Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

FSCI6370 - DNA > Benefits of Modern DNA Multiplexes > Flashcards

Benefits of Modern DNA Multiplexes Flashcards

1
Q

What do forensic DNA tests look at?

A
  • multiplexes - combination of several areas (locus/loci) of DNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

When are alleles said to match?

A
  • when their peaks fall at the same position on the EPG
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What was the test to produce DNA profiles when the national DNA database was set up in 1995?

Why was this not favoured for that long?

A
  • Second-Generation Multiplex (SGM)
  • comprised of 6 loci and AMEL test (indicating sex)
  • there was a case of mistaken identity in 1999
  • a six loci match (1 in 37 million)
  • additional loci would have excluded the individual
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What was the test used to provide DNA profiles for the UK DNA database in 1999?

A
  • Second-Generation Multiplex + (SGM+)
  • number of loci increased to 10
  • all of SGM loci plus AMEL so test was back-compatible with previous multiplexes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Give a timeline of 1985 to 2014

A

1985 - MLP
1990 - SLP
1994 - STR - Quad
1995 - SGM
1999 - SGM+
2014 - DNA17

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the three types of DNA match?

A

1 - person to crime
- between reference sample and undetected crime

2 - crime to crime
- investigative link between two crimes (useful in undetected crimes)

3 - person to person
- between reference samples
- means duplicates been identified (different names but same person)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What was the new method to produce DNA profiles introduced in the UK in 2014?

What are the reasons as to why this was developed?

A
  • DNA17
  • requests from police and investigators for undetected DNA profiles to be searched against databases from other countries
  • easy to travel between countries means can escape abroad
  • to deal with cross-border and inter-country crime
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the six search requests within Europe?

A
  1. related to terrorist incidents
  2. trafficking of people
  3. drugs smuggling
  4. people smugglers
  5. serious crimes
  6. identification of missing persons and mass disasters
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

When can non-concordance occur?

A

if a crime stain is profiled using one multiplex and a reference samples uses a different one so they might not match

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is a near match report system?

A
  • it is used to identify individuals who may not have an exact match to the DNA profile from the crime scene but share significant similarities
  • it lists one allele differences between profiles
  • it can be extended to investigate two or three allele differences between reference samples if needed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is concordance?

A
  • the agreement or match between two DNA profiles obtained from the same individual or from related individuals
  • analysts look for concordance to determine whether the profiles match sufficiently to conclude that they originate from the same source
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are three reasons for non-concordance?

How can one of these by overcome?

A

1 - data entry error (typing incorrect number)
2 - sometimes the profiles can be very similar
3 - mutation (crime stain is profiled using one multiplex and the reference is a different multiplex)

  • overcome mutation by retesting crime stain and reference sample using other multiplex
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What was the Prum convention 2005?

How was compatibility a problem between different multiplexes?

A
  • many EU countries signed up enabling the routing exchange of DNA profiles and fingerprints
  • loci used in multiplexes used in different countries can vary between tests
  • so it is necessary to find out which were shared and could therefore be compared in cross-border searches
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the ESS?

A
  • European Standard Set of Loci
  • 7 sets of loci (polymorphic) specified as basic set for comparison
  • at least 6/7 of ESS loci are needed before search can be carried out
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What did the Prum convention say about ESS?

A
  • agreed that 7 loci (polymorphic) from ESS should be in all multiplexes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Considering the 6/7 loci that were required to be in all of the multiplexes, what were issues that were soon to be encounted?

A
  • as size of databases grew and number of searches increased, there were some problems due to small number of loci common between profiles
  • more false positives and adventitious matches that needed further testing (false positives mostly seen where number of loci compared is limited)
  • remove this need for further work by adding more loci to standard test
17
Q

What are the two reasons as to why profiles obtained from crime scenes were often too poor to be searched at all?

A
  • DNA was damaged (breaking down or degraded)
  • presence of chemicals in the sample which inhibited the reaction
18
Q

What were the ENFSI requirements for an improved DNA test?

A
  • include more loci (17 loci)
  • be more robust to inhibition
  • get better results from smaller and more degraded samples
19
Q

How is continuity and back compatibility ensured between the old SGM multiplex and DNA 17?

A
  • original 6 SGM loci included in SGM+ test
  • the SGM+ loci are included in the DNA17 tests
20
Q

What is the interpretational issue due to new tests?

A
  • rather than being a single test like SGM+, several companies have produced their own versions of multiplexes (meet/exceed ESS criteria)
  • order and position of loci are not the same between multiplexes
  • therefore the DNA EPG for the same sample tested using two different multiplexes will not be directly comparable by eye
21
Q

What are the benefits of DNA 17?

A

1 - sensitivity has doubled (500 pg is starting threshold whereas previously required 1000 pg)
2 - SGM+ loci have remained
3 - has less problems with chemicals that inhibit samples (potential inhabitants: soil, microbial, plant and faecal contaminants)
4 - PCR cycle number has been increased from standard number of 28 to between 29 and 31 (makes system more sensitive so able to give better profiles from small and degraded samples)
5 - less adventitious matches (chance)
6 - degraded DNA can be dealt with (more loci added at low and high molecular weight)
7 - international benefits
- requests from police and investigators for undetected DNA profiles to be searched against databases from other countries
- easy to travel between countries means can escape abroad
- to deal with cross-border and inter-country crime

22
Q

When was DNA 17 introduced in Europe, England and Wales, and Scotland?

A
  • Europe: 2012 and 2013
  • England and Wales: July 2014
  • Scotland: 21 loci multiplex
23
Q

Legacy

A
  • DNA17 profiles from undetected crime scenes were added to the national DNA database and will be involved in matching to the legacy DNA profiles already loaded that were produced from earlier DNA test multiplexes
24
Q

Watson and Crick and Rosalind Franklin
- who are they
- what happened

A
  • Watson and Crick benefited from the work of two X-ray crystallographers at Kings College London. They used Rosalind Franklins images without his knowledge

FSCI6370 - DNA (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions