Casework GO!

• what is casework go!

  • about rapid detection of male DNA in SA
  • it is the lysis step in DNA extraction
• compare 2 types of extraction techs

  1. silica column based: perform cell lysis in a solution, apply it to the column, and unwanted part of the matrix flows through while wanted is bind.

  2. paramagnetic: magnetic core is coated with silica membranes. separation of mag particles occur when mag is applied.

  • it has a wider SA for attachment and thus covers lots of DNA
• what does the FSQ use for extraction

  1. DNA IQ
  2. prep vfiler

  • both are magnetic based
• list the process of paramagnetic based extraction

  1. pre-lysis
  2. incubate with mag particles for DNA to bind
  3. lysis: use mag to pull non-mat to 1 side to dispose remaining solution
  4. washing
  5. repeat
• what does DNA extraction allow

  • to determine how to use dna profile
• what are some challenges to this method

  • DNA can be lost!!!

  1. continuously changing the pipette tips and tubes
  2. multi washes (column: 3 and DNA IQ:2)
• direct PCR

  • FTA cards <- DNA is already stuck and lysised due to chemical on card
  • used for reference samples
• what’s the problem with direct PCR

  w/o washing, the DNA is not purified and contamination is removed

  ie. heam in blood = inhibitor which = poor separation
• list the steps for SA sample collection

  1. medical exam
  2. evidence collection with swab <- stored for 12 months
  3. FECK <- forensic evidence collection kit
  4. delivered to the centre
• what is the process when the swabs are submitted

  1. FECK swabs undergo: colourimetric(colour change of AP =purple) and immunological

  2. prepare slides for confirmatory test

  3.sperm searcher AI and 1 reader

  4. reader 1 and reader 2

  5. consensus
• what is the new process for the swabs of SA

  1. cut a small piece of SAIK
  2. use GO! for lysis
  3. 30 min lysis for DNA isolation
  4. use quantified trio quant
  5. detect Y target
• List the steps for CWG-Y-screening

  1. Add sample
  2. add CWG master mix
  3. vortex
  4. spin
  5. incubate 60 degrees for 25 minutes
  6. incubate 80 degrees for 5 minutes
  7. spin
  8. detect Y-target quantification using quantified trio kit
  9. lysate
• notes about the go! method

  • only work in batches of 12
  • DI: degradation index b/w 1-2.5 = DNA is intact
  • DI > 2.5-4 = DNA mildly intact
  • DI 4+ = DNA degreaded
  • in differential aMp, LA target are more prone to effect of inhibitors
• explore sperm score 


  0:none

  +<5: very low

  +: low

  ++: medium

  +++: high and abundant
• list things that go! included and excluded

  included:

  • low and around limit of detection
  • compounds like lube that can interfere with Y-screen test

  excluded:

  • digital rape or AP30 absent
  • single swab of FECK
  • immunological test
  • victim is a minor or vulnerable
  • no suspect nominated
  • cold cases