DNA Forensics

How DNA is used How DNA is used

Ethical Issues Ethical Issues

By : Daniel DiCenzoBy : Daniel DiCenzo

What is DNA?

• DNA - Deoxyribonucleic acid• DNA is the blueprint for the design of our bodies• Consists of certain base pairs that form specific sequences• These sequences can code for specific amino acids• These amino acids combine

to form proteins • The proteins together make

our entire body • Everyone’s DNA is unique• DNA holds all of the information

needed to make living things

What is DNA used to do?

• Code for amino acids in our bodies• Act as a bar code that identifies who we are (DNA

Fingerprint)• DNA can be analyzed and compared to other

DNA • Comparing DNA can be used for many purposes • To match and analyze people’s DNA, scientists

must perform special tests

• There are many ways to process DNA • Polymerase Chain Reaction (PCR)• Restriction Fragment Length Polymorphism

(RFLP)• Short Tandem Repeat (STR)• Mitochondrial DNA (mtDNA)

– DNA is taken from mitochondrion instead of nucleus

What Are These Tests

Polymerase Chain Reaction

• To put it simply PCR’s are used to amplify a certain piece of DNA

• The initial piece of DNA is separated into two strands• RNA primer is attached at specific spot on DNA• DNA polymerase adds base pairs to both single stranded

DNA• The product is two identical pieces of double stranded DNA• This process is repeated many times to achieve a large

amount of DNA• The amount of DNA produced after every cycle however

increases exponentially• This process allows a large amount of DNA to be produced

from only a minute sample collected

http://campus.queens.edu/faculty/jannr/Genetics/images/http://campus.queens.edu/faculty/jannr/Genetics/images/dnatech/FG12_11cPCR2.JPG dnatech/FG12_11cPCR2.JPG

Restriction Fragment Length Polymorphism

• DNA is cut at specific points into fragments• These fragments are then put in a gel • Via “gel electrophoresis” the DNA fragments

travel across the gel and stop at specific distances

• DNA can be compared to other DNA run through this same method

• This process however requires a large amount of DNA sample

http://www.ars.usda.gov/pandp/docs.htm?docid=11828 http://www.ars.usda.gov/pandp/docs.htm?docid=11828

Short Tandem Repeat

• Example of a tandem repeat• TAAGCTAAGCTAAGCTAAGC• In this tandem repeat – TAAGC is repeated four times• Every person’s DNA contains these tandem reapeats• These are inherited from your mother and your father• These are used in identification because they are very

unique in individuals• Scientists analyze 13 loci in our DNA, this prevents any

doubt that someone else shares these same genes• If only 2 loci are analyzed the probability that someone else

shares those genes are much higher which is not effective in identifying people using DNA

What are these fingerprints used for?

• DNA fingerprinting has many uses• DNA fingerprinting has the ability to:• Prove someone is guilty/innocent of a crime• Instantly find the culprit if they are in a DNA

database• Identify unknown bodies (old or new)• Determine who the father of a baby is (Paternity

Test)• Find an organ match for a person• Catch poachers hunting and selling the meat of

endangered animals

Ethical Issues

• DNA identification Act (1998)– Forces all those in Canada who have been convicted of a

certain crime to be entered into the National DNA Databank (NDDB)

• This is also the case in the U.S. – In 1998, all 50 states used their DNA databank, known as

the National DNA Index System (NDIS)• Having to be forced to provide DNA is a violation of human

rights, even if you are a criminal• Many believe in the future, everyone’s DNA will be on file• All of our most valuable secrets are exposed• Many believe this is an invasion of privacy• Our DNA can predict how we will die, do we want that

information?

Genetic Discrimination

• DNA holds secret to almost every weakness you have

• By allowing Insurance companies, employers, schools or banks access to any illness or flaw that you will, may or already have, you can be denied instantly

• Government can learn anything about you without your consent

• Those with “Good” DNA will be given better opportunities and success than those with “Bad” DNA

• This will lead to a new discrimination, not by race or religion, but by your DNA

Is DNA fingerprinting Reliable?

• People have come to believe that DNA evidence is indisputable in courtrooms (Too much faith in DNA)

• Human error is always a factor– Contamination of evidence – Labs are too pressured by police to give them the

evidence they want to close the case

• With more strict regulations on the quality of labs and technological advances, human error will be greatly reduced

• Planting of evidence is a new problem– This always leaves doubt into the reliability of DNA

evidence

• Must look for probable cause in a case and not rely solely on DNA evidence

DNA Databanks

• There are approximately 200 000 people in the Canadian National DNA Databank

• To this date there have been 10 000 offender hits because of this system

• In the U.S., 6.5 million people have been entered into their national DNA databank

• This databank is the largest in the world and has participated in over 77 000 investigations

http://www.nddb-bndg.org/stats_e.htm

Taken from NDDB statistics pageTaken from NDDB statistics page

Taken from NDDB annual report for 2006/2007Taken from NDDB annual report for 2006/2007

http://www.nddb-bndg.org/an_report_e.htm

Conclusion

• DNA holds all of the secrets of our bodies• There are many ways that DNA can be used to

identify and learn about other people• It is an effective tool in crime solving• The use of DNA databanks has caused major

concern over the civil rights of convicted felons and possibly in the future, the civil rights of everyone

• If people’s DNA is exposed, there is concern for our privacy being violated

Bibliography

• Federal Bureau of Investigation. (2008). CODIS – NDIS Statistics. Retrieved December 9, 2008, from: http://www.fbi.gov/hq/lab/codis/clickmap.htm

• Fink, Sheri. (2006, July). Reasonable Doubt. Discover, 27(7), 54-59. Retrieved from EBSCO host database.

• Fridell, Ron. (2001). DNA Fingerprinting The Ultimate Identity. Toronto: Franklin Watts.

• Genge, N.E. (2002). The Forensic Casebook. New York: Ballantine Publishing Group.

• Human Genome Project Information. (2008). DNA Forensics. Retrieved November 10, 2008, from: http://www.ornl.gov/sci/techresources/Human_Genome/elsi/forensics.shtml#1

• Lampton, Christopher. (1991). DNA Fingerprinting. Boston: Christopher Lampton. • Learn Genetics. (2008). Can DNA demand a verdict?. Retrieved December 1,

2008, from: http://learn.genetics.utah.edu/content/labs/gel/forensics/• National DNA Databank. (2006). Welcome to the National DNA Databank Website.

Retrieved November 20, 2008, from: http://www.nddb-bndg.org/main_e.htm • Zonderman, Jon. (1990). Beyond the Crime Lab. Toronto: John Wiley and Sons.