Research Article| Volume 3, ISSUE 2, P112-118, March 2009

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Validation of software for calculating the likelihood ratio for parentage and kinship

Published:December 25, 2008DOI:


      Although the likelihood ratio is a well-known statistical technique, commercial off-the-shelf (COTS) software products for its calculation are not sufficiently validated to suit general requirements for the competence of testing and calibration laboratories (EN/ISO/IEC 17025:2005 norm) per se. The software in question can be considered critical as it directly weighs the forensic evidence allowing judges to decide on guilt or innocence or to identify person or kin (i.e.: in mass fatalities). For these reasons, accredited laboratories shall validate likelihood ratio software in accordance with the above norm.
      To validate software for calculating the likelihood ratio in parentage/kinship scenarios I assessed available vendors, chose two programs (Paternity Index and familias) for testing, and finally validated them using tests derived from elaboration of the available guidelines for the field of forensics, biomedicine, and software engineering. MS Excel calculation using known likelihood ratio formulas or peer-reviewed results of difficult paternity cases were used as a reference.
      Using seven testing cases, it was found that both programs satisfied the requirements for basic paternity cases. However, only a combination of two software programs fulfills the criteria needed for our purpose in the whole spectrum of functions under validation with the exceptions of providing algebraic formulas in cases of mutation and/or silent allele.


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        • Brenner C.H.
        How to Solve Any Kinship Problem by Hand [Online].
        2004 (pp. 1–4)
        • Scientific Working Group on DNA Analysis Methods (SWGDAM)
        Revised Validation Guidelines.
        2003 (pp. 1–6)
        • Advisory Board D.N.A.
        Quality assurance standards for forensic DNA testing laboratories. July 1998.
        Forensic Sci. Commun. 2000; 2: 1-15
        • Barker R.
        • Wichmann B.
        Guidance for accredited laboratories on the use of computers.
        Accredit. Qual. Assur. 2000; 5: 287-288
        • Crumpler S.
        • Cheng J.
        • Tillman D.-B.
        • Benesch B.
        • Sawyer D.
        • Murray J.
        • Press H.
        • Snipes C.
        • Godziemski A.
        • Bergeson D.
        • Loreng J.
        General Principles Of Software Validation; Final Guidance for Industry and FDA Staff, version 2.0.
        2002 (pp. 1–47)
        • Gjertson D.W.
        • Brenner C.H.
        • Baur M.P.
        • Carracedo A.
        • Guidet F.
        • Luque J.A.
        • Lessig R.
        • Mayr W.R.
        • Pascali V.L.
        • Prinz M.
        • Schneider P.M.
        • Morling N.
        ISFG: recommendations on biostatistics in paternity testing.
        Forensic Sci. Int. Genet. 2007; 1: 223-231
        • Green J.M.
        A practical guide to analytical method validation.
        Anal. Chem. 1996; 68: A305-A309
        • Huber L.
        Qualification and validation of software and computer systems in laboratories—Part 2: qualification of vendors.
        Accredit. Qual. Assur. 1998; 3: 2-5
        • Huber L.
        Qualification and validation of software and computer systems in laboratories—Part 3: installation and operational qualification.
        Accredit. Qual. Assur. 1998; 3: 140-144
        • Huber L.
        Qualification and validation of software and computer systems in laboratories—Part 4: evaluation and validation of existing systems.
        Accredit. Qual. Assur. 1998; 3: 317-321
        • Hattacharya S.
        • Kanjilal A.
        Code based analysis for object-oriented systems.
        J. Comput. Sci. Technol. 2006; 21: 965-972
        • Marks D.M.
        Testing Very Big Systems.
        McGraw-Hill, The United States of America1992
        • Brenner C.H.
        A note on paternity computation in cases lacking a mother.
        Transfusion. 1993; 33: 51-54
        • Ayres K.L.
        Relatedness testing in subdivided populations.
        Forensic Sci. Int. 2000; 114: 107-115
        • Huber L.
        • Wiederoder H.
        Qualification and validation of software and computer systems in laboratories—Part 1: validation during development.
        Accredit. Qual. Assur. 1997; 2: 360-366
        • Brenner C.
        • Staub R.W.
        Can DNA solve this? Poster presented at the 14th International Symposium on Human Identification, Phoenix, AZ, September 30–October 22003: 1-2
        • Blouin M.S.
        DNA-based methods for pedigree reconstruction and kinship analysis in natural populations.
        Trends Ecol. Evol. 2003; 18: 503-511
        • Kalinowski S.T.
        • Taper M.L.
        • Marshall T.C.
        Revising how the computer program CERVUS accommodates genotyping error increases success in paternity assignment.
        Mol. Ecol. 2007; 16: 1099-1106
        • Cole J.B.
        PyPedal: a computer program for pedigree analysis.
        Comput. Electron. Agric. 2007; 57: 107-113
        • Gerber S.
        • Chabrier P.
        • Kremer A.
        FAMOZ: a software for parentage analysis using dominant, codominant and uniparentally inherited markers.
        Mol. Ecol. Notes. 2003; 3: 479-481
        • Sefc K.M.
        • Lopes M.S.
        • Lefort F.
        • Botta R.
        • Roubelakis-Angelakis K.A.
        • Ibanez J.
        • Pejic I.
        • Wagner H.W.
        • Glossl J.
        • Steinkellner H.
        Microsatellite variability in grapevine cultivars from different European regions and evaluation of assignment testing to assess the geographic origin of cultivars.
        Theor. Appl. Genet. 2000; 100: 498-505
        • Konovalov D.A.
        • Manning C.
        • Henshaw M.T.
        KINGROUP: a program for pedigree relationship reconstruction and kin group assignments using genetic markers.
        Mol. Ecol. Notes. 2004; 4: 779-782
        • Ritland K.
        Extensions of models for the estimation of mating systems using on independent loci.
        Heredity. 2002; 88: 221-228
        • Rocheta M.
        • Dionisio F.M.
        • Fonseca L.
        • Pires A.M.
        Paternity analysis in Excel.
        Comput. Methods Programs Biomed. 2007; 88: 234-238
        • Cowell R.G.
        FINEX: a Probabilistic expert system for forensic identification.
        Forensic Sci. Int. 2003; 134: 196-206
        • Egeland T.
        • Mostad P.F.
        • Mevag B.
        • Stenersen M.
        Beyond traditional paternity and identification cases. Selecting the most probable pedigree.
        Forensic Sci. Int. 2000; 110: 47-59
        • Dajda T.
        • Jung M.
        LR-calculation of any kinship situation using a new graphical interface: generate two or more hypotheses, draw the family trees and assign the DNA-profiles to person symbols.
        ICS. 2006; 1288: 474-476
        • Phillips C.
        • Fondevila M.
        • García-Magarinos M.
        • Rodriguez A.
        • Salas A.
        • Carracedo A.
        • Lareu M.V.
        Resolving relationship tests that show ambiguous STR results using autosomal SNPs as supplementary markers.
        Forensic Sci. Int. Genet. 2008; 2: 198-204
      1. A.B. Hepler, Improving forensic identification using Bayesian networks and relatedness estimation: allowing for population substructure. Ph.D. Thesis. North Carolina State University, Department of Statistics, Raleigh, 2005.

        • Brenner C.
        • Morris J.W.
        Paternity index calculations in single locus hypervariable DNA probes: validation and other studies.
        in: Proceedings for the International Symposium on Human Identification 1989. Promega Corp, 1990: 21-53
        • Berent J.
        [DNAStat, version 1.2—a software package for processing genetic profile databases and biostatistical calculations].
        Arch. Med. Sadowej Kryminol. 2007; 57: 322-325
        • Brenner C.H.
        Symbolic kinship program [published erratum appears in Genetics 147 (September (1)) (1997) following 398].
        Genetics. 1997; 145: 535-542
        • Fung W.K.
        User-friendly programs for easy calculations in paternity testing and kinship determinations.
        Forensic Sci. Int. 2003; 136: 22-34
        • Riancho J.A.
        • Zarrabeitia M.T.
        A Windows-based software for common paternity and sibling analyses.
        Forensic Sci. Int. 2003; 135: 232-234
        • Krawczak M.
        • Bockel B.
        A genetic-factor model for the statistical-analysis of multilocus DNA fingerprints.
        Electrophoresis. 1992; 13: 10-17
      2. P. Linhart, Pravdepodobnost rodokmene a jeji pouziti v soudnim lekarstvi [Pedigree probability and its use in forensic medicine]. Bc. Thesis. Silesian University Opava, Faculty of Philosophy and Science, Institute of Informatics, 2001.

      3. C. Brenner, Mutations in Paternity [Online], 2000,

        • Dawid A.P.
        • Mortera J.
        • Pascali V.L.
        Non-fatherhood or mutation? A probabilistic approach to parental exclusion in paternity testing.
        Forensic Sci. Int. 2001; 124: 55-61
        • Dawid A.P.
        • Mortera J.
        • Pascali V.L.
        • van Boxel D.
        Probabilistic expert systems for forensic inference from genetic markers.
        Scand. J. Stat. 2002; 29: 577-595