Proficiency Testing

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In 1992, the Spanish and Portuguese Speaking Group of the International Society for Forensic Genetics (GHEP-ISFG, formerly GEP-ISFG) began organizing an annual collaborative exercise for DNA polymorphism research, in collaboration with the Madrid Department of the National Institute of Toxicology and Forensic Sciences (INTCFM, Spain), with the aim of advancing in the standardization of methods and providing a first meeting point to discuss the analysis strategies and the different methodologies used by the different laboratories.

These exercises have given rise to work meetings, a discussion forum among the participants where the difficulties involved in the analysis of DNA polymorphisms and the legal and practical need for the analyses to be carried out with the necessary guarantee are exposed. With this perspective, in 1995, the exercise began to function as a true Quality Control, in which the laboratories that obtained poor results in any of the markers used, promised not to use it in forensic cases until the situations that had caused the error were resolved and submitted to a new control.

Currently, the Intercomparison Exercise "STUDY OF DNA POLYMORPHISMS IN BLOODSTAINS AND OTHER BIOLOGICAL SAMPLES" is divided into two levels: Basic and Advanced, which, in turn, are divided into 2 modules: kinship and forensic.

Since 2014, the Basic level has been accredited under the ISO/IEC 17043:2010 Standard. It is coordinated by the INTCFM and organized by the GHEP-ISFG, annually.

The exercise consists of sending various samples of blood and/or other biological fluid and hair for analysis by the participating laboratories, simulating a real case. The exercise includes not only the analytical part but also an applied statistics section, with the purpose of serving the laboratories, not only for checking the results, but also to highlight the discrepancies between some laboratories making it a starting point for a unification and normalization of techniques and criteria.

Until 2022, thirty editions of the Exercise have been held and the number of participating laboratories has been increasing, going from 10 laboratories in the first exercise to about 150 in recent years.

The participating laboratories are located mainly in Spain and Portugal and in different Latin American countries. Most of the participants are public laboratories, although the number of registered private laboratories is increasing.

The studies are performed by PCR analysis of different genetic markers: autosomal, Y chromosome and X chromosome STRs, and mitochondrial DNA. The exercise includes a basic kinship study and a forensic one. In addition, the GHEP-ISFG includes two advanced theoretical challenges (ATC), kinship and forensic, developed by one or more internationally recognized experts, in a way that allows scientific discussion among professionals and contributes to the development of interpretation criteria and the advanced training of participants.

The results obtained, despite the increase in participants, are satisfactory and are published annually after the corresponding Meeting is held so that people who are interested in it can consult them.

The effort made in carrying out this exercise is offset by the good acceptance it has had, as well as by the good results that are being obtained, which helps enormously, together with other activities launched by the Group, to increase and unify the quality of analyses in Forensic Genetics laboratories in Spain, Portugal and Latin America.

Any interested laboratory can participate in the Exercise. Each laboratory is assigned a code to guarantee the anonymity of the results.

The exercise is annual, opening the registration period in the last quarter of each year and sending the samples in February/March of the following year.

References

Gómez J. Carracedo A for the Spanish and Portuguese Working Group of the ISFH. A review of the collaborative exercises of the Spanish and Portuguese ISFH Working Group. Advances in Forensic Haemogenetics 6: 695-698 (1996).

Gómez J. et al. A review of the collaborative exercise on DNA typing of the Spanish and Portuguese ISFH working group. Int J Leg Med 110:273-277 (1997).

Gómez J. et al. The 1998-1999 collaborative exercises and proficiency testing program on DNA typing of the Spanish and Portuguese Working Group of the International Society for Forensic Genetics (GEP-ISFG). Forensic Sci Int 114(1): 21-30 (2000).

Alonso A. et al. Results of the 1999-2000 collaborative exercise and proficiency testing program on mitochondrial DNA of the GEP-ISFG: an interlaboratory study of the observed variability in the heteroplasmy level of hair from the same donor.Forensic Sci Int 125: 1-7 (2002).

Prieto L. et al. The 2000-2001 GEP-ISFG collaborative exercise on mtDNA: assessing the cause of unsuccessful mtDNA PCR amplification of hair shaft samples. Forensic Sci Int 134: 46-53 (2003).

Gómez J. et al. The proficiency testing program on DNA typing of the Spanish and Portuguese Working Group of the International Society for Forensic Genetics (GEP-ISFG). En Progress in Forensic Genetics 9: 837-840 (2003).

Gómez J. et al. GEP proficiency testing programme in forensic genetics: Ten years of experience. Progress in Forensic Genetics 10: 124-126 (2004).

Salas A. et al. Mitochondrial DNA error prophylaxis: assessing the causes of errors in the GEP's 02-03 proficiency testing trial. Forensic Sci Int 148: 191-198 (2005).

García-Hirschfeld J. et al. 2004-2005 GEP proficiency testing programs: special emphasis on the interlaboratory analysis of mixed stains. Progress in Forensic Genetics 11: 855-857 (2006).

Crespillo M. et al. Results of the 2003-2004 GEP-ISFG collaborative study on mitochondrial DNA: focus on the mtDNA profile of a mixed semen-saliva stain. Forensic Science International 160: 157-167 (2006).

Prieto L. et al. 2006 GEP-ISFG collaborative exercise on mtDNA: reflections about interpretation, artefacts and DNA mixtures. Forensic Science International: Genetics 2: 126-133 (2008).

García-Hirschfeld J. et al. GEP-ISFG proficiency testing programs: 2007 update. Forensic Science International: Genetics Supplement Series 1 674-676 (2008).

Prieto L et al. GHEP-ISFG proficiency test 2011: Paper challenge on evaluation of mitochondrial DNA results. Forensic Science International: Genetics 7: 10-15 (2013). 

Fernandez K et al. Accreditation of the GHEP-ISFG proficiency test: one step forward to assure and improve quality. Forensic Science International: Genetics Suppl Series 5: e515-e517 (2015).

Toscanini U et al. Analysis of uni- and bi-parental markers in mixture samples:Lessons from the 22nd GHEP-ISFG intercomparisson exercise. Forensic Science International: Genetics 25: 63-72 (2016).