Benefits of New Multiplexes Flashcards

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1
Q

What is a multiplex?

A

Combinations of loci

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2
Q

What is SGM?

A
  • Second Generation Multiplex
  • comprised of six loci plus a genetic identifier
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3
Q

What is SGM+?

A
  • number of loci increased to 10
  • included all the loci from SGM so that it was back-compatible with previous SGM multiplex
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4
Q

What is the order of all the multiplexes in earliest to latest?

A
  1. RFLP
  2. MLP
  3. SLP
  4. STR-Quad
  5. SGM
  6. SGM+
  7. DNA17
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5
Q

What are the three types of DNA match?

A
  1. between a reference sample and undetected crimes (person to crime)
  2. crime to crime
  3. person to person
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6
Q

The multiplex, used the formation of the DNA database, in 1995 was referred to as?

A

SGM

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7
Q

Why is DNA 17 needed?

A
  • adventitious matches
  • can analyse degraded DNA
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8
Q

Prior to DNA17 we all used SGM so what does this mean for samples?

A

if a crime stain is profiled using one multiplex, and a reference sample uses a different one they may not quite match for several reasons

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9
Q

What is near match reporting?

A

It is used to identify individuals who may not have an exact match to the DNA profile from the crime scene evidence but share significant similarities

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10
Q

What are reasons for non-concordance?

A
  • data entry error
  • two profiles are very similar
  • mutation
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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

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12
Q

How does mutation cause non-concordance?

A
  • crime scene sample might be profiled using one multiplex while the reference sample is profiled with a different multiplex
  • to combat this we can retest the crime stain and reference sample using the same multiplex
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13
Q

What is the Prum Convention 2005?

A

enables the routine exchange of data of DNA profiles and fingerprints

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14
Q

How does compatibility work with the Prum Convention 2005?

A
  • there are many multiplexes that different countries use
  • the loci used can vary between these tests
  • it is necessary to find out which loci were shared and therefore they can be compared in cross-border searches
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15
Q

What is the ESS?

A

European Standard Set
* sets of seven loci were specified as the basic set for comparision
* these seven loci are included in all multiplexes
* at least 6/7 of the ESS loci are needed before a search can be carried out

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16
Q

What are the two reasons that DNA can become damaged?

A
  • breaking down or degraded
  • presence of chemicals in the sample which inhibited the DNA reaction
17
Q

What were the ENFSI requirements for an imrpoved DNA test?

A
  • include more loci
  • be more robust to inhibition
  • get better results from smaller and more degraded samples
18
Q

How is continuity and back compatibility ensured between the old SGM multiplex and DNA17?

A
  • the original six SGM loci were included in the SGM+ test
  • the SGM+ loci are included in the DNA 17 tests
19
Q

What is the interpretational issue due to new tests?

A
  • rather than having a single test like SGM+, several companies have produced their own versions of multiplexes
  • these meet or exceed the ESS criteria
  • the order and position of the loci are not the same between the multiplexes
20
Q

What is benefical about the number of PCR cycles being increased?

A
  • more sensitive
  • able to give better profiles from small and degraded samples
21
Q

What are the benefits of the new multiplexes?

A
  • more sensitive
  • can analyse more degraded smaller samples
  • fewer problems with the chemicals that inhibit samples
  • increased cycle number of PCR
22
Q

The presence of chemicals in the DNA crime sample can influence the quality of the resulting DNA profile. In this instance, the sample is said to be?

A

inhibited

23
Q

The current DNA multiplex requires how many cells to commence the standard test?

A

80