Quant Analysis
EPG Trouble Shooting

Define the targets in QT:





Small= amp targeting

Large= degredation

Male= YSTR targeting

IPC= checks for inhibitors/the rxn worked.


What is ILS? What would happen if ILS isn't added to a tray?

ILS is the internal lane standard that sizes the length of the unknown DNA fragment.

If ILS isn't added, then the data would not be able to size correctly, and may not show up.


What's the difference between random and systemic contamination?

Random= one single RB or sample

Systemic= Multiple samples/RBs affected


What are the conclusion requirements for a single source profile?

Under 3 alleles= INC

3 alleles= Inclusion

3+ Loci= Exclusion


Who is Bode Accredited by?

-ISO 17025



What does a high or low Ct mean?

High= reaction worked, DNA is not degraded

Low= degraded sample, or too much DNA template


What is the purpose of a ladder?

The ladder provides the allele calls for the unknown peaks. If ladder isn't added properly, the peak will not be called, or will be all OL.


What if an RB passes per SOP?

1. Attempt to Source

2. Determine if random or systemic

3. Random= RB passes, case note

4. Systemic= RB fails, reprocess all processed in parallel. No TL for new data, case note


What do we use RMP for and why?

Single Source inclusions, because it follows the product rule of independent assortment.

What is ST/AT for all amp kits?

GF: 600, 125

PPF: 500, 100

6C: 600, 100

24plex: 600, 100


What does it mean when IPC flags? with a large DI? Large DI and no IPC flag?

That the sample is inhibited. The sample is inhibited and degraded. That the sample isn't inhibited but is degraded.


What is stutter? What is the N and the -X?

Stutter is caused by an amplification error where the template bulges out and a repeat is either added or not included. 

N=true allele peak

-4= minus one repeat, -4bp behind the true peak


What if an RB fails per SOP?

Attempt to source and determine if random or systemic. 

Systemic= RB and associated samples fail. Reprocess

Random= Check quant data


What is CPI and why do we use it?

CPI is used for mixture statistics that were not able to be deduced to single source. They are more conservative because they don't use product rule.


What is the purpose of Y Markers in STR kits? and Yindel?

-Can be used to determine a male profile if Y is null

-Yindel is a shorter polymorphism that men have either an insertion 1 or deletion 2


What if the IPC flags with a quant value?

There's too much template DNA


What do you check when deciding to reload/amp/inject?

-Check what went wrong

-amp target, reagent issue, instrument issue


What if the RB/Sample quant doesn't indicate contamination?

1. Reload

2. Reamp

3. Reextract

if contamination is gone, then can report data. If not, data fails and scrutinize data to determine if impacted.


Which locus are suitable for stats?

SS: all locus with a pair or 2p rule for one allele at a locus

Mix: 3+ all locus over ST, 2 if all alleles are accounted for


Define and identify Stochastic Effects

When other alleles/loci are preferably amplified over others resulting in drop out and alleles under ST


How to troubleshoot high female profile in SF

-ProK spike


-try to deduce


What's required for a foreign mixture worksheet?

-2 person mix

-body swab

-need a reference sample


How to source Contamination

1. Check GMIDX

2. Check BodeMatch if it's a known contaminate

3. If sourced, check steps of coprocessing to determine when it occurred.


What are conclusion requirements for a mixture?

Inclusion: 3+ complete alleles

Exclusion: Represented at 3+ loci

INC: Under 3 loci


What are the RB passing guidelines

GF/PPF/6C: no more than 1 peak over AT, or up to 3 peaks under AT and one under 250rfu

24plex: no more than 3 peaks under AT