Download forensics - bayo2pisay

FORENSICS
Cabanto, Ecat, Talampas, Vocal,
Beleran, Mina
IV-Gluon
DNA fingerprinting: Overview
1984 - Sir Alec Jeffreys
Also known as genetic fingerprinting or
DNA profiling
Way of identifying an individual*
Applications
Forensics
Paternity/Maternity tests
Why it is better than a fingerprint.
Fingerprints are easily obscured
DNA is in every cell of the body
Hair strand
Skin follicle
Drop of blood
How it works
99.9% of our genes are identical
The remaining 0.1% is used to determine
the individual
Microsatellites
Short repetitive sequences that are highly
variable in humans
Reflect individual genetic make-up
A.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 genome
Number of repeated units vary per human
Loci – VNTR’s
One VNTR – 17 bp, repeated 70 to 450 times
Total: 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 matching
He or she could have VNTRs inherited from
his or her mother or father, or a combination
Never a VNTR either of his or her parents do
not have.
Other Uses
Personal Identification
Casualties
Paternity/Maternity testing
Family reunions yehey :D
Other Uses
Diagnosis of inherited
disorders
Alzheimer’s disease
Huntington’s disease
Determining risks of having an affected
child
Identify patterns associated with disease
May lead to cure for the disorder
Other Uses
Mapping genography
Find patterns of migration
Trace human species’ history
National Geographic Society
Study distinct trail left by humans since we left
Africa
Understand more about our background
In the Philippines
Case study: Ray de Villa
Jan. 9, 1995- Arrested for the rape of 13
yo niece
DNA testing was not done at that time
Sole evidence was birth of a child
Counter 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 biology
analysis of genetic diversity within breeding
populations in plants
Differentiation between cultivars
Identification of plants containing a gene of
interest
Issues
Privacy of suspects
Studies regarding human population
DNA 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 individual
However, if there are suspects in hand,
the match can be easily made