Statistical model for degraded DNA samples and adjusted probabilities for allelic drop-out

TY - JOUR

T1 - Statistical model for degraded DNA samples and adjusted probabilities for allelic drop-out

AU - Tvedebrink, Torben

AU - Eriksen, Poul Svante

AU - Mogensen, Helle Smidt

AU - Morling, Niels

PY - 2012/1

Y1 - 2012/1

N2 - DNA samples found at a scene of crime or obtained from the debris of a mass disaster accident are often subject to degradation. When using the STR DNA technology, the DNA profile is observed via a so-called electropherogram (EPG), where the alleles are identified as signal peaks above a certain level or above a signal to noise threshold. Degradation implies that these peak intensities decrease in strength for longer short tandem repeat (STR) sequences. Consequently, long STR loci may fail to produce peak heights above the limit of detection resulting in allelic or locus drop-outs. In this paper, we present a method for measuring the degree of degradation of a sample and demonstrate how to incorporate this in estimating the probability of allelic drop-out. This is done by extending an existing method derived for non-degraded samples. The performance of the methodology is evaluated using data from degraded DNA, where cases with varying amounts of DNA and levels of degradation are investigated.

AB - DNA samples found at a scene of crime or obtained from the debris of a mass disaster accident are often subject to degradation. When using the STR DNA technology, the DNA profile is observed via a so-called electropherogram (EPG), where the alleles are identified as signal peaks above a certain level or above a signal to noise threshold. Degradation implies that these peak intensities decrease in strength for longer short tandem repeat (STR) sequences. Consequently, long STR loci may fail to produce peak heights above the limit of detection resulting in allelic or locus drop-outs. In this paper, we present a method for measuring the degree of degradation of a sample and demonstrate how to incorporate this in estimating the probability of allelic drop-out. This is done by extending an existing method derived for non-degraded samples. The performance of the methodology is evaluated using data from degraded DNA, where cases with varying amounts of DNA and levels of degradation are investigated.

KW - Allelic dropout

U2 - 10.1016/j.fsigen.2011.03.001

DO - 10.1016/j.fsigen.2011.03.001

M3 - Journal article

SN - 1872-4973

VL - 6

SP - 97

EP - 101

JO - Forensic Science International: Genetics

JF - Forensic Science International: Genetics

ER -