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Fundamentals of Forensic DNA Typing

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Chapter 18 Future Trends Fundamentals of Forensic DNA Typing Slides prepared by John M. Butler June 2009 Chapter 18 Future Trends Chapter Summary As the power of ... – PowerPoint PPT presentation

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Title: Fundamentals of Forensic DNA Typing


1
Fundamentals of Forensic DNA Typing
Chapter 18 Future Trends
  • Slides prepared by John M. Butler
  • June 2009

2
Chapter 18 Future Trends
  • Chapter Summary
  • As the power of forensic DNA typing has been
    demonstrated over the past two decades, there has
    been an accelerated growth to the field both in
    terms of depth and breadth. National DNA
    databases in the UK and US now number in the
    millions of samples and are actively used to
    solve crimes without suspects. While the standard
    set of STR markers in use will not likely change
    in the immediate future, techniques and genetic
    markers capable of extracting more information
    from a sample will continue to be developed.
    Trends in human identity testing will likely
    include the need for more characterized and
    validated genetic markers to aid application to
    more complex kinship analysis. Continued growth
    can be expected for the foreseeable future in
    this dynamic and important application of modern
    DNA science.

3
Possible scenarios for extending sets of genetic
markers to be used in national DNA databases
Core set of markers (e.g., CODIS 13 STRs)
(a)
Past and Present
John M. Butler (2009) Fundamentals of Forensic
DNA Typing, Figure 18.1
(b)
Future
(c)
(d)
4
Primary Steps in Adopting New Genetic Markers
John M. Butler (2009) Fundamentals of Forensic
DNA Typing, Figure 18.2
5
Solution Additional Markers (Y-chromosome, more
STRs) and Multiple Reference Samples
Core Competency
Standard STR Typing (DNA Profile)
Familial Searching Attempts (fishing for brothers
or other relatives)
Direct Matching (or Parentage)
Sufficient DNA quantity (ng)
John M. Butler (2009) Fundamentals of Forensic
DNA Typing, Figure 18.3
Touch DNA Attempts (poor quality, mixtures,
low-level stochastic effects)
Solution Replicate Testing
6
Going Beyond the Core Competencies of Forensic
DNA Testing
Core Competency
Standard STR Typing (DNA Profile)
Familial Searching Attempts (fishing for brothers
or other relatives)
Direct Matching (or Parentage)
Sufficient DNA quantity (ng)
Solution Additional Markers (Y-chromosome, more
STRs) and Multiple Reference Samples
John M. Butler (2009) Fundamentals of Forensic
DNA Typing, Figure 18.3
Be very cautious when outside the box
Touch DNA Attempts (poor quality, mixtures,
low-level stochastic effects)
Solution Replicate Testing
7
Problems of Sibling Searches
(a)
(b)
Mother

s alleles
12
13
12,13
8,9
John M. Butler (2009) Fundamentals of Forensic
DNA Typing, Figure 18.4
8,
13
8,
12
8
s alleles
8,12
9,12

9,13
8,13
Father
9
9,
13
9,
12
8
A Crystal Ball to the Future?
http//medicalcenter.osu.edu/images/healthconnecti
ons/winter2003/dnaCrystalBallIllustration.jpg
9
Progress is Being Made
10
The DNA Field Moves Forward
The Future
The Past
The Present
http//www.bioteach.ubc.ca/MolecularBiology/DNAfin
gerprint/
STRs
SNPs
RFLP
miniSTRs
11
Lab Automation
  • Robotics
  • LIMS
  • Expert Systems

12
Unique Challenges with Adopting New Technologies
by Forensic DNA Laboratories
  • Validation
  • Limited funding for capital equipment
  • Need for court acceptance (Frye and Daubert)

13
Unique Challenges to Forensic DNA Testing
  • High quality results needed (every time) because
    of impact on individuals liberty
  • Regulated environment
  • Proficiency testing of analysts
  • Accreditation of labs
  • Auditing to National Quality Assurance Standards
  • Care to prevent contamination
  • The ever present politics and bureaucracy that
    exists in many government labs

14
Additional Challenges
  • Multiplex STR amplification require a fairly
    narrow amount of input DNA to product high
    quality results
  • High-throughput needs for databanking labs
  • Automated software for data review
  • An attitude of being (and needing to be)
    error-free
  • Separating biological fluids perpetrators
    sperm from victims vaginal epithelial cells
  • Mixture components can be difficult to decipher

15
General Predictions for the Future
  • Refer to The Future of Forensic DNA (NIJ 2000)
  • STRs will play a major role for the foreseeable
    future due to large sizes of existing and rapidly
    growing DNA databases

16
  • Report published in Nov 2000
  • Asked to estimate where DNA testing would be 2,
    5, and 10 years into the future
  • Conclusions
  • STR typing is here to stay for a few years
    because of DNA databases that have grown to
    contain millions of profiles

http//www.ojp.usdoj.gov/nij/pubs-sum/183697.htm
17
Principles of Forensic DNA for Officers of the
Court
  1. Introduction
  2. Biology of DNA
  3. Practical Issues Specific to DNA Evidence
  4. Forensic DNA Laboratory
  5. Assuring Quality in DNA Testing
  6. Understanding a Forensic DNA Lab Report
  7. Statistics and Population Genetics
  1. Mitochondrial DNA Y-STR Analysis
  2. Forensic DNA Databases
  3. Collection of DNA Evidence
  4. Pretrial DNA Evidence Issues
  5. Victim Issues
  6. Trial Presentation
  7. Postconviction DNA Cases
  8. Emerging Trends

http//www.dna.gov/training/otc/
18
Content of Section 15 Emerging Trends from
Officers of the Court
  • Topic 1 Single Nucleotide Polymorphisms (SNPs)
  • Topic 2 Automation
  • Microarrays (Chip Technology)
  • Portable DNA Typing Laboratory
  • Low Copy Number DNA Analysis
  • Topic 3 Microbial Forensics and DNA Testing
  • Topic 4 Other Non-human Forensic DNA Analysis
  • Topic 5 DNA Typing and Physical Appearance
  • Biogeographical Ancestry
  • Approximate Age Determination

http//www.dna.gov/training/otc/
19
The Future
  • More Robotics
  • Expert Systems
  • Animal Plant DNA
  • Physical Characteristics
  • Ethnicity Estimation

20
Time Line Showing the Potential for DNA
Deposition/Transfer
Higher sensitivity techniques are most likely to
pick up previously deposited (background) DNA
Time
Adapted from Gill, P. (2002) BioTechniques 32(2)
366-385, Figure 5
21
Conclusions
  • This is an exciting time to be involved in
    forensic DNA testing
  • However, it is a little scary because technology
    is advancing so rapidly on some fronts
  • Thus, training for both the scientific and legal
    communities is vital to make the most effective
    use of the wonderful power of DNA technology

22
Improvements in Forensic DNA Analysis
  • Biology
  • Improved DNA extraction with automation
  • New capabilities for recovery of information from
    degraded DNA samples (e.g., miniSTRs)
  • Technology
  • Parallel processing of DNA with capillary arrays
  • Expert systems for automated data interpretation
  • Genetics
  • Ethnicity estimations (with STRs and/or SNPs)
  • Larger Y-STR and mtDNA population databases

Effective Training is Needed in All Areas
23
Training Materials Available or Planned
  • DNA Basics
  • Validation
  • STR Analysis and Capillary Electrophoresis
  • Y-Chromosome Analysis
  • Mitochondrial DNA Analysis
  • Expert Systems
  • Low-Copy Number (LCN) DNA Testing
  • Statistics
  • Mixture Interpretation

http//www.cstl.nist.gov/biotech/strbase/training.
htm
24
Training Materials and Review Articles
  • Workshops on STRs and CE (ABI 310/3100)
  • Taught with Bruce McCord (Florida Int. Univ.)
  • NEAFS (Sept 29-30, 2004)
  • U. Albany DNA Academy (June 13-14, 2005)
  • AAFS Feb 2006 Workshop 6 (February 20, 2006)
  • Other Workshops
  • Validation (August 24-26, 2005)
  • mtDNA Analysis (March 13-15, 2006)
  • Expert Systems (March 27, 2006)
  • PowerPoint Slides from Forensic DNA Typing, 2nd
    Edition
  • gt150 slides available now (1,000 planned) for
    download
  • http//www.cstl.nist.gov/biotech/strbase/FDT2e.htm
  • Review Articles
  • ABI 310 and 3100 chemistry Electrophoresis
    2004, 25, 1397-1412
  • Core STR Loci J. Forensic Sci. 2006, 51(2)
    253-265

http//www.cstl.nist.gov/biotech/strbase/training.
htm
25
Chapter 18 Points for Discussion
  • What are some potential advantages to microchip
    CE devices?
  • Why are allelic ladders unnecessary with mass
    spectrometry techniques for STR analysis?
  • Why are forensic laboratories typically slow to
    adopt new technologies?
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