FORENSICS Cabanto, Ecat, Talampas, Vocal, Beleran, Mina IV-Gluon
Jan 17, 2016
FORENSICS
Cabanto, Ecat, Talampas, Vocal, Beleran, Mina
IV-Gluon
DNA fingerprinting: Overview
1984 - Sir Alec Jeffreys Also known as genetic fingerprinting or
DNA profilingWay of identifying an individual*Applications
ForensicsPaternity/Maternity tests
Why it is better than a fingerprint.
Fingerprints are easily obscuredDNA is in every cell of the body
Hair strandSkin follicleDrop of blood
How it works
99.9% of our genes are identicalThe remaining 0.1% is used to determine
the individualMicrosatellites
Short repetitive sequences that are highly variable in humans
Reflect individual genetic make-upA.k.a. Variable Number Tandem Repeats
(VNTR)
VNTR’s
short sequence in the introns of DNA that is repeated in a head-to-tail manner at a specific chromosomal locus
interspersed in genomeNumber of repeated units vary per humanLoci – VNTR’s
One VNTR – 17 bp, repeated 70 to 450 timesTotal: 1190 to 7650 base pairs
Southern hybridization
DNA with VNTR is cut with a restriction endonuclease
Size varies, creating RFLPs, or restriction fragment length polymorphisms
Analysis
Leads to a two-band pattern
Inherited from each parent
One band can occur if parental bands are identical/nearly the same
Basic Genetic Principles
Identity matching VNTR alleles should be the same if samples
are from the same individual.
Inheritance matchingHe or she could have VNTRs inherited from
his or her mother or father, or a combinationNever a VNTR either of his or her parents do
not have.
Other Uses
Personal IdentificationCasualtiesPaternity/Maternity testingFamily reunions yehey :D
Other Uses
Diagnosis of inherited disordersAlzheimer’s diseaseHuntington’s disease
Determining risks of having an affected child
Identify patterns associated with diseaseMay lead to cure for the disorder
Other Uses
Mapping genographyFind patterns of migrationTrace human species’ history
National Geographic SocietyStudy distinct trail left by humans since we left
AfricaUnderstand more about our background
In the Philippines
Case study: Ray de VillaJan. 9, 1995- Arrested for the rape of 13
yo nieceDNA testing was not done at that timeSole evidence was birth of a childCounter evidence – 76 yo suspect
suffered physical condition
Case Study
Victim did not report assault until confronted of pregnancy
Problem: Court did not allow paternity testing
Dr. Cora de Ungria of UP devised a way to be able to profile the child’s paternity
Both parties (child’s family and prison) refused for samples
“Spitting game” to get saliva from child and 4 other children
Blood from De Villa without assistance from prison staff
Results: genetic markers proved that De Villa could not have fathered any of the children
Parole was granted to De Villa after extensive legal action
Since then, Philippine Parliament has introduced DNA database legislation and the Supreme Court has issued rules for the admission of DNA profiling results in court
UP Diliman’s DNA analysis lab has also created a “rape kit”- Sexual Assault Investigation Kit for the Collection of Biological Samples
In the Philippines
Crop biologyanalysis of genetic diversity within breeding
populations in plantsDifferentiation between cultivarsIdentification of plants containing a gene of
interest
Issues
Privacy of suspectsStudies regarding human populationDNA evidence may place a person at a
crime scene, but it also does not necessarily mean that he or she committed the crime
DNA can still be tampered with, and still be used to frame people
Issues
Pattern narrows down a million people to around 2-10
Sometimes cannot identify individualHowever, if there are suspects in hand,
the match can be easily made