Fingerprints have been used since 1901

Fingerprints? DNA Fingerprints !

DNA Fingerprints since 1986

Examples of DNA in the News

President Clinton & Monica

Saddam Hussein Identification

Identification of WTC Victims

Examples of DNA in the News

President Jefferson & Hemings

内容

• Part A. Overview of Forensic DNA Analysis

• Part B. Short Tandem Repeats(STR) & STR-PCR

• Part C. Y Chromosome & Forensic Science

Outline of Presentation

• Two

Purpose of Forensic DNA Analysis

• Four

Applications of Forensic DNA Analysis

Overview of Forensic DNA Analysis

Part A

Purpose of Forensic DNA Analysis

Personal Identification Paternity Testing

JudicialJudicialLaw Enforcement

Laboratory

Applications of Forensic DNA Testing

Identify a person

Exclude suspects

Criminal scene

Suspect1 Suspect2 Suspect3

Matching su

spect

with

evidence

Matching su

spect

with

evidence

Applications of Forensic DNA Testing

?

Missing perso

ns investi

gations

Missing perso

ns investi

gations

Applications of Forensic DNA Testing

Paternity

testi

ng - identify

ing

father

Paternity

testi

ng - identify

ing

father

Applications of Forensic DNA Testing

Mass disa

sters

- putti

ng pieces b

ack

together

Mass disa

sters

- putti

ng pieces b

ack

together

Personal IdentificationPaternity Testing

Matching suspect with evidenceMissing persons investigations

Paternity testing - identifying fatherMass disasters - putting pieces back together

1. Purpose of Forensic DNA Analysis

2. Applications of Forensic DNA Testing

2P2P

3M1P3M1P

Summary for Part A

Coming soon……Coming soon……Coming soon……Coming soon……Coming soon……

Part B

Short Tandem Repeats(STR) & STR-PCR

• The Molecular Structure of DNA

• What is Short Tandem Repeats(STR)?

• The Allele Nomenclature of STR

• The Nomenclature of STR

• The Principles of STR-PCR

• Application of STR-PCR

The Molecular Structure of DNA

homologous

Short Tandem Repeats (STRs)

……

Individual 1

Individual 2

Individual 3

…CTAGTCGT(GATA)(GATA)(GATA)GCGATCGT…

…CTAGTCGT(GATA)(GATA)(GATA) (GATA) GCGATCGT…

…CTAGTCGT(GATA)(GATA)(GATA) (GATA) (GATA) GCGATCGT…

The repeat region is variable between samples while the flanking regions where PCR primers bind are constant

The number of repeat unit

Short Tandem Repeats (STRs)

7 repeats

8 repeats

AATGAllele Nomenclature

8

7

TCAT repeat unitTCAT repeat unit

STR Sequence from GenBank

D5S818

D21S11D13S317

D7S820

D16S539 D18S51

D8S1179

D3S1358

Nomenclature of STR

D10S2325

D12S391

D1S549

DYS630

DXS1056

Target Region for STR-PCR

Target Region for STR-PCR

A process mediated by a DNA polymerase that can yield millions of copies of a desired DNA sequence

Polymerase Chain Reaction (PCR)

STR with the Polymerase Chain Reaction (PCR)

Applications of STR-PCR

Father’s Sperm

Mother’s Egg

Child’s CellOur D

NA Comes from our

Parents

Our DNA Comes f

rom our

Parents

Applications of STR-PCR

Family Inheritance of STR Alleles (D13S317)

Suspect Father

Confirmed Mother

11-14

12-14

8-14

11-12

8-12

Locus Suspected-Father Confirmed-Mother ChildD8S1179 13-16 12-13 12-14D5S818 9-11 10-11 10-12D1S549 13-14 14-15 13-14D3S1754 14-15 13-13 13-14

Applications of STR-PCR

D8S1179 13-16 12-13 12-14D5S818 9-11 10-11 10-12

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……

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×

×

Exclusio

n ！Exclusio

n ！

Exclusio

n ！Exclusio

n ！

Coming soon……Coming soon……Coming soon……Coming soon……Coming soon……Coming soon……Coming soon……Coming soon……Coming soon……Coming soon……Coming soon……

Part CY Chromosome & it’s Application in

Forensic Science

The Human Genome

Characteristics of Human Y chromosome

Father to son & Male-specificDad made you a boy or

girl

Dad made you a boy or

girl

Y chromosome’s application in Forensic Science

Deficiency Paternity Testing

Sexual Assault Cases

Historical Investigations

?

Thomas Jefferson fathered slave’s children

Thomas Jefferson fathered slave’s children

Failure to Exclude Jefferson as Eston Hemings’ Father

Failure to Exclude Jefferson as Eston Hemings’ Father

?

×

Identical !

SUMMARY

1. Purpose of Forensic DNA Analysis

2. Applications of Forensic DNA Testing

3. What is Short Tandem Repeats(STR)?

4. The Principles of PCR

5. Characteristics of Human Y chromosome

2P2P

3M1P3M1P

Questions ?

What’s the difference

between

Autosomal STR and Y-chromosomal STR?

Thanks for your attention!