Evaluation of forensic DNA mixture evidence: Protocol for evaluation, interpretation, and statistical calculations using the combined probability of inclusion

Frederick R. Bieber, John S. Buckleton, Bruce Budowle, John M. Butler, Michael D. Coble

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Background: The evaluation and interpretation of forensic DNA mixture evidence faces greater interpretational challenges due to increasingly complex mixture evidence. Such challenges include: casework involving low quantity or degraded evidence leading to allele and locus dropout; allele sharing of contributors leading to allele stacking; and differentiation of PCR stutter artifacts from true alleles. There is variation in statistical approaches used to evaluate the strength of the evidence when inclusion of a specific known individual(s) is determined, and the approaches used must be supportable. There are concerns that methods utilized for interpretation of complex forensic DNA mixtures may not be implemented properly in some casework. Similar questions are being raised in a number of U.S. jurisdictions, leading to some confusion about mixture interpretation for current and previous casework. Results: Key elements necessary for the interpretation and statistical evaluation of forensic DNA mixtures are described. Given the most common method for statistical evaluation of DNA mixtures in many parts of the world, including the USA, is the Combined Probability of Inclusion/Exclusion (CPI/CPE). Exposition and elucidation of this method and a protocol for use is the focus of this article. Formulae and other supporting materials are provided. Conclusions: Guidance and details of a DNA mixture interpretation protocol is provided for application of the CPI/CPE method in the analysis of more complex forensic DNA mixtures. This description, in turn, should help reduce the variability of interpretation with application of this methodology and thereby improve the quality of DNA mixture interpretation throughout the forensic community.

Original languageEnglish
Article number125
JournalBMC Genetics
Volume17
Issue number1
DOIs
StatePublished - 31 Aug 2016

Fingerprint

DNA
Alleles
Complex Mixtures
Artifacts
Polymerase Chain Reaction
cyclopropapyrroloindole

Keywords

  • Allele drop-out
  • CPI
  • Combined probability of inclusion
  • Forensic DNA mixtures
  • Stochastic threshold

Cite this

@article{638d75abef1b44308d9d8cb826a7913f,
title = "Evaluation of forensic DNA mixture evidence: Protocol for evaluation, interpretation, and statistical calculations using the combined probability of inclusion",
abstract = "Background: The evaluation and interpretation of forensic DNA mixture evidence faces greater interpretational challenges due to increasingly complex mixture evidence. Such challenges include: casework involving low quantity or degraded evidence leading to allele and locus dropout; allele sharing of contributors leading to allele stacking; and differentiation of PCR stutter artifacts from true alleles. There is variation in statistical approaches used to evaluate the strength of the evidence when inclusion of a specific known individual(s) is determined, and the approaches used must be supportable. There are concerns that methods utilized for interpretation of complex forensic DNA mixtures may not be implemented properly in some casework. Similar questions are being raised in a number of U.S. jurisdictions, leading to some confusion about mixture interpretation for current and previous casework. Results: Key elements necessary for the interpretation and statistical evaluation of forensic DNA mixtures are described. Given the most common method for statistical evaluation of DNA mixtures in many parts of the world, including the USA, is the Combined Probability of Inclusion/Exclusion (CPI/CPE). Exposition and elucidation of this method and a protocol for use is the focus of this article. Formulae and other supporting materials are provided. Conclusions: Guidance and details of a DNA mixture interpretation protocol is provided for application of the CPI/CPE method in the analysis of more complex forensic DNA mixtures. This description, in turn, should help reduce the variability of interpretation with application of this methodology and thereby improve the quality of DNA mixture interpretation throughout the forensic community.",
keywords = "Allele drop-out, CPI, Combined probability of inclusion, Forensic DNA mixtures, Stochastic threshold",
author = "Bieber, {Frederick R.} and Buckleton, {John S.} and Bruce Budowle and Butler, {John M.} and Coble, {Michael D.}",
year = "2016",
month = "8",
day = "31",
doi = "10.1186/s12863-016-0429-7",
language = "English",
volume = "17",
journal = "BMC Genetics",
issn = "1471-2156",
publisher = "BioMed Central Ltd.",
number = "1",

}

Evaluation of forensic DNA mixture evidence : Protocol for evaluation, interpretation, and statistical calculations using the combined probability of inclusion. / Bieber, Frederick R.; Buckleton, John S.; Budowle, Bruce; Butler, John M.; Coble, Michael D.

In: BMC Genetics, Vol. 17, No. 1, 125, 31.08.2016.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Evaluation of forensic DNA mixture evidence

T2 - Protocol for evaluation, interpretation, and statistical calculations using the combined probability of inclusion

AU - Bieber, Frederick R.

AU - Buckleton, John S.

AU - Budowle, Bruce

AU - Butler, John M.

AU - Coble, Michael D.

PY - 2016/8/31

Y1 - 2016/8/31

N2 - Background: The evaluation and interpretation of forensic DNA mixture evidence faces greater interpretational challenges due to increasingly complex mixture evidence. Such challenges include: casework involving low quantity or degraded evidence leading to allele and locus dropout; allele sharing of contributors leading to allele stacking; and differentiation of PCR stutter artifacts from true alleles. There is variation in statistical approaches used to evaluate the strength of the evidence when inclusion of a specific known individual(s) is determined, and the approaches used must be supportable. There are concerns that methods utilized for interpretation of complex forensic DNA mixtures may not be implemented properly in some casework. Similar questions are being raised in a number of U.S. jurisdictions, leading to some confusion about mixture interpretation for current and previous casework. Results: Key elements necessary for the interpretation and statistical evaluation of forensic DNA mixtures are described. Given the most common method for statistical evaluation of DNA mixtures in many parts of the world, including the USA, is the Combined Probability of Inclusion/Exclusion (CPI/CPE). Exposition and elucidation of this method and a protocol for use is the focus of this article. Formulae and other supporting materials are provided. Conclusions: Guidance and details of a DNA mixture interpretation protocol is provided for application of the CPI/CPE method in the analysis of more complex forensic DNA mixtures. This description, in turn, should help reduce the variability of interpretation with application of this methodology and thereby improve the quality of DNA mixture interpretation throughout the forensic community.

AB - Background: The evaluation and interpretation of forensic DNA mixture evidence faces greater interpretational challenges due to increasingly complex mixture evidence. Such challenges include: casework involving low quantity or degraded evidence leading to allele and locus dropout; allele sharing of contributors leading to allele stacking; and differentiation of PCR stutter artifacts from true alleles. There is variation in statistical approaches used to evaluate the strength of the evidence when inclusion of a specific known individual(s) is determined, and the approaches used must be supportable. There are concerns that methods utilized for interpretation of complex forensic DNA mixtures may not be implemented properly in some casework. Similar questions are being raised in a number of U.S. jurisdictions, leading to some confusion about mixture interpretation for current and previous casework. Results: Key elements necessary for the interpretation and statistical evaluation of forensic DNA mixtures are described. Given the most common method for statistical evaluation of DNA mixtures in many parts of the world, including the USA, is the Combined Probability of Inclusion/Exclusion (CPI/CPE). Exposition and elucidation of this method and a protocol for use is the focus of this article. Formulae and other supporting materials are provided. Conclusions: Guidance and details of a DNA mixture interpretation protocol is provided for application of the CPI/CPE method in the analysis of more complex forensic DNA mixtures. This description, in turn, should help reduce the variability of interpretation with application of this methodology and thereby improve the quality of DNA mixture interpretation throughout the forensic community.

KW - Allele drop-out

KW - CPI

KW - Combined probability of inclusion

KW - Forensic DNA mixtures

KW - Stochastic threshold

UR - http://www.scopus.com/inward/record.url?scp=84984698632&partnerID=8YFLogxK

U2 - 10.1186/s12863-016-0429-7

DO - 10.1186/s12863-016-0429-7

M3 - Article

C2 - 27580588

AN - SCOPUS:84984698632

VL - 17

JO - BMC Genetics

JF - BMC Genetics

SN - 1471-2156

IS - 1

M1 - 125

ER -