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CATEGORIES:Isaac Newton Institute Seminar Series
SUMMARY:Evaluation of forensic DNA profiles while accounti
ng for one and two repeat less and two repeat more
stutters - Roberto Puch-Solis ()
DTSTART;TZID=Europe/London:20161109T093000
DTEND;TZID=Europe/London:20161109T101500
UID:TALK68890AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/68890
DESCRIPTION:Co-author: Dr Therese Graversen (University
of Copenhagen)
Current forensic D
NA profile technology is very sensitive and can pr
oduce profiles from a minute amount of DNA\, e.g.
from one cell. A profile from a stain recovered
from a crime scene is represented through an elect
ropherogram (epg)\, which consists of peaks locat
ed in positions corresponding to alleles. Peak he
ights are related to the originating amount of DNA
: the more DNA the sample contains\, the taller t
he peaks are.
An epg also tends to contai
n artefactual peaks of different kinds. Some of t
hese artefacts originate during PCR duplication an
d are usually called &lsquo\;stutters&rsquo\;. Th
e most predominant of the stutter appears one STR
less to the corresponding alleles and it is about
10% of the height of the allelic peak\, although
this percentage vary from locus to locus. Given t
he sensitivity of the DNA systems\, other stutter
s also tend to appear in the epg: one located two
STR less and the other one STR more of the alleli
c peak. They tend to be much smaller than their c
orresponding one STR less stutters.
Many
stain profiles from samples taken from a scene of
a crime originate from more than one person where
each of them contributes different amounts of DNA
. The peaks of minor contributors can be about th
e same height of the stutters of a major contribu
tor. A stutter could also combine with an allelic
peak or with other stutters\, making an evaluatio
n more complicated. Caseworkers are also scrutini
sed on their stutters designations in court.
Graversen & Lauritzen (2015) introduced an eff
icient method for calculating likelihood ratios u
sing Bayesian Networks. In this talk\, this method
is extended to consider two STR less and one STR
more stutters\, and the complexities of the exte
nsion is discussed.
Reference
Graversen T. & Lauritzen S. (2015). Computatio
nal aspects of DNA mixture analysis: exact infere
nce using auxiliary variables in a Bayesian networ
k. Statistics & Computing 25\, pp. 527-541. \
;
LOCATION:Seminar Room 1\, Newton Institute
CONTACT:INI IT
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