dna analysis dna typing (genotyping) – history –a marker is any polymorphic mendelian character...
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DNA analysis
• DNA typing (genotyping) – History– A marker is any polymorphic Mendelian
character that can be used to follow a chromosomal segment through a pedigree.
• Phenotypical markers: E.g. blood groups• Restriction Fragment Length Polymorphism
(RFLP) markers – The discovery of restriction enzymes not only provided a way to engineer the DNA, but for the first time, provided a marker that encompassed entire chromosome.
Forensics – DNA analysis
• RFLP– History– Southern analysis– Fragment length analysis– Frequency– Pattern used to identify individuals
Minisatellite Variable RepeatPolymorphism (Analysis)
First locus identified: D1S81990, Alec Jeffrey19 bp for each repeat containinghighly variable 1 bp in theHaeIII siteHundreds markers give sifficientpolymorphism
Forensics – DNA analysis
• Polymerase Chain Reaction (PCR) – Discovery– Principles– Application examples
• The case of the Russian Czar • The case of English Royals• Crime scene identification
1 2
2 4
3 8
4 16
5 32
6 64
7 128
8 256
9 512
10 1024
11 2048
12 4096
13 8192
14 16384
15 32768
16 65536
17 131072
18 262144
19 524288
20 1048576
21 2097152
22 4194304
23 8388608
24 16777216
25 33554432
26 67108864
27 1.34E+08
28 2.68E+08
29 5.37E+08
30 1.07E+09
Short Tandem Repeats
Forensics – DNA analysis
• Single Nucleotide Polymorphism - SNP
• Sequence Polymorphism – DQ1
Forensics – DNA analysis
Sequence Polymorphism
Consideration of Markers
• RFLP• DQ1 • STR (VNTR)• SNP
• Restriction enzymes• Blot • PCR• DNA micro array
Better PolymorphismIncreased DensityLess Sample AmountsEasier TestMore Expensive
•Length•Hybridization•Length•Hybridization
Finding Common Characteristics of elements---Can you find common characters in the following figures?1. These are “jollos”.
2. These are “plotz”.
3. Which are jollos and which are plotz?
A BC D E
“The bungledburglary” or“The burglarthat couldn’t”
The “missing person” case:
Using PCR based polymarkerloci GYPA, HBGG, D7S8, GCDQA1, STR TRIPLET.Gender identification locus:amelogenin
Suspect & roommate excludedfrom blood on carpet and shoes.Roommate excluded.Suspect pled to first degreemurder.
The gender IDmarker
The case of disappearing sperm:
DQ was the only locus validated forPCR testing in forensics at the time.
No conclusion can be drawn from the test results
The OJ Simpson case
This was a few years ago.
Now SNP typingmarker concentration= one million / genome
RFLP results
5 and 6; 7 and 9 areindistinguishable
The first RFLP case (State v. Tommy Lee Andrews)
1353
Lane 3: Victim controlLane 5: Vaginal swabLane 13: Andrew