7th QIAGEN Investigator Forum - Lisbon, March 8, 2018 . An Approach to De-convolution of Mixtures in Touch DNA Samples. Presenter: Lisa Dierig, Institute of Legal Medicine, Ulm

1. An Approach to De-convolution of
Mixtures inTouch DNA Samples
Lisa Dierig, Institute of Legal Medicine, Ulm
7th Qiagen Investigator Forum, Lisbon, March 8, 2018

2. An approach to de-convolution of mixtures in touch DNA samples | Lisa Dierig | Institute of Legal Medicine, Ulm | March 8, 2018, Lisbon 2
Touch DNA
„Every contact leaves a trace“
Dr. Edmond Locard
• Minute amounts of (degraded) DNA
• Admixed profiles
• Unbalanced peaks
• Stochastic effects
http://clipart.coolclips.com/480/vectors/tf05156/CoolClips_vc007427.png

3. An approach to de-convolution of mixtures in touch DNA samples | Lisa Dierig | Institute of Legal Medicine, Ulm | March 8, 2018, Lisbon 3
Touch DNA
• Case scenario: Physical assault
• „Blind swabbing“
• Collection of single (skin) bioparticles
Aim:
Prevention of admixed profiles and improving DNA quantity
http://www.hollowaylawgroup.com/public
/uploads/cms/151008072833_icon11.png

4. An approach to de-convolution of mixtures in touch DNA samples | Lisa Dierig | Institute of Legal Medicine, Ulm | March 8, 2018, Lisbon 4
Mock case scenario

5. An approach to de-convolution of mixtures in touch DNA samples | Lisa Dierig | Institute of Legal Medicine, Ulm | March 8, 2018, Lisbon 5
Sample collection
Adhesive film

6. An approach to de-convolution of mixtures in touch DNA samples | Lisa Dierig | Institute of Legal Medicine, Ulm | March 8, 2018, Lisbon 6
Microscopic examination
1 mm
Microscope
https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTw7ftVr7FQxT73fG48PXCjT2SjqDTw-z3SmyE7L8bMfEgSSkXr

7. An approach to de-convolution of mixtures in touch DNA samples | Lisa Dierig | Institute of Legal Medicine, Ulm | March 8, 2018, Lisbon 7
Downstream analysis
• 5% Chelex + Proteinase K
• qPCR (Quantiplex® Pro)
• Low-Template PCR (ESSplex SE QS)
• ABI 3130, POP7
Lysis (Chelex)
Quantification
Low-template
PCR
CE
http://www.hsc.edu.kw/RCF/Images/ABI3130.jpg
https://www.qiagen.com/us/shop/detection-solutions/human-identity/investigator-essplex-se-qs-kit/#orderinginformation

8. An approach to de-convolution of mixtures in touch DNA samples | Lisa Dierig | Institute of Legal Medicine, Ulm | March 8, 2018, Lisbon 8
Staining of bioparticles

9. An approach to de-convolution of mixtures in touch DNA samples | Lisa Dierig | Institute of Legal Medicine, Ulm | March 8, 2018, Lisbon 9
Staining of bioparticles
before after
1 mm

10. An approach to de-convolution of mixtures in touch DNA samples | Lisa Dierig | Institute of Legal Medicine, Ulm | March 8, 2018, Lisbon 10
Staining of bioparticles
Pro
• Time saving
• Greater visibility → mainly smaller cells
before after
1 mm

11. An approach to de-convolution of mixtures in touch DNA samples | Lisa Dierig | Institute of Legal Medicine, Ulm | March 8, 2018, Lisbon 11
Staining of bioparticles
Pro
• Time saving
• Greater visibility → mainly smaller cells
Contra
• Toxic reagent
• Risk of contamination
before after
1 mm

12. Collection of cells on
adhesive film
Single skin cells/clumps
selection
Swabbing of
small areas
An approach to de-convolution of mixtures in touch DNA samples | Lisa Dierig | Institute of Legal Medicine, Ulm | March 8, 2018, Lisbon
Optimization of cell collection method
Increasing DNA quantity without generating admixed profiles
12

13. An approach to de-convolution of mixtures in touch DNA samples | Lisa Dierig | Institute of Legal Medicine, Ulm | March 8, 2018, Lisbon 13
Optimization of collection method
Single cells
(n=206)
Areas
(n=156)
negative 74% 3%
< 1 pg/μl 22% 71%
1-2 pg/μl 2% 15%
>2 pg/μl 2% 11%
Outliers >6 pg/μl not shown
Increase of DNA quantity

14. An approach to de-convolution of mixtures in touch DNA samples | Lisa Dierig | Institute of Legal Medicine, Ulm | March 8, 2018, Lisbon 14
Optimization of collection method
n=5 n=22 n=18

15. An approach to de-convolution of mixtures in touch DNA samples | Lisa Dierig | Institute of Legal Medicine, Ulm | March 8, 2018, Lisbon 15
Optimization of collection method
13 database entries possible
Profiles
(n=41)
Major offender 35
Major victim 2
Inconclusive 4
> 1 pg/µl partial profiles
> 2 pg/µl database entry possible

16. An approach to de-convolution of mixtures in touch DNA samples | Lisa Dierig | Institute of Legal Medicine, Ulm | March 8, 2018, Lisbon 16
Summary
• Improvement of visibility
oMicroscopic technique
oStaining with trypan blue
• New collection and analysis method
oLess mixtures than expected
oIdentification of offender
oFrom 1 pg/µl partial profiles → from 2 pg/µl database entry
possible
oCaution: artifacts!

17. An approach to de-convolution of mixtures in touch DNA samples | Lisa Dierig | Institute of Legal Medicine, Ulm | March 8, 2018, Lisbon 17
Future prospects
• Varying scenarios
oAdditional victim/offender combinations
oSame-sex mixtures
oMixtures with 2+ donors
oSkin-skin contact
oDifferent items
• Narrowing down the swabbing area

18. Thank you for your attention!
An approach to de-convolution of mixtures in touch DNA samples | Lisa Dierig | Institute of Legal Medicine, Ulm | March 8, 2018, Lisbon 18
Lisa Dierig
Institute of Legal Medicine
University Hospital Ulm
Albert-Einstein-Allee 23
89081 Ulm, Germany
E-mail: lisa.dierig@uniklinik-ulm.de
Phone: +49 731 500 65033