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 Repeat Polymorphism (Analysis) First locus identified: D1S8 1990, Alec Jeffrey 19 bp for each repeat containing highly variable 1 bp in the HaeIII site Hundreds markers give sifficient polymorphism

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

E E E E+09

Short Tandem Repeats

Forensics – DNA analysis Single Nucleotide Polymorphism - SNP Sequence Polymorphism – DQ  1 Forensics – DNA analysis

Sequence Polymorphism

Consideration of Markers RFLP DQ  1 STR (VNTR) SNP Restriction enzymes Blot PCR DNA micro array Better Polymorphism Increased Density Less Sample Amounts Easier Test More 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? AB C DE

“The bungled burglary” or “The burglar that couldn’t”

The “missing person” case: Using PCR based polymarker loci GYPA, HBGG, D7S8, GC DQA1, STR TRIPLET. Gender identification locus: amelogenin Suspect & roommate excluded from blood on carpet and shoes. Roommate excluded. Suspect pled to first degree murder.

The gender ID marker

The case of disappearing sperm: DQ  was the only locus validated for PCR 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 typing marker concentration = one million / genome

RFLP results 5 and 6; 7 and 9 are indistinguishable

The first RFLP case (State v. Tommy Lee Andrews) Lane 3: Victim control Lane 5: Vaginal swab Lane 13: Andrew