes the credibility of the information posted as facts. Parliamentary Office of Science and T echnology (2006) The National DNA Database, www.parliament.uk/parliamentary_offices/post/pubs2006.cfm (19/05/08) This is an official informative article published by the United Kingdom‟s Parliamentary Office of Science and Technology about their national DNA d atabase. In contains statistics and information about how the DNA samples a re collected, stored and handled. Peri, T. (2008) Mr Peri’s Peri’s Bio -Image Gallery, http://www.ndpteachers.org/perit/biology_image_gallery1.htm (05/05/08) This source is an American school teacher‟s collection of useful biology -related images that may be useful to his students and others. As he is a teacher, his collection would have to be relevant and corr ect. Silverman, J. (2007) Has our DNA database gone too far? , http://news.bbc.co.uk/2/hi/uk_news/6979165.stm (19/05/08) This source is an article written by Jon Silverman, published by the BBC. It provides fairly recent statistical data concerning the national DNA database in t he UK. It also highlights some of the implications of having and securing a national DNA database and how the general public feel about it.


University of Leicester (2008). Concerns Over Potential Future Use Of DNA Of Innocents On National Database. ScienceDaily, http://www.sciencedaily.com/releases/2008/01/080111224007.htm (05/05/2008) In this article, Professor Sir Alec Jeffreys, of the University of Leicester, has voiced his concerns over the ethics of a DNA database. He was concerned that the database was being populated by people who had not been convicted of any crime. During a law lecture at the University of Leicester the Right Honourable Lord Justice Sedley, a senior appeal court judge, also highlighted concerns over the DNA database. This is a credible source from two highly respected individuals in the British community. University of Michigan Health System (2007). Parents Support Genetic Testing , DNA Biobanks, Study Finds. ScienceDaily, http://www.sciencedaily.com/releases/2007/06/070627143048.htm (10/05/2008) This article gives information on the National Poll on Children‟s Health conducted in the USA. This survey assessed the willingness of parents to have genetic testing on children to discover genetic predisposition to various diseases and also the willingness to store the DNA in a biobank for medical research. While genetic testing and DNA biobanks are promising new health care tools, they raise many ethical questions. Reluctance to participate in a DNA biobank reflect concerns about the potential for such information to lead to genetic discrimination that might affect a person's ability to get a job or be covered by health insurance. Legislation to prevent such discrimination, is a crucial step in helping to ease public fears about participation in DNA biobanks and about genetic testing overall. T his is a reliable university source. The University of Utah, Genetic Science Learning Centre (2008) Gel Electrophoresis, Macromedia Flash presentation http://learn.genetics.utah.edu/units/biotech/gel/ (03/05/2008) This web site shows an animation of electrophoresis to enhance understanding of the steps involved in the process of separating DNA fragments. This i s a reliable university source. ,

Ussery, D. (2000) Method #3: Gel Electrophoresis , http://www.cbs.dtu.dk/staff/dave/roanoke/genetics980211.html (28/04/08) This source is a website of course notes on genetics put together by a lecturer. The notes are for his students to study for their exam so it can be assumed that they are all correct. Numerous pictures provided good visual aids for this essay. Wikipedia (2008) Gel Electrophoresis, http://en.wikipedia.org/wiki/Gel_electrophoresis (28/04/08) Wikipedia (2008) Twins, http://en.wikipedia.org/wiki/Twins (17/05/08) Wikipedia is written collaboratively by volunteers from all around the world. With rare exceptions, its articles can be edited by anyone with access to the Internet. Since its creation in 2001, Wikipedia has grown rapidly into one of the largest reference Web sites on the Internet. Because Wikipedia is an ongoing work to which in principle anybody can contribute, it differs from a paper-based reference source in some very important ways. In particular, older articles tend to be more comprehensive and balanced, while newer articles may still contain significant misinformation, unencyclopedic content, or vandalism. Users need to be aware of this in order to obtain valid information and avoid misinformation which has been recently added and not yet removed. However, unlike a paper reference source, Wikipedia can be constantly updated, with articles on topical events being created or updated within minutes or hours, rather than months or years for printed encyclopaedias. This article specifically pertains to the process of electrophoresis, the different materials, chemicals and equipment used and its purpose in the judicial system. Williams, R. (2002) Genetic Fingerprinting, The Science Show, ABC Radio National http://www.abc.net.au/rn/scienceshow/stories/2002/679061.htm http://www.abc.net.au/rn/sciencesh ow/stories/2002/679061.htm (07 /07/2008) This is an interview with Professor Sir Alec J. Jeffreys, research scientist in the Department of Genetics at the University of Leicester, United Kingdom. In this interview he describes the events leading to the discovery of the DNA fingerprinting and the scientific implication of this discovery. Sir Jeffreys is an imminent scientist, knighted by the Queen for his services to science. He published numerous articles in peer-reviewed scientific journals.


DNA Fingerprinting

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